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Map of moderate, high and very high threat volcanoes in CA

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Hurricane Hilary will introduce tropical storm-force winds, urban flooding and the risk of isolated tornadoes to large swaths of California on Sunday.

The unusual path of Hurricane Hilary will bring the storm into Southern California on Sunday afternoon. The National Hurricane Center predicts that the system will make landfall in Baja California as a hurricane before weakening to a tropical storm as it enters the U.S. Weather conditions are likely to be most intense Sunday. Hazards include strong winds, heavy downpours, flash flooding, high surf and thunderstorms.

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A tropical storm warning, the first of its kind for California, has been issued for Sunday across Los Angeles, Orange, San Diego, San Bernardino and Riverside counties. Winds are expected to pick up Sunday afternoon, with gusts up to 50 mph possible along the immediate coast between L.A. and the U.S.-Mexico border.

Weather models favor an eastern track for Hilary, meaning that the strongest winds and heaviest rainfall are likely to occur in the outer suburbs of L.A. and San Diego and desert communities such as Palm Springs. Winds on Sunday could gust to 70 mph in communities along the San Bernardino and San Jacinto mountains - up to 80 mph in the San Gabriels to the north of L.A. Weaker winds could spill into Northern California, with gusts to 35 mph possible across the Bay Area on Sunday afternoon into Monday morning.

Strong winds are likely to raise rough seas along the Southern California coast. The National Weather Service issued a high surf advisory for Orange County's shoreline from 8 a.m. Sunday to 2 a.m. Tuesday, where strong rip currents and 4- to 7-foot waves are expected. Occasional sets could even surpass 10 feet in Newport Beach.

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Impacts from Hurricane Hilary began Saturday across the Mojave Desert. A predecessor rain event, an offshoot of moisture more than 1,000 miles from the hurricane's center, brought thunderstorms and heavy rainfall along the California-Nevada border. Thunderstorms and downpours are expected to become more widespread throughout the day Saturday as Hilary approaches.

There is a chance of thunderstorms spilling into the Bay Area between 10 p.m. Saturday and 2 a.m. Sunday, most likely in the East Bay in places like the Oakland Hills. Saturday's storms are expected to extend into the Central Valley and could even clip far southeastern Santa Clara County. The Storm Prediction Center is forecasting a marginal risk of severe thunderstorms for Fresno, Tulare and Merced during the afternoon and evening. Localized severe wind gusts are the primary threat.

On Sunday, the Weather Prediction Center forecasts a high chance of excessive rainfall from Hilary's rains in desert communities such as Palm Springs and along the U.S.-Mexico border.

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Hilary was weakening as it approached California, but it effects were still expected to be "catastrophic" in parts of the state, specifically in the deserts of California and southeastern parts of the state, according to UCLA climate scientist Daniel Swain said Saturday. While rain wasn't expected to reach fires in northwest California, Hilary could bring smoky and humid conditions to the Bay Area and Northern California in the next few days, he said.

Flood watches are in effect until Monday evening for the L.A. suburbs in Riverside and San Bernardino counties, the Mojave Desert and the San Diego County mountains. Downpours Sunday could bring as much as 5 inches of rain to parts of the desert. The flash flood watch will also include the city of San Diego and all of Orange County.

Thunderstorms are also expected Sunday night and into Monday. The Storm Prediction Center is forecasting a low risk of isolated tornadoes across Southern California, in addition to a marginal risk of thunderstorms, on Sunday and Monday. Brief tornadoes could cause localized damage.

Some of Hilary's extreme weather could make it to the Sierra Nevada on Sunday and Monday, where excessive rainfall could raise the risk of flash flooding around Mammoth Lakes, Yosemite and parts of Tahoe. Up to 2 inches of rain could fall in the northern Sierra, while the heaviest downpours raise as much as 4 inches of rain in the southern Sierra and Kern County mountains.

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Bay Area and Sacramento Valley residents are likely to be spared from Hilary's heaviest rainfall and strongest winds. Weather models favor a track that keeps Hilary away from the Northern California coast. Winds along Highway 1 from San Francisco to San Luis Obispo are likely to reach gusts to 40 mph on Sunday, but they'll subside quickly Sunday evening. Rainfall totals are expected to range from a few hundredths of an inch in San Francisco to as much as a quarter of an inch in the inland valleys of the Bay Area - still above average for this time of year.

Sunnier skies and drier weather slowly return to California by Monday night and into Tuesday morning as Hilary's remnants drift away. Be sure to subscribe to the Weather Wonks for updates to the weather forecast.

Saturday breakdown

San Francisco: Expect foggy conditions on the west side and partly cloudy skies east of Sutro Tower through noon. The air will generally be warm and muggy, with daytime temperatures reaching the upper 60s in the Presidio and west side and lower 70s downtown and in the Castro and Mission.

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Fog and drizzle will eventually return in the evening, especially around Twin Peaks and the immediate shoreline. Look for nighttime lows in the lower 60s.

East Bay: Puffy cumulus clouds and daytime temperatures in the upper 80s to lower 90s are on tap for the Tri-Valley. There is a slight chance of a stray thunderstorm or two forming over the Diablo Range in the afternoon. Thunderhead clouds could make for a dramatic sunset in Walnut Creek, Pleasanton and Dublin.

The cool bay breeze will keep partly cloudy skies in place and temperatures closer to the mid-70s in Oakland, Alameda and Fremont. Expect nighttime temperatures to return to the lower 60s by the water and mid-60s inland.

North Bay: Residents in Santa Rosa, Petaluma and Napa can expect partly cloudy skies and daytime temperatures in the lower 80s. The warmest and muggiest air will set up shop in Solano County. Look for highs in the lower 90s this afternoon in Fairfield and Vacaville.

Cooler and foggier air will limit daytime highs to the lower 70s in Sausalito and Tiburon, while warmer air inland allows temperatures to reach the mid-80s along the Highway 101 corridor - Novato, San Rafael and Mill Valley.

Fog on the bay shore could briefly cause drizzles tonight as temperatures fall to the lower 60s by the water and mid-60s inland.

Pacific Coast and Peninsula: Morning and evening drizzles are on tap for most of the Highway 1 corridor between Daly City and Half Moon Bay. Residents along the coast will get a few breaks in the fog in the afternoon, but the cool breeze off the Pacific Ocean will keep temperatures in the lower 70s.

Cool air from the Pacific Ocean will stave off the inland heat in Millbrae, Colma and South San Francisco. Look for partly cloudy skies and daytime highs in the upper 70s along the San Bruno Gap. Expect sunnier skies and highs in the lower 80s for residents south of San Mateo and along the I-280 and Highway 101 corridors.

Overnight fog could raise the odds of drizzle on the immediate coast while temperatures fall to the lower 60s.

South Bay and Santa Cruz: The ebb and flow of marine clouds continues. Residents along Monterey Bay can expect partly cloudy skies in the afternoon as daytime temperatures reach the mid-70s.

Residents in the Santa Cruz Mountains can expect a warm and muggy afternoon, with temperatures climbing to the lower 80s. Hot air and a slight chance of thunderstorms between 2 and 6 p.m. are also on tap in the Santa Clara Valley, where daytime highs will reach the mid- to upper 80s.

The air will stay warm and muggy overnight in the inland valleys, where nighttime temperatures might fall only to the upper 60s. Cooler air closer to the coast will bring temperatures down to 60 for La Selva, Capitola and Aptos.

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Hurricane Hilary will impact large swaths of California for days. Here's the outlook

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Hurricane Hilary's weather forecast continues to rapidly evolve. Here's an update on what Californians can expect over the next few days

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Home CGS California Tsunami Maps and Data

Tsunami Hazard Area Maps for California cover much of the state's populated coastal areas and will one day cover the entire California coast. Explore your area of interest in the map-zoom in, pan, and click (or tap) a coastal location to invoke a pop-up window that provides additional information and links. NOTE: there may be many results in the pop-up, depending on where you click. We recommend you zoom in to a specific area of interest before using the pop-up feature.

You may also Open the map in a new window

Other Tsunami Map Products

MyHazards by Cal OES provides a website where you can find out if you live within an area at risk to hazards from tsunamis, earthquakes, flooding, and fire.

Spatial Data for GIS users

For GIS users, we offer the following links to our tsunami map shapefiles and ArcGIS REST services. These are statewide data sets; however, the 2021 data cover only the counties updated in 2021. Similarly, the 2009 data cover only the counties not updated in 2021. Therefore, to get the most complete tsunami data coverage for California's coast, you must utilize the 2021 and 2009 data together.

About the Maps

California Tsunami Hazard Area Maps and data are prepared to assist cities and counties in identifying their tsunami hazard for tsunami response planning. The maps and data are compiled with the best currently available scientific information and represent areas that could be exposed to tsunami hazards during a tsunami event. They are primarily based on inundation limits corresponding to a 975-year average return period tsunami event model. These limits have been extended to reflect potential local tsunami sources not considered in probabilistic analysis and are also modified to reflect the practical need to define limits that coincide with geographic features or city streets. The following documents explain the methodology for determining inundation and evacuation areas.

Disclaimer

California Official Tsunami Hazard Area Maps are prepared to assist cities and counties in identifying their tsunami hazard. They are intended for local jurisdictional, coastal evacuation planning uses only. They are not legal documents and do not meet disclosure requirements for real estate transactions nor for any other regulatory purpose. The California Governor's Office of Emergency Services (Cal OES), the University of Southern California (USC), AECOM Technical Services, and the California Geological Survey (CGS) make no representation or warranties regarding the accuracy of the maps nor the data from which the maps were derived. The State of California shall not be liable under any circumstances for any direct, indirect, special, incidental or consequential damages with respect to any claim by any user or any third party on account of or arising from the use of these maps.

How to cite California Tsunami Maps

When citing the maps in your research, please use the following format (entering the specific map name, county name, and date on the map where indicated):

For 2021 maps:

State of California, 2021, Tsunami Hazard Area Map, County name County; produced by the California Geological Survey, the California Governor's Office of Emergency Services, and AECOM; dated date on the map, mapped at multiple scales.

For 2009 maps:

State of California, 2009, Tsunami Inundation Map for Emergency Planning, Map name Quadrangle, County name County; produced by California Emergency Management Agency, California Geological Survey, and University of Southern California - Tsunami Research Center; dated date on the map, mapped at 1:24,000 scale.

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California Department of Conservation administers a variety of programs vital to California's public safety, environment and economy. The services DOC provides are designed to balance today's needs with tomorrow's obligations by fostering the wise use and conservation of energy, land and mineral resources.

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Scenic hill slopes can be inspiring - or deadly, as we are seeing after the disastrous debris flows that have ravaged the community of Montecito, California in the wake of heavy rains on Tuesday, Jan. 9, 2018. At least 20 people are dead, and four remain missing. More than a hundred buildings have been destroyed or damaged by moving walls of mud and boulders that rumbled down creeks and canyons into houses and roads.

As mountains rise, erosion tears them down. And Southern California's mountains are rising fast, squeezed up by the action of the region's active faults. This produces steep slopes that erode quickly, though much of that erosion happens in infrequent events, such as big rainstorms right after big wildfires.

We know that risks vary across the terrain and that some places in landslide-prone zones are more dangerous than others. In some regions the riskiest areas are well downslope or downstream of slide-prone slopes, in the places where debris runs out and comes to rest. Unfortunately, few people are aware of these risks when developers build in and around landslide-prone mountains.

A predictable disaster

The U.S. Geological Survey estimates that landslides kill 25 to 50 people a year in the United States - more than earthquakes or volcanoes. Yet landslides receive far less attention and research funding than other natural hazards.

Part of the problem is that when a large earthquake strikes, the whole region feels it. But landslides tend to impact localized areas, so they rarely attract widespread attention, except in devastating cases like Montecito. Furthermore, different kinds of landslides present very different hazards. Assessing landslide risks requires an understanding of how erosional processes shape Earth's surface in different regions.

In a general sense, the threat to Montecito was clear. Scientists and planners have known for decades that the mountains of Southern California are shaped by a cycle of fire, rain and debris flows. Back in 1989, when I was a graduate student studying landslides, journalist John McPhee published his acclaimed book "The Control of Nature." In it, McPhee described scenes of devastation resulting from intense rainfall running off of wildfire-charred slopes to roar down canyons around Los Angeles.

The Montecito disaster did not come as a complete surprise. Indeed, the U.S. Geological Survey warned of high potential for disastrous landslides if intense rain fell on mountainsides around Santa Barbara that had been scorched by the Thomas wildfire in December. When that perfect storm landed, it hit bare, baked soil that could not readily absorb water. So the rain ran off, picking up soil, boulders and debris as it surged down canyons and streams. These debris-charged torrents slowed only where steep channels gave way to gentler slopes.

Most of the damage occurred along the run-out pathways of the debris flows - areas where material can flow after it starts sliding downhill. Yet landslide hazard maps generally don't show predicted run-out zones. Instead, they typically show only the locations of the source areas where landslides are likely to start.

Better information for residents

There are reasons why people keep building homes in landslide-prone areas. Some decide it's worth the risk. In Seattle, where I live, steep slide-prone slopes tend to offer the best, and most expensive, views. Conversely, in low-income regions such as Appalachia and many developing countries, the poor often are pushed up onto potentially unstable hillsides. Generally, however, I suspect that many Americans living in landslide country are simply unaware of potential hazards that the lay of the land presents to their homes, neighborhoods and businesses.

Sometimes politics or greed plays a role. After Hurricane Frances hammered North Carolina in 2004, the state legislature approved a program to map landslide hazards. But once the first maps were produced, the program was canceled over concerns that the maps would affect land values and be used to regulate development.

Without this kind of information, residents are physically and financially exposed. "Earth movement," such as landslides, generally is not covered by homeowner's insurance policies. And by the time a landslide comes, developers are long gone, leaving homeowners holding the bag.

And, of course, different types of landslides pose different risks. In the slow-moving Rattlesnake Ridge landslide in central Washington state, a 20-acre parcel of land is sliding downhill about a foot and half per week. Residents have been moved out of the at-risk zone, and engineers and geologists are monitoring the site in real time to evaluate and update hazard assessments.

In contrast, the Oso landslide north of Seattle on March 22, 2014 was so large and fast-moving that even a real-time warning would not have prevented tragedy. This disaster killed 43 people in a couple of minutes when an entire hillside collapsed. In response, Washington state has started posting detailed topographical maps online for use in identifying areas at risk for generating landslides. But hazard maps still don't identify potential downhill run-out zones.

It's time to get serious about landslide zoning, in the way that the federal government maps areas at serious risk of flooding. Landslide hazard maps delineating potential run-out zones should be part of local land use planning. These maps could help guide zoning decisions and better inform homeowners, banks and insurance companies of potential risks. Ultimately, the best way to reduce landslide risk is to avoid building things we value in places where run-out is likely. For when there's no controlling nature, there's only living with her.

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Deadly California mudslides show the need for maps and zoning that better reflect landslide risk

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Scenic hill slopes can be inspiring - or deadly, as we are seeing after the disastrous debris flows that have ravaged the community of Montecito, California in the wake of heavy rains on Tuesday, Jan. 9, 2018. At least 20 people are dead, and four remain missing.

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Montecito Mudslides Anniversary, Reflections Through Images

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As the anniversary of the devastating mudslides in Montecito, Calif., is upon us we want to remember the lives lost and the toll taken on their families and community.

Residents were awoken in the pre-dawn hours of Jan. 9, 2018, to the horrifying sound of mud and boulders plowing down the Santa Barbara hillsides; the sky glowed orange from fires blazing from a ruptured gas main. The burn-scarred Santa Ynez Mountains lining the Southern California town had given way under the short-lived but torrential downpour of an overnight storm. By the time the sun came up, the destruction left behind became apparent. Boulders the size of houses, carried by the strength of rushing mud 15 feet deep, had ravaged homes, reducing many to splintered two-by-fours, or leveled them completely. Many of those that remained intact were filled with several feet of mud and debris. A total of 23 people died, but there were also stories of heroic and selfless actions.

Below is a collection of images and videos released in the days and weeks following the disaster.

Montecito Mudslide US&R Update

(Air Date: Jan. 17, 2018) Mutual aid crews from around California continue to work at this hour to reopen Highway 101 in Santa Barbara, city and county roads and push forward with urban search and rescue missions. It's now been one week since the mudslide devastated this area, taking lives and displacing others. The transition to search and recovery has been made, with a top priority of finding the three persons still missing. Evacuation areas are still not safe for anyone to travel, but the overall recovery mission is ongoing, and local, state and federal resources are fully committed.

INSIDE LOOK: Southern California & Santa Barbara Debris Flow Response

(Air Date: Jan. 11, 2018)

CalOES Inside Look: Montecito Mudflows Recovery Update

(Air Date: Feb. 2, 2018)

Podcast: Amber Anderson, At Home with the Santa Barbara Mudslide

(Air Date: Jan. 23, 2018) We sit down with Amber Anderson, an 18-year veteran firefighter, and 10-year veteran of the Santa Barbara City Fire Department. She's a member of the Santa Barbara County Type-3 Incident Management Team, a fire inspector and investigator and public information officer. In this episode Amber talks about the fire community always learns from previous disasters; this time it's the Thomas Fire and the ensuing flood and mudslide which devastated her county and the community of Montecito.

She also reflects on how Santa Barbara stood-up their incident management team just prior to the floods and just how important that decision was given the damage and deaths that resulted from the floods. And how in the world was she able to keep a smile on her face amid the long hours, demands and stress put on her during her activation and deployment to the disaster in her hometown? She'll answer that question and more in this episode. Oh, and never mind the noise. It's a disaster recovery operation.

Facts and Figures
Situation at that Time:

The County transitioned from Search and Rescue mode to Search and Recovery. Crews continue searching buildings and debris flows for trapped victims.

The unstable environment remains a critical threat to civilians and responders.

Large amounts of mud and debris make access and progress challenging.

Damage inspection is ongoing with six damage assessments teams including building inspectors scheduled to go out in the field.

The shelter at the Santa Barbara City College transitioned as of 1/15/18 to the San Marcos High School - 4750 Hollister Ave., Santa Barbara

Earl Warren Showgrounds animal shelter

Proclamations/Declaration:

On January 2, 2018, FEMA Declared a Major Disaster, (FEMA DR-4353) with an incident period starting on December 4, 2017 for Ventura and Santa Barbara Counties.

The Declaration was granted for Public Assistance and Hazard Mitigation.

On January 10, 2018, the Declaration was expanded to include flooding; mud and debris flows in the designated fire areas; and the USDA Emergency Loan Program for the primary Counties of Ventura and Santa Barbara and contiguous Counties of Kern, Los Angeles and San Luis Obispo.

On January 15, 2018, the Declaration was amended to include Individual Assistance for Los Angeles, San Diego, Santa Barbara, and Ventura Counties.

On January 8, 2018, Santa Barbara County proclaimed a local emergency. The proclamation was ratified on January 9, 2018, accompanied by a formal request for the Governor to proclaim a state of emergency.

On January 7, 2018, the City of Burbank requested a proclamation.

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Montecito Mudslides Anniversary, Reflections Through Images

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on 12th Feb 2021 California Access Doors

Volcanoes are one of the unique parts of the earth. If you're a California resident, you may know a few volcanoes such as Mount Shasta, Lassen Peak, Brushy Butte, Twin Buttes, Pisgah Crater, and Medicine Lake.

While volcanoes are fascinating to learn about, the hazards they pose are a part of life for many Californians. Seismologists have found that there are at least seven active volcanoes around California. They may not physically show signs of activity, but that's typical for volcanoes. They lie dormant for years and suddenly erupt without warning. Fortunately, seismologists and other scientists ensure that they study these volcanoes to prepare Californians when the time comes.

Explore our list of the top 7 active volcanoes in California...

1. Medicine Lake Volcano

You can find the Medicine Lake Volcano in the northeastern part of California, about 30 miles northeast of Mount Shasta, another active volcano. The volcano has an elevation of 7,795 feet, and the lava inside is around 140 cubic miles in volume. It is known as the largest volcano in terms of volume in the Cascade Range. You can also find the Lava Beds National Monument on the northeast side of the volcano.

This volcano has been active for 500,000 years, and people who live in the vicinity have felt a few eruptions comparable to the very infamous Mount St. Helens that had basaltic lava coating the sides of the volcano. Medicine Lake is also part of the caldera, which is a bowl-shaped depression in the mountain. Seismologists found the volcano unique because it has several small magma chambers instead of a single, large one.

2. Mount Shasta Volcano

Mount Shasta is another "potentially" active volcano situated at the southern end of the Cascade Range. You can say that Medicine Lake and Mount Shasta are neighboring volcanoes. With an approximate elevation of 14,179 feet, this volcano is ranked second in peak elevation in the Cascade Range. Researchers also ranked it as the fifth in the state. It also has a lava volume of 5 cubic miles, about half of the Medicine Lake volcano.

Mount Shasta connects to a satellite cone, which is Shastina. Together, they form most of the landscape that you see around the Cascade Range. If you plan on checking the mountain, you need to visit it on a clear winter day from the Central Valley floor, 140 miles down south.

3. Lassen Volcanic Center

You can visit the Lassen Volcanic Center in Lassen Volcanic National Park, which is about 55 miles east of Redding. Hundreds of explosive eruptions happened within 850,000 years due to the vents spread over 200 miles. The volcano also has an elevation of 3,187 miles, making it a great tourist attraction. At least 350,000 people visit the Lassen Volcanic Center each year because of its unique volcanic landscapes.

The area around the Lassen Volcanic Center has had fifty non-explosive eruptions within the last 100,000 years and has been mostly dormant for the last 25,000 years. However, there are three exempted eruptions; the Chaos Crags eruption that happened 1,100 years ago, the Cinder Cone eruption in 1666 A.D., and the Lassen Peak eruption from 1914 to 1917 A.D.

4. Clear Lake Volcanic Field

The fourth active volcano on this list is the Clear Lake Volcanic Field. It is set about 90 miles north of San Francisco, precisely beside Clear Lake in California's northern Coast Ranges. It also has an elevation of 1,439, making it the volcano with the lowest elevation out of the other three mentioned above. The volcano's key point is that it has 43,000 acres of freshwater, which gives the volcano its name.

You can check out the Geysers steam field, which you can locate at the region's southwest margin. It can generate enough energy to power 850,000 homes since it has very productive geothermal power plants. The most recent eruption recorded in the Clear Lake Volcanic Field happened about 11,000 years ago near Mount Konocti. While it has laid dormant for several millennia, seismologists managed to detect sporadic earthquakes due to the volcano. They also found numerous volcanic gas and hot springs located within the area, giving seismologists the conclusion that it may erupt again.

5. Long Valley Volcanic Region

What's worse than having one volcano? Two volcanoes! When you visit the Long Valley Volcanic Region, you can spot the Long Valley Caldera and the Mono-Inyo Craters that form a large volcanic complex around eastern California. It was also the cause of considerable earthquake activity and ground uplift in the last decades.

The volcanoes' floor elevation ranges between 6,500 to 8,500 feet, which is close to the Medicine Lake Volcano. Seismologists estimate that the next eruption will be smaller and similar to the past eruptions that happened along the Mono-Inyo volcanic chain within the last 5,000 years.

6. Coso Volcanic Field

If you like looking at hot springs, you should check out the Coso Volcanic Field located about 100 miles northeast of Bakersfield, California, within the boundary of the Naval Air Weapons Station, China Lake. It covers roughly 150 miles of land and houses one of the largest energy-producing geothermal power plants in the United States. The power plant has a power output that can supply at least 270,000 homes.

The Coso Volcanic Field also has hot springs, boiling mud pots, and steam vents near the volcano center. Seismologists recorded at least 40 eruptions within the last quarter-million years. It also produced red hills of volcanic cinder, a field of steep-sided lava domes, and rough-surfaced lava flows. Seismologists also recorded small to moderate earthquakes because of the geothermal resource.

7. Salton Buttes

Finally, you have the seventh active volcano, or volcanoes, which is the Salton Buttes. It is a series of volcanoes on the Salton Sea in California. The Salton Buttes have a 4.3 mile-long row of five lava domes, which researchers named North Red Hill, Mullet Island, Rock Hill, South Red Hill, and Obsidian Butte. Seismologists even found evidence of buried volcanoes underneath the land.

Many eruptions happened 400,000 years ago until it became dormant about 18,000 years ago. The most recent eruption took place 1,800 years ago that started explosively, then slowly progressed into dense, glass-looking lava domes. As always, the United States used the Salton Buttes to gather geothermal power that currently generates power for 325,000 homes. There isn't enough available data for seismologists to figure out the volcanic activity's pattern, but there's still a possibility of future eruptions.

Whenever you take a trip to see these volcanoes, you may see some buildings beside them, like the Lava Beds National Monument. You can find some of these buildings have certain features like fire rated access doors. This one feature is critical whenever a building fire happens because it protects the building utilities from getting damaged from the fire. If you have construction projects that need fire rated access doors, make sure to contact California Access Doors.

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Get the right access doors for the standard of your commercial or industrial building. To know more about our high-quality access doors, check out our product page.

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"Beaches are perhaps the most iconic feature of California, and the potential for losing this identity is real. The effect of California losing its beaches is not just a matter of affecting the tourism economy. Losing the protecting swath of beach sand between us and the pounding surf exposes critical infrastructure, businesses and homes to damage. Beaches are natural resources, and it is likely that human management efforts must increase in order to preserve them," said lead author of the study, Sean Vitousek, who was a post-doctoral fellow at the U.S. Geological Survey when he conducted this study. Vitousek is now a professor in the Department of Civil & Materials Engineering at the University of Illinois at Chicago.

Although a majority (72 percent) of beaches in Southern California show historical trends of accretion or getting larger (due to large artificial beach nourishments since the 1930s), future predictions indicate that nearly all of the beaches will experience erosion (will get smaller) due to accelerated sea-level rise.

"Beaches in Southern California are a crucial feature of the economy, and the first line of defense against coastal storm impacts for the 18 million residents in the region. This study indicates that we will have to perform massive and costly interventions to preserve these beaches in the future under the erosive pressures of anticipated sea level rise, or risk losing many of the economic and protective benefits beaches provide," said USGS geologist and coauthor, Patrick Barnard.

Important for coastal hazard assessment and management planning, CoSMoS-COAST is a numerical model used to predict shoreline-change due to both sea level rise and changing storm patterns driven by climate change.

The model takes into consideration sand transport both along the beach (due to longshore currents) and across the beach (cross-shore transport) by waves and sea-level rise. Although Southern California beaches are a complex mixture of dunes, bluffs, cliffs, estuaries, river mouths, and urban infrastructure, the model is applicable to virtually any coastal setting. Additionally, the CoSMoS model uses information about historical shoreline positions and how beaches change in response to waves and climate cycles such as El Niño, to improve estimates and improve confidence in long-term prediction of coastline changes in Southern California.

Although shoreline change is very hard to predict, scientists are confident in the accuracy and reliability of the model's predictive capability applied to the forecast period (2010-2100), because of how accurately the model is able to reproduce the historical shoreline change between 1995 and 2010.

"The public already has to overcome obstacles in getting to the beach, from limited public transportation to illegally blocked pathways," said California Coastal Commission Executive Director John Ainsworth. "The prospect of losing so many our beaches in Southern California to sea level rise is frankly unacceptable. The beaches are our public parks and economic heart and soul of our coastal communities. We must do everything we can to ensure that as much of the iconic California coast is preserved for future generations."

The full report, " A model integrating longshore and cross-shore processes for predicting long-term shoreline response to climate change," is published online by the American Geophysical Union in their "Journal of Geophysical Research."

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Disappearing Beaches: Modeling Shoreline Change in Southern California

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"Beaches are perhaps the most iconic feature of California, and the potential for losing this identity is real. The effect of California losing its beaches is not just a matter of affecting the tourism economy. Losing the protecting swath of beach sand between us and the pounding surf exposes critical infrastructure, businesses and homes to damage.

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The California Geological Survey studies earthquakes to help Californians plan and build earthquake resistant communities. We record the strong ground motion from earthquakes, study the distribution of historic earthquakes and evaluate faults that are the source of earthquakes. We combine that information to prepare maps showing the potential for ground shaking, fault rupture, liquefaction and seismically induced landsliding.

Earthquake Probabilities

Earthquake probabilities are calculated by projecting earthquake rates based on earthquake history and fault slip rates. The result is expressed as the probability that an earthquake of a specified magnitude will occur on a fault or within an area. The Uniform California Earthquake Rupture Forecast represents the best available science for authoritative estimates of the magnitude, location, and likelihood of potentially damaging earthquakes in California.

Earthquake Shaking Hazards

Earthquake shaking hazards are calculated considering earthquake magnitudes and rates, the decrease in earthquake shaking with distance, and amplification of shaking by soils. The result is expressed as the level of ground shaking (as a percentage of gravity) that on average occurs every 2,500 years. These calculations for California are part of a cooperative project between USGS and CGS, and are part of National Seismic Hazard Maps.

Earthquake Loss Estimation

The effects of potential earthquakes are described by statewide earthquake loss estimation and planning scenarios. An earthquake planning scenario is a description of a hypothetical earthquake, including projected ground shaking, damage, social disruption and economic losses. The long term effects of possible earthquakes also can be estimated and described as annualized losses: the average loss or casualties per year. Earthquake loss estimation and planning scenarios provide useful information in preparing emergency response plans, developing earthquake hazard mitigation strategies, and evaluating the nature and scope of response and recovery efforts prior to the earthquakes.

What to do Before, During, and After an Earthquake

Knowing how to prepare for and survive a major earthquake will be critical in California sometime in the coming years.

How to Prepare

Plan on fending for yourself for at least three days, preferably for a week. Electricity, water, gas and telephones may not be working after an earthquake. The police and fire departments are likely to be tied up.

Decide in advance how and where your family will reunite if separated during a quake.Do in-home practice drills. You might choose an out-of-the-area friend or relative that family members can call to check on you.

What to do During an Earthquake

If you're indoors, stay there.Get under -- and hold onto --a desk or table, or stand against an interior wall. Stay clear of exterior walls, glass, heavy furniture, fireplaces and appliances. The kitchen is a particularly dangerous spot. If you're in an office building, stay away from windows and outside walls and do not use the elevator. Many are certain that standing in a doorway during the shaking is a good idea.That's false, unless you live in an unreinforced adobe structure; otherwise, you're more likely to be hurt by the door swinging wildly in a doorway or trampled by people trying to hurry outside if you're in a public place.

If you're driving, move the car out of traffic and stop. Avoid parking under or on bridges or overpasses. Try to get clear of trees, light posts, signs and power lines. When you resume driving, watch out for road hazards.

If you're in a mountainous area, beware of the potential for landslides. Likewise, if you're near the ocean, be aware that tsunamis are associated with large earthquakes. Get to high ground.

If you're in a crowded public place, avoid panicking and do not rush for the exit. Stay low and cover your head and neck with your hands and arms.

What to Do After an Earthquake

Check for fire or fire hazards. If you smell gas, shut off the main gas valve. If there's evidence of damage to electrical wiring, shut off the power at the control box.

Listen to the radio for important information and instructions. Remember that aftershocks, sometimes large enough to cause damage in their own right, generally follow large quakes.

If you leave home, leave a message telling friends and family your location.

Earthquake Frequently Asked Questions

What is an earthquake and what causes earthquakes?

An earthquake is a shaking of the ground caused by the sudden breaking and shifting of rock beneath the Earth's surface. Earthquakes occur when the two sides of a fault slip suddenly against each other. In California, the Pacific and North American plates creep past each other in opposite directions, about 1.5 inches per year. Friction between the plates causes some parts to snag, then break free in sudden, jerking movements. Those movements emit waves of energy that travel through the ground, causing the shaking you feel.

What is a fault?

A fault is a fracture in the crust along which one side has moved relative to the other side. Faults can be very small or hundreds of miles long. The earth's crust is composed of huge plates that are in slow but nearly constant motion. Part of California is on the Pacific Plate, and part is on the North American Plate. The San Andreas Fault, which runs from the Salton Sea in Imperial County to Cape Mendocino in Humboldt County, is the boundary between these plates. Sometimes one block of the crust moves up while the other moves down, sometimes they move horizontally in opposite directions (that's what's happening with the San Andreas Fault; Los Angeles is creeping closer to San Francisco). Some faults are well known and easy to spot, such as the San Andreas. Others are underground, with nothing on the surface revealing their presence (a blind thrust fault). The 1994 Northridge earthquake was caused by a blind thrust fault.

How common are faults in California?

There are hundreds of identified faults in California; about 200 are considered potentially hazardous based on their slip rates in recent geological time (the last 10,000 years). More than 70 percent of the state's population resides within 30 miles of a fault where high ground shaking could occur in the next 50 years.

Does California have more and bigger earthquakes than anyplace else?

Actually, Alaska has more earthquakes and the biggest ones in the U.S. The largest earthquake in history occurred in Chile (a magnitude 9.5 on May 22, 1960). The biggest earthquake in the contiguous 48 states was the magnitude 7.9 Fort Tejon quake on Jan. 9, 1857.

How often do earthquakes happen?

The National Earthquake Information Center (U.S.) reports 12,000-14,000 earthquakes a year around the world, or 35 a day. Throughout the world, there are one "great" (magnitude 8.0 or more), 18 "major" (7.0-7.9), 120 "large" (6.0-6.9) and 1,000 "moderate" (5.0-5.9) earthquakes in an average year. Each year, California generally gets two or three earthquakes large enough to cause moderate damage to structures (magnitude 5.5 and higher). Earthquakes can occur at any time of the year.

What is an earthquake's hypocenter? What is the epicenter?

Earthquake ruptures usually begin far under the surface of the Earth. The point on a fault where rupture initiates is referred to as the focus or hypocenter of an earthquake. The hypocenter is described by its depth in kilometers, its map location in latitude and longitude, its date and time of occurrence, and its magnitude (a measure of the amount of energy radiated as seismic waves). The term epicenter, which is more commonly used to refer to an earthquake location, is the point on the earth's surface directly above the hypocenter. The description of an epicenter is the same as for a hypocenter except the depth is omitted.

How are earthquakes recorded and measured?

There is a network of seismic monitoring stations throughout California and in other parts of the country and world. Sensors and recorders in each station measure and record ground vibrations produced by earthquakes. They measure acceleration, velocity, and displacement on three axes of motion--horizontal (x, y), and vertical (z). They transmit the information to computers which further process the data. The data from multiple stations enable us to determine the time, epicenter, and focal depth of an earthquake. Also, estimates can be made of an earthquake's relative intensity and amount of energy it released.

How much power does an earthquake release?

The strength of an earthquake is generally expressed in two ways: magnitude and intensity. The magnitude is a measure that depends on the seismic energy radiated by the earthquake as recorded on seismographs. An earthquake's magnitude is expressed in whole numbers and decimals (e.g., 6.8). The intensity at a specific location is a measure that depends on the effects of the earthquake on people or buildings. Intensity is expressed in Roman numerals or whole numbers (e.g., VI or 6). Although there is only one magnitude for a specific earthquake, there may be many values of intensity (damage) for that earthquake at different sites.

A magnitude 6.0 quake releases approximately as much energy as 6,270 tons of TNT, a magnitude 7.0 199,000 tons, a magnitude 8.0 6.27 million tons and a magnitude 9.0 99 million tons. Of course, all that energy is not focused in one particular spot, but spreads out in waves.

What factors influence what you feel in an earthquake?

There are three major factors: magnitude, your distance from the fault, and local soil conditions. Magnitude is discussed above. As for distance, the seismic waves that cause the shaking become less intense farther from the fault. Certain soil conditions amplify the shaking; generally, the looser the soil, the greater the amplification. Although most of San Francisco escaped serious damage in Loma Prieta, those with unconsolidated landfill or soft soils (such as the Marina District) suffered serious damage. The ground motion in such areas was 10 times stronger than at neighboring sites on rock.

What is a tsunami?

Sometimes called seismic sea waves (or, incorrectly, tidal waves), a tsunami is a series of waves generated by large earthquakes that create vertical movement on the ocean floor. Tsunamis can reach more than 50 feet in height, move inland several hundred feet and threaten life and property. Often, the first wave of a tsunami is not the largest. Tsunamis can occur on all coastal regions of the world, but are most common along margins of the Pacific Ocean. Tsunamis can travel from one side of the Pacific to the other in a day, at a velocity of 600 miles an hour in deep water. A locally generated tsunami may reach the shore within minutes.

Can earthquakes be prevented?

There's no way to stop an earthquake, but there are ways to build safer buildings and structures and otherwise be prepared for them. Building codes in California are updated often as new information comes in. While earthquakes are a deadly threat, there have been few earthquake-related deaths in California relative to places with less stringent codes or enforcement, such as Turkey and China.

Sources: California Geological Survey/California Geology, USGS, Arkansas Center for Earthquake Education and Technology Transfer, Governor's Office of Emergency Services, Federal Emergency Management Agency, National Science Foundation, Southern California Earthquake Center, American Red Cross, Center for Earthquake Research and Information/University of Memphis.

Earthquake Myths

If the Earth moves beneath our feet, is it because Atlas shrugged? In a bygone era, some folks may have believed that theory, but even today there are earthquake anecdotes that aren't exactly the stuff of modern science. Let's take a look at them:

MYTH: Dogs and other animals can "sense" when an earthquake is going to strike

It's impossible to determine whether a dog is behaving in an unusual manner because it smells an earthquake coming or a cat across the street. Changes in animal behavior sometimes have been observed prior to earthquakes, but that behavior is not consistent, and sometimes there's no perceptible behavior change prior to an earthquake.

MYTH: Earthquakes occur during "earthquake weather"

The common misconception that earthquakes occur during hot and dry weather dates to the ancient Greeks. Earthquakes take place miles underground, and can happen at any time in any weather.

MYTH: Big earthquakes always occur early in the morning

Just as earthquakes don't care about the weather, they can't tell time. The 1940 Imperial Valley quake was at 9:36 p.m., the 1989 Loma Prieta quake at 5:02 p.m. People who perpetuate the time and weather myths tend to remember the earthquakes that fit the pattern and forget about the ones that don't.

MYTH: California could fall into the sea because of an earthquake

The San Andreas Fault System is the dividing line between two tectonic plates. The Pacific Plate is moving in a northwesterly direction relative to the North American plate. The movement is horizontal, so while Los Angeles is moving toward San Francisco, California won't sink. However, earthquakes can cause landslides, slightly changing the shape of the coastline.

MYTH: The ground can open up and swallow people

You've seen the image in books, movies and TV shows. That's not how it works. If a fault could open up, there wouldn't be any friction. Without friction, there's no earthquake. But earthquakes cause settling and other ground deformation that can include open fissures into which people, cars, etc., can fall.

MYTH: The safest place to be in an earthquake is under a doorway

That's true only if you live in an unreinforced adobe home. In a modern structure the doorway is no stronger than the rest of the building. Actually, you're more likely to be hurt (by the door swinging wildly) in a doorway. And in a public building, you could be in danger from people trying to hurry outside. If you're inside, get under a table or desk and hang on to it.

MYTH: Small earthquakes keep big ones from happening

Each magnitude level represents about 31.6 times more energy released. It takes 32 magnitude 3s to equal the energy released in a magnitude 4, 1,000 magnitude 3s to equal a magnitude 5 ... and a billion magnitude 3s to equal a single magnitude 9. So while a small quake may temporarily ease stress on a fault line, it does not prevent a large temblor.

MYTH: The magnitude of an earthquake determines whether disaster assistance is forthcoming

A magnitude 7 quake in the middle of the desert is likely to do less damage than a magnitude 6 in downtown Los Angeles or San Francisco. It is the magnitude of the damage, not the earthquake, which determines the level of response.

MYTH: We have good building codes, so we must have good buildings

That's true -- provided you're talking about buildings constructed under current building codes. In the case of older buildings, retrofitting -- bringing the building up to modern standards -- is up to the building's owners. There are plenty of buildings in areas of California prone to seismic activity which were built under older codes.

MYTH: Earthquakes are becoming more frequent

Research shows that earthquakes of magnitude 7.0 or greater have remained fairly constant throughout recorded history and have actually decreased in recent years. However, since there are a greater number of seismological centers and instruments capable of locating many small earthquakes that went undetected in earlier years, it may seem as if there are more.

MYTH: There's nothing we can do to protect ourselves from earthquakes

It's true that earthquakes can't be stopped, but you can be prepared. You can put together an earthquake kit (food, water, flashlight, etc.), practice "drop, cover and hold on" drills at home with your family and at work, and develop an earthquake plan (where would you meet family members if you weren't together when an earthquake hit?). Also, remember that standard homeowners insurance doesn't cover damage from earthquakes. For information about earthquake insurance, visit the California Earthquake Authority.

Sources: California Geological Survey/California Geology, USGS, Arkansas Center for Earthquake Education and Technology Transfer, Governor's Office of Emergency Services, Federal Emergency Management Agency, National Science Foundation, Southern California Earthquake Center, American Red Cross, Center for Earthquake Research and Information/University of Memphis.

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California Department of Conservation administers a variety of programs vital to California's public safety, environment and economy. The services DOC provides are designed to balance today's needs with tomorrow's obligations by fostering the wise use and conservation of energy, land and mineral resources.

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Eruption in 1915

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This 20-minute film provides a brief introduction to Lassen Volcanic National Park. It is normally only shown in park visitor centers and is being provided online for a limited time during COVID-19 response. The film was funded by Lassen Park Foundation (lassenparkfoundation.org) through donations from visitors like you.

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Tom Bean/Corbis

Amos and colleagues' study suggests that seasonal and decadal water extraction in the nearby southern Central Valley stresses the San Andreas Fault system, causing variations in seismicity and promoting future earthquakes.

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Figure 1: Aerial view of the San Andreas Fault along the Carrizo Plain, central California.

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Tom Bean/Corbis Amos and colleagues' study suggests that seasonal and decadal water extraction in the nearby southern Central Valley stresses the San Andreas Fault system, causing variations in seismicity and promoting future earthquakes.

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Shows coastal Erosion

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WATCH: Pacifica Coastal Erosion Caught on Drone Video

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San Francisco Earthquake 1989

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Summary

Mount Shasta began forming on the remnants of an older, similar volcano that collapsed 300,000 to 500,000 years ago. The collapse spawned one of the largest landslides known on Earth, covering more than 440 km ² (170 mi ²) of Shasta Valley to the northeast. Activity over the last 300,000 years includes long intervals of quiet interrupted by shorter spans of frequent eruptions. Eruptions at about 11,000 years ago built Black Butte and Shastina on the western flanks of Mount Shasta. In the last few millennia, smaller eruptions have broken out at the volcano's summit and from vents on its upper east flank. USGS scientists are working on constraining the age of the most recent eruption. Preliminary work indicates the volcano erupted in the past 200-300 years. Hot springs and volcanic gases seep from the summit indicating a relatively young and still-hot system. Non-volcanic shedding of young volcanic rock and ash from Mount Shasta's steep slopes occurs during heavy rainfall or glacial floods. In the last 1,000 years, more than 70 mudflows have inundated stream channels. The record of eruptions over the last 10,000 years suggests that, on average, at least one eruption occurs every 800 to 600 years at Mt Shasta. USGS and UNAVCO seismic and geodetic networks provide real-time volcano monitoring data. Earthquake activity has been low for the last few decades and ground deformation is negligible.

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Mount Shasta began forming on the remnants of an older, similar volcano that collapsed 300,000 to 500,000 years ago. The collapse spawned one of the largest landslides known on Earth, covering more than 440 km 2 (170 mi 2) of Shasta Valley to the northeast.

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Possible lands slides near coast California

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Description:

This dataset includes: The locations of EPA listed sites that are vulnerable to a 100-year coastal flood with a 1.4 meter sea-level rise. Extents of dune and bluff erosion given a 1.4 meter (approx. 55") sea-level rise for the entire California coast. Extent of a 100-year coastal flood, based on FEMA 100-year flood elevations, with a sea-level rise of 1.4 meters (55 inches) (year 2100). Extent of inundation due to Mean Higher High Water (MHHW), after a 1.4 meter sea-level rise (scenario for year 2100), for the California coast (excluding the San Francisco Bay). The current inundation due to MHHW was based on NOAA tide stations elevation data (mhhw_2000 raster), to which 140 centimeters were added to the Z-value to generate this data. For details concerning methods, see the OPC SEA LEVEL RISE COASTAL EROSION MAPPING document from Philip Williams and Associates, LTD, from December 18th, 2008.

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California Sea Level Rise Coastal Erosion Mapping

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This dataset includes: The locations of EPA listed sites that are vulnerable to a 100-year coastal flood with a 1.4 meter sea-level rise. Extents of dune...

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Damage done by Mount Saint Helens Volcanic Eruption

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Damage done by Mount Saint Helens Volcanic Eruption

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Interactive Map Earthquakes where you live

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Interactive Map Earthquakes where you live

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Reported California Landslides Database

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Rockslide on California State Route 70 in the Feather River Canyon, Butte/Plumas county line, northern California. This slide was triggered on October 24, 2021 by a Category 5 atmospheric river, which released more than ten inches of rain in the area over a 48-hour period. Approximately seven thousand cubic yards of rock and debris buried and closed the highway; blasting was required to remove the larger slabs of granite from the roadway. Click/tap the image to open a high-resolution version of the entire scene.
Photo credit: Scott Tikalsky, California Department of Transportation.

In this section:

The California Geological Survey classifies landslides with a two-part designation based on Varnes (1978) and Cruden and Varnes (1996). The designation captures both the type of material that failed and the type of movement that the failed material exhibited.

Material types are broadly categorized as either rock or soil, or a combination of the two for complex movements. Rock refers to hard or firm bedrock that was intact and in place prior to slope movement. Soil, either residual or transported material, is used in the engineering sense to mean unconsolidated particles or poorly cemented rock or aggregates. Soil is distinguished further on the basis of texture as debris (coarse fragments) or earth (fine fragments). The distinction between rock and soil, and the further distinction between debris and earth is most often based on interpretation of geomorphic characteristics within landslide deposits, but can also be inferred from geologic characteristics of the parent material described on maps or observed in the field.

Landslide movements are interpreted from the geomorphic expression of the landslide deposit and source area, and are categorized as falls, topples, spreads, slides, or flows. Falls are masses of soil or rock that dislodge from steep slopes and free-fall, bounce, or roll downslope. Topples move by the forward pivoting of a mass around an axis below the displaced mass. Lateral spreads, commonly induced by liquefaction of material in an earthquake, move by horizontal extension and shear or tensile fractures. Slides displace masses of material along one or more discrete planes. In rotational sliding the slide plane is curved and the mass rotates backwards around an axis parallel to the slope; in translational sliding the failure surface is more or less planar and the mass moves parallel to the ground surface. Flows mobilize as a deforming, viscous mass without a discrete failure plane. More than one form of movement may occur during a failure, in which case the movement is classified as complex if movements occur sequentially and composite if they do not.

Five of the 20 possible material/movement combinations are commonly found when preparing a landslide inventory map. These are earth flows, debris flows, debris slides, rock slides, and rock falls, and are described in more detail below.

Earth Flows

Diagram by J. Appleby, R. Kilbourne, and C. Wills after Varnes, 1978

An earth flow is a specific type of soil flow landslide where the majority of the soil materials are fine-grained (silt and clay) and cohesive. The material strength is low through much of the slide mass, and movement occurs on many discontinuous shear surfaces throughout the landslide mass. This movement along numerous internal slide planes disrupts the landslide mass leading to cumulative movement that resembles the flow of a viscous liquid characterized by a lumpy, or "hummocky" slope morphology. The lower parts of an earth flow usually bulge outward and are steeper than adjacent slopes.

Earth flows commonly occur on moderately steep slopes. Slope gradients are commonly from 10% to as steep as 30%, although steeper slopes may be found in headscarp and toe areas.

Earth flows typically are initiated by periods of prolonged rainfall and sometimes don't initiate until well after a storm or the rainy season has passed. They are characteristically slow moving, in the millimeters or centimeters per day range, and may continue to move for a period of days to weeks after initiating.

Debris Flows

Diagram by J. Appleby and R. Kilbourne, CGS

A debris flow is a soil flow where the majority of the materials are coarse-grained (fine sand to boulder size particles) and non-cohesive. Debris flows are most often triggered by intense rainfall following a period of less intense precipitation, or by rapid snow melt. High pore water pressures cause the soil and weathered rock to rapidly lose strength and flow downslope. Debris flows can move very rapidly, at rates ranging from meters per hour to meters per second and travel relatively long distances, making them a significant threat to life and property.

Debris flows commonly begin as a slide of a shallow mass of soil and weathered rock. Their most distinctive landform is the scar left by the original shallow slide. The path of the debris flow may be marked by a small drainage that has been stripped of vegetation. The debris flow may not leave any deposit if it flows directly into a larger creek and is immediately eroded away. Many debris flow deposits are ephemeral, but in some cases successive debris flows may deposit material in the same area thereby forming a debris fan, which resembles a small, steep alluvial fan.

Individual debris flows typically are small in areal extent and their deposits are relatively thin. Evidence of past debris flow movements often is masked by vegetation growth which can cover the surface rapidly, sometimes within a few years, making them difficult to identify using aerial photographic and field reconnaissance methods. Therefore, only the larger and more recent debris flows typically are identified and included on landslide inventory maps.

Debris Slides

Diagram by J. Appleby, R. Kilbourne, and C. Wills after Varnes, 1978

A debris slide is a landslide of coarse-grained soil, most common in unconsolidated sandy or gravelly units, but also are common in residual soils that form from in-place weathering of relatively hard rock. Owing to the granular constituents, overall strength of the debris slide mass generally is higher than that of earth flows, but there may be a very low strength zone at the base of the soil or within weathered bedrock. Debris slides typically move initially as shallow intact slabs of soil and vegetation, but break up after a short distance into falls and flows. Movement of the slide mass as a shallow slab leads to a smooth, steep, commonly curved scar. The debris is deposited at the base as a loose hummocky mass, although the deposit may be rapidly removed by erosion.

Debris slides commonly occur on very steep slopes, as steep as 60% to 70%, usually in an area where the base of a slope is undercut by erosion. Debris slides form steep, un-vegetated scars which are likely to remain un-vegetated for years. Re-vegetated scars can be recognized by their steep slopes, and a shallow amphitheater morphology.

A single heavy rainstorm or series of storms may deliver enough rain to trigger debris slides. Individual debris slides may move at rates ranging from meters per day to meters per minute. Debris slide scars are extremely steep and therefore are very sensitive to renewed disturbance. Natural erosion at the base of debris slide scars may trigger additional slides. Cutting into the base of a debris slide scar may also trigger renewed slides. Even without additional disturbance, debris slide scars tend to ravel and erode, leading to small rock falls and debris slides from the same slope.

Rock Slides

Diagram by J. Appleby, R. Kilbourne, and T. Spittler after Varnes, 1978

A rock slide is a landslide involving bedrock in which the rock that moves remains largely intact for at least a portion of the movement. Rock slides can range in size from small and thin to very large and thick, and are subject to a wide range of triggering mechanisms. The sliding occurs at the base of the rock mass along one to several relatively thin zones of weakness, which are variably referred to as "slide planes," "shear surfaces," "slip surfaces," "rupture surfaces," or "failure surfaces." The sliding surface may be curved or planar in shape. Rock slides with curved sliding surfaces are commonly called "slumps" or "rotational slides," while those with planar failure surfaces are commonly called "translational slides," "block slides," or "block glides." Rock slides that occur on intersecting planar surfaces are commonly called "wedge failures.

Rock slides commonly occur on relatively steep slopes in competent rocks. Slope gradients are commonly from 35% to as steep as 70%. Movement of an intact rock mass along a curved slide plane leads to a steep, arcuate headscarp at the upper boundary of the slide. Immediately below the headscarp is a block that is commonly rotated so that it is less steep than the surrounding hill slopes. Below the bench, the slide mass may be intact with a similar gradient to the surrounding slopes or may have additional scarps and benches. The lower parts of the slopes may bulge outward and be steeper that the surrounding slopes.

Rock Falls

Diagram modified after Colorado Geological Survey

A rock fall is a landslide where a mass of rock detaches from a steep slope by sliding, spreading or toppling and descends mainly through the air by falling, bouncing or rolling. Intense rain, earthquakes or freeze-thaw wedging may trigger this type of movement.

Rock falls occur on steep slopes of hard, fractured rock. The scar left by a rock fall on the slope may be no more apparent than an area of rock that is less weathered than the surrounding rocks. Rock fall deposits are loose piles of rubble that may be easily removed by erosion. Because neither the scar nor the deposit are distinctive, and because the most frequently occurring rock falls are typically small, individual rock falls are usually not shown on regional-scale (1:24,000 and smaller) landslide maps.

Though infrequent, moderate- to large-volume rock falls can be extremely dangerous and sometimes fatal. Large slabs of rock impacting a hard ledge after a long drop can rapidly break apart, leading to air entrainment and long runouts, induced airblasts, airborne projectiles (flyrock) and severe dust clouds.

In this section:

Since the 1960's, the California Geological Survey (CGS) has produced numerous maps that show landslide features and delineate potential slope-stability problem areas. Preparation of these maps has been episodic, often driven by landslide disasters and subsequent legislative mandates. Many CGS landslide maps and related products have been produced for local or state agencies in response to their specific needs.

To find the landslide map that covers your area of interest, please see our Landslide Map Index. Refer to the explanation on that map and descriptions of the types of landslides and types of landslide maps for details on how landslides are mapped and described.

Types of Landslide Maps

Four principal types of information describing the various classes of landslides are portrayed by different landslide maps prepared by the California Geological Survey: (1) inventories of existing landslides, (2) landslide hazard-expressed as landslide susceptibility or landslide potential maps, (3) landslide risk maps, and (4) landslide zone maps. The maps can be either qualitative or quantitative in their preparation.

1. Landslide-inventory maps, the most basic landslide maps, portray the location of prior failure. Because one clue to the location of future landsliding is the distribution of past movement, maps that show existing landslides are helpful in predicting the hazard. Inventory maps do not necessarily distinguish fresh movements, but in any one year some of the mapped slides-or more frequently, portions of them-may become active. A landslide inventory reveals the extent of past movement and thus the probable locus of some future activity within those landslides, but it does not indicate the likelihood of failure for the much larger area between mapped landslides. For this, hazard, risk or zone maps are required.

2. Landslide-hazard maps describe an unstable condition arising from the presence or likely future occurrence of slope failure. There are two general types of landslide-hazard maps, each of which provides a different level of information and detail:

1. Landslide-susceptibility maps describe the relative likelihood of future landsliding based solely on the intrinsic properties of a locale or site. Prior failure (from a landslide inventory), rock or soil strength, and steepness of slope are the three site factors that most determine susceptibility.

2. Landslide-potential maps describe the likelihood of landsliding (susceptibility) jointly with the occurrence of a triggering event (opportunity). Potential commonly is based on the three factors determining susceptibility plus an estimate or measure of the probability (likelihood of occurrence) of a triggering event such as earthquake or excessive rainfall.

3. Landslide-risk maps describe landslide potential jointly with the expected losses to life and property if a failure was to occur. The potential for landslide damage to a road system, for example, can be evaluated by considering the exposure of the roads to different levels of landslide hazard and the vulnerability of the roads to consequent damage. Similarly, the risk of excessive sedimentation in streams and other ecological damage can be evaluated by considering the landslide hazard jointly with the properties of streams and their sensitivity.

4. Landslide-zone maps depict areas with a higher probability of landsliding, within which specific actions are mandated by California law prior to any development. These maps typically are binary in nature (a given site is either in or out of the zone) and are designed for use as planning tools by non-geoscientists. Zone maps may be derived from landslide potential or susceptibility, but some have been based simply on slope gradient or landslide-inventory maps.

Landslide hazard, risk and zone maps are prepared in many ways, increasingly involving complex manipulations of multiple criteria by computer. Because the value of landslide maps can be judged only by whether they correctly predict the locations of future failures, effectiveness of the different approaches to constructing them is difficult to evaluate.

Categories of Landslide Activity

Each landslide is classified based on the recency of activity into one of four categories based on the system of Keaton and DeGraff, (1996). The landslide activity categories are graphically portrayed with the colors used to delineate landslide activity on the maps. The designation of activity shows an estimate of how recently the landslide moved, but also suggests the type of hazard represented. More recently active landslides are more likely to continue to fail, or to fail completely. Older landslides are less likely to move as single slide masses, but may be the source of smaller slides.

Cited References

Cruden, D.M., and Varnes, D.L. 1996, Chapter 3: Landslide types and processes, pp. 36-75 in A.K. Turner and R.I. Schuster (eds.), Landslides: Investigation and Mitigation, Special Report 247, Transportation Research Board, National Research Council, Washington D.C.: National Academy Press.

Keaton, J.R., and DeGraff, J.V., 1996, Surface observation and geologic mapping, in Turner, A.K., and Schuster, R.L., editors, Landslides Investigation and Mitigation: National Research Council Transportation Research Board Special Report 247, p.178-230.

Varnes, D.J., 1978, Slope movement types and processes. In, R.L. Schuster and R.J. Krizek (eds.), Landslides: Analysis and Control, National Research Council Transportation Research Board Special Report Special Report 176, National Research Council, Washington, D.C. pp. 11-33.

In this section:

History of Landslide Mapping at CGS

In the 1970's, CGS prepared a series of "Geology for Planning" and "Environmental Geologic Analysis" reports and maps for local agencies in urbanizing areas. These products were designed to assist local agencies in evaluating hazards and developing policies that consider landslide hazards as residential development spread into landslide-prone terrain.

Following the 1982 El Nino storms in the San Francisco Bay area, the Landslide Hazard Mapping Act mandated new maps to show landslides and landslide hazards. Landslide Hazard Identification Maps were prepared by CGS for use by local government planners from 1986 to 1995. A set of three to four maps was prepared for each map study area, usually encompassing a USGS 7.5-minute topographic quadrangle map. The set of maps typically consisted of a geologic map, a landslide inventory map - showing the location and distribution of existing landslides - and one or two landslide relative susceptibility maps.

Also beginning in the early 1980's, concerns about the long-term ecologic impacts of timber harvesting lead to the mapping of landslide features in forested lands. Maps developed under this program include landslide inventory maps, and depict other geomorphic features (e.g. debris-slide slopes and inner gorges) where shallow landsliding is a dominant mode of mass wasting.

Although the Geology for Planning, Environmental Geologic Analysis, and Landslide Hazard Identification programs are no longer in existence, their products are generally still available as paper prints or pdfs and most of the landslides from those maps have been included in the California Landslide Inventory, discussed in the next section.

Currently active landslide mapping programs at CGS, and their respective products, are summarized below.

The California Landslide Inventory is an ongoing project to collect and display landslide data for the State of California. These data include both the most recently mapped landslides and data developed over the past thirty years by the California Geological Survey and its collaborators. Multiple programs at the CGS create landslide data. Historically, each program created its own data standard to meet its specific needs. Between 2012 and 2015, the landslide mapping programs at CGS developed a common data standard for developing landslide data. These data have now been standardized into the Landslide Inventory, and new data will be developed in accordance with the Landslide Inventory's data standard.

The California Geological Survey is in the process of digitizing maps of landslides and has prepared a statewide landslide map database that is available online. The database shows many of the landslides mapped by CGS and others over the past 50 years. Mapping of landslides reflects the standards of the project and time the map was prepared. Many maps show landslide source areas (scarps) separate from landslide deposits, other maps combine scarps and deposits into a single feature. The amount of information recorded about each landslide has increased over time, so more information is available for more recently mapped landslides. Updates to the database are continuing, both to include more existing maps and to add current landslides as they occur. The landslide inventory, in combination with the map of susceptibility to deep-seated landslides ( CGS Map Sheet 58) can give local planners, infrastructure owners, and the public a perspective on where landslides are most likely to be triggered by winter storms or by earthquakes in California. View the California Landslide Inventory.

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California Department of Conservation administers a variety of programs vital to California's public safety, environment and economy. The services DOC provides are designed to balance today's needs with tomorrow's obligations by fostering the wise use and conservation of energy, land and mineral resources.

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2020 Fire Year

The 2020 California wildfire year was characterized by record-setting wildfires that burned across the state of California as measured during the modern era of wildfire management and record keeping. As of the end of the year, nearly 10,000 fires had burned over 4.2 million acres, more than 4% of the state's roughly 100 million acres of land, making 2020 the largest wildfire season recorded in California's modern history. California's August Complex fire has been described as the first "gigafire" as the area burned exceeded 1 million acres. The fire crossed seven counties and has been described as being larger than the state of Rhode Island. On August 19, 2020, California Governor Gavin Newsom reported that the state was battling 367 known fires, many sparked by intense thunderstorms on August 16-17. In early September 2020, a combination of a record-breaking heat wave, and Diablo and Santa Ana winds sparked more fires and explosively grew the active fires, with the August Complex more than doubling the Mendocino Complex's size to become California's largest recorded wildfire.

Pictured: The LNU Lightning Complex which burned across wine country in August 2020.

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Photo USGS Mt. St. Helens, Washington
Cascade Range Volcanoes and Volcanics - Current Updates
"More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the last 10,000 years. ... Sooner or later, volcanoes in California will erupt again, and they could have serious impacts on the health and safety of the State's citizens as well as on its economy." Miller, C. Dan (USGS)

"California is the most geologically diverse state in the nation. We are known for our earthquakes, landslides and flood hazards. But our nearly forgotten hazard is our volcanoes," said Dr. John Parrish, the State Geologist of California. (USGS)

USGS Photograph taken by Lyn Topinka, 1984
Mt Shasta Cam
Mount Shasta
Elevation: 14,162 feet
Location: Northern
California, USA

May 22, 1915 eruption -Photo: R.E.Stinson
Mount St. Helen's Cam
Mount St. Helen's
Elevation: 4,500 feet
Location: Washington State/Johnston Ridge Observatory

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Landslide Inventory and Deep-Seated Landslide Susceptibility

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California is host to every type of volcano. The specific hazards to people and property depend on which volcano erupts, the style (effusive or explosive), the volume of lava, the location of the vent, the eruption duration, and local hydrologic (water) conditions. The severity of the hazard generally decreases with distance from the volcano vent.

Threat rankings issued by the U.S. Geological Survey (USGS) for California identify fifteen volcanic centers of Low-, Moderate-, High-, or Very High Threat. The USGS California Volcano Observatory (CalVO) is responsible for assessing the potential hazards associated with these "watch list" volcanoes and providing civil authorities, as well as the public, with timely and accurate information to mitigate, plan, and respond effectively to volcanic activity.

At least seven California volcanoes-Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes - have partially molten rock (magma) deep within their roots, and research on past eruptions indicates they will erupt again in the future. The types of volcanic hazards that can unfold depend upon the specific volcano and the type of eruption.
Explosive eruptions are both destructive and life-threatening
Explosive volcanic eruptions blast lava fragments (tephra) and gas into the air with tremendous force from a volcanic vent. The finest particles, called volcanic ash, billow upward, forming an eruption column that can attain stratospheric heights in minutes. Simultaneously, searing volcanic gas laden with ash and chunks of lava may sweep down the flanks of the volcano as a pyroclastic flow, and ballistics (chunks of solid rock or partially molten lava) may come crashing down around the vent. Ash in the eruption cloud, carried by the prevailing winds, may remain suspended for hundreds of miles before settling to the ground as ash fall.
Effusive eruptions can be destructive, but are typically not life-threatening
During less energetic effusive eruptions, hot, fluid lava may issue from the volcano as lava flows that can cover many miles in a single day. Alternatively, a sluggish plug of cooler, partially solidified lava may push up through a crack during an effusive eruption, creating a lava dome. A growing lava dome may become so steep that it collapses, explosively releasing pyroclastic flows which are potentially as hazardous as those produced during explosive eruptions.
Volcanoes can be hazardous even when not erupting
During and after an explosive or effusive eruption, volcanic hazards are still a concern. Unstable ground, noxious gas emissions, and intense heat from fumaroles (steam vents) and hot springs, are dangerous. Loose volcanic debris on the flanks of the volcano can be mobilized by heavy rainfall or melting snow and ice, forming powerful floods of mud and rock (lahars) resembling rivers of wet concrete. These can rush down valleys and stream channels, destroying roads and bridges and carrying away entire buildings.
Volcanic hazard maps inform planning and decision making
Geologists produce volcanic hazard zone maps and assessments to show the types and locations of hazards that may occur during a future eruption. The USGS has published such maps for some, but not all, of California's Moderate to Very High Threat volcanoes. It is important to remember that hazard zone maps are dynamic-as geologic research progresses, existing maps are updated with additional detail, and new maps are created.

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California has active and hazardous volcanoes

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California is host to every type of volcano. The specific hazards to people and property depend on which volcano erupts, the style (effusive or explosive), the volume of lava, the location of the vent, the eruption duration, and local hydrologic (water) conditions. The severity of the hazard generally decreases with distance from the volcano vent.

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A series of atmospheric rivers struck California during the week of Jan. 9, causing floods, landslides, power outages and more across the state. (Video: John Farrell/The Washington Post)

A parade of storms known as atmospheric rivers has dumped massive amounts of rain and snow on California since late December. The storms have produced deadly flooding, crippling snow, dangerous mudslides, severe thunderstorms and tornadoes.
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Here are five images that help demonstrate the breadth and power of the storms - part of a weather pattern that could continue for another week or more.
An atmospheric river event for the ages
Atmospheric rivers funnel extreme amounts of moisture over the oceans into narrow bands of clouds. As these clouds are transported over land, they can produce many hours of intense rain and snow.

Precipitable water is an indicator of how much moisture there is in the atmosphere. Higher values of precipitable water correspond to greater potential for heavy rain or snow. The animation of precipitable water forecast above, which spans Jan. 9 to 23, shows the parade of multiple atmospheric rivers lashing California with repeated rounds of heavy rain and snow.

The darkest shades of red and brown represent precipitable water values 200 to 250 percent of normal.
The awe of a bomb cyclone

Atmospheric river approaches California. (Video: NOAA)

As is often the case, the worst weather Mother Nature has to offer can often be beautiful when viewed from high above. In this view captured by the National Oceanic and Atmospheric Administration's GOES-18 weather satellite, the low-pressure center of last week's "bomb cyclone" can be seen spinning over the Pacific Ocean as it approaches the West Coast from Jan. 3 to 4.

The bomb cyclone, which is a rapidly intensifying storm whose central pressure drops at least 24 millibars in 24 hours, was one of a series of powerful storms that has repeatedly thrust atmospheric rivers into California in recent weeks. It was only a few weeks ago that a different bomb cyclone developed along the Arctic front, blasting much of the country with extreme cold and some areas with blizzard conditions.
Historic rainfall hammers California
The atmospheric rivers have deluged California with copious amounts of rain. In just the past two days, ending at 4 a.m. Tuesday, areas of higher terrain in Ventura and Santa Barbara counties have seen more than 16 inches of rain. The 12.37 inches of rain in San Francisco between Dec. 26 and Jan. 9 qualifies as the third-wettest 15-day period since 1849, according to Bay Area meteorologist Jan Null.

During this period, Sacramento recorded more than 8 inches of rain, and Los Angeles registered more than 4 inches.

The extreme rainfall, which is expected to continue until the expected end of the pattern around Jan. 20, has caused widespread and severe flooding, road closures and mudslides. While the unrelenting rain is wreaking havoc in the short term, it is combining with snow to help put a significant dent in the drought that has long plagued the region.

California is being inundated with rain. Will it ease the drought?
Surging snowpack across the Sierra Nevada
Snowpack across much of the central and southern portions of the Sierra Nevada is now 200 to 300 percent of normal for the date, as shown in the map above. In some locations the snowpack has already exceeded the April 1 average. (April 1 is typically around the time the snowpack is at its deepest.)

The growing snowpack is helping to ease California's years-long drought. The most recent U.S. Drought Monitor, released Jan. 5, upgraded central to southern portions of the state from the most severe level, D4 (exceptional drought), to D3 (extreme drought). Additional rain and snow in the next week or so could further ease drought conditions across California.
Raging rivers rise out of their banks
After multiple years of drought, too much rain falling too fast has pushed multiple rivers beyond flood stage. One of the more extreme forecasts is for the Salinas River. The visual above shows that where the river runs near Spreckels in Monterey County, the water level is expected to reach or exceed 30 feet, which is about seven feet above flood stage.

The effects of heavy rain and flooding have been catastrophic, and at least 17 deaths have been attributed to the storms since late December. Rivers that were recently, currently or soon expected to be above flood stage as of Tuesday afternoon include the Russian River, the Salinas River, the Carmel River, the Santa Ynez River and Bear Creek, according to the California Nevada River Forecast Center.

Thunderstorms and hail hit the San Francisco Bay on Jan. 10 as another "atmospheric river" brought more severe weather to California. (Video: Reuters)

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Maps and charts show the awful impact of the California storms

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The rainfall from atmospheric rivers, set to continue until around Jan. 20, has caused widespread damage, flooding, road closures and mudslides in California.

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California's Cliffs Crumbling into the Sea

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California's Cliffs Crumbling into the Sea

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Coastal cliffs in California's far northern counties are eroding faster than those elsewhere in the state, according to a new study that used high-resolution data to pinpoint hot spots where cliffs are receding rapidly along the state's entire coast.

In the Bay Area, locations with some of the highest rates of clifftop erosion include Daly City, Pacifica and Bodega Bay, according to the study published this month by researchers at Scripps Institution of Oceanography at UC San Diego. The highest erosion rates were found near Humboldt Bay and in a few remote locations in Del Norte County.

Far Northern California may have the worst erosion because it has more rainfall and larger waves, but more surveys will be needed to demonstrate a direct relationship, said Zuzanna M. Swirad, one of the authors.

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Cliffs next to sandy beaches also showed the highest rates of erosion.

"This finding is counter-intuitive, because wide beaches can protect cliffs from wave action. However, waves can also use beach sand as an abrasive to erode the lower cliff," read the study, which was published in the journal Geomorphology.

Using lidar, which takes precise measurements with laser pulses, the study analyzed 538 miles of the 1,023-mile California coast - which includes the majority of its cliffs - and found erosion on half of them. It measured both clifftops, otherwise known as the cliff edge, and the cliff faces beneath them to get the fullest picture of erosion. The results of the study, which was funded by the California Ocean Protection Council and California Department of Parks and Recreation and is based partly on previous research funded by California Sea Grant, are presented in an interactive map.

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On average, the coast lost about 2 inches annually between 2009-2011 and 2016, according to the findings by Swirad and her fellow researcher, Adam Young. However, that average includes cliff failures as large as 16 feet per year in places like Martin's Beach in San Mateo County and Big Sur.

Other areas found to have high rates of clifftop erosion in the Bay Area include El Granada, which is north of Half Moon Bay in San Mateo County, and a few stretches of Point Reyes National Seashore. But the study didn't tease out all the reasons behind the cliffs' retreat.

"We still need to find direct relationships between erosion and driving forces (waves, rain, rock hardness) to better predict where erosion will happen under (a) changing climate," Swirad, who is now at the Polish Academy of Sciences in Warsaw, said by email.

The researchers say it is the first study to use high-resolution data to analyze cliff erosion all along the coast.

Sea level rise and more extreme storms that result from human-caused climate change are expected to increase coastal erosion over time. The state's coastal region represents a $45 billion tourism and recreation economy and is also key to transportation and infrastructure, according to the California Coastal Commission, which recommended long-term planning to address the threats of sea level rise in a report last year.

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The time period the study looked at - when the relatively new lidar technology became available - may not be representative of the overall picture of erosion on the coast, said Gary Griggs, professor of earth sciences at UC Santa Cruz, who was not involved in the study.

Ocean and weather conditions that cause erosion vary during La Niña or El Niño weather events and longer-term climate patterns called the Pacific Decadal Oscillation.

"One of the things we do know about coastal cliff erosion is it's very episodic," said Griggs, who tends to rely on less high-tech aerial photos that go back to the 1920s when measuring erosion. "It turns out the period they looked at from 2009 to 2014 was a calmer, cooler period with with less dramatic wave action and erosion," he said, though he said storm action did pick up from 2014 to 2016.

Tara Duggan is a San Francisco Chronicle staff writer. Email: tduggan@sfchronicle.com Twitter: @taraduggan

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california department of parks and recreation

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California's cliffs are crumbling into the sea. This map shows the spots where they're eroding the fastest

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Counties in California's far north are seeing coastal cliffs erode faster than elsewhere in the state, according to a new study.

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Erosion Impacts the Pacific Coast Highway

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Erosion Impacts the Pacific Coast Highway

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Erosion impacts the Pacific Coast Highway in Ventura County, California | Latest Weather Clips | FOX Weather

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Caltrans is working to repair the Pacific Coast Highway from recent atmospheric river events.

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With its miles of white sand cerulean water, California is synonymous with its beaches. A world-famous tourist destination, the coast of the Sunshine State is home to some of the most high-dollar residential properties in the world. Sunbathers, beachcombers, and surfers flock to the coast for nearly year-round sunshine and consistently warm weather. Despite its famously steep cost of living, California hosts the highest coastal population in the continental U.S.

Aside from its beauty, the Golden Coast serves a critically important purpose: it is the first line of defense against storm impacts for millions of residents. As rising sea levels encroach on California's beaches, homes and businesses are left vulnerable to flooding and foundational damage.

Erosion on the California Coast

Presently, about 85% of the California coast experiences active erosion. As water levels rise and sand is depleted, miles of recreational beaches and nature preserves will become submerged. According to the U.S. Geological Survey, up to 67% of Southern CA beaches could become completely eroded by 2100. If California's vanishing beaches are not addressed, erosion could eventually claim thousands of oceanfront structures.

Damage to native marine ecosystems aggravates accelerated coastal erosion. Watersports and recreational boating can damage reefs, create wakes, and disrupt tidal patterns. Marine vegetation beds, oyster reefs, marshes, and wetlands are natural structures that soak up tidal surges, absorb wave energy, and anchor sand. Human activities that harm these features unbalance native ecosystems and accelerate erosion. Living shorelines address the problem of disappearing beaches by restoring the ecosystems that nourish them naturally.

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Coastal Erosion & Beach Erosion Project Resources · Coastal Restoration

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Our coastlines are home to over 40% of the US population. Keeping coastal estuaries and shorelines natural increases the resilience to erosion. See how...

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The U.S. Geological Survey's Volcanoes and Current Activity Alerts map shows the location and activity levels of all volcanoes in the United States. The map allows for filtering based on both location and current volcano status. Each volcano is depicted by a small colored triangle with different colors indicating various volcano alert levels:

Users can click on individual volcanoes to see that volcano's page on the USGS website.

Click here to use the Volcanoes and Current Alerts map

Source: U.S. Geological Survey Volcano Hazards Program

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Interactive map of volcanoes and current volcanic activity alerts in the United States

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The U.S. Geological Survey's Volcanoes and Current Activity Alerts map shows the location and activity levels of all volcanoes in the United States. The map allows for filtering based on both location and current volcano status.

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Photo USGS Mt. St. Helens, Washington
Cascade Range Volcanoes and Volcanics - Current Updates
"More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the last 10,000 years. ... Sooner or later, volcanoes in California will erupt again, and they could have serious impacts on the health and safety of the State's citizens as well as on its economy." Miller, C. Dan (USGS)

"California is the most geologically diverse state in the nation. We are known for our earthquakes, landslides and flood hazards. But our nearly forgotten hazard is our volcanoes," said Dr. John Parrish, the State Geologist of California. (USGS)

USGS Photograph taken by Lyn Topinka, 1984
Mt Shasta Cam
Mount Shasta
Elevation: 14,162 feet
Location: Northern
California, USA

May 22, 1915 eruption -Photo: R.E.Stinson
Mount St. Helen's Cam
Mount St. Helen's
Elevation: 4,500 feet
Location: Washington State/Johnston Ridge Observatory

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Attribution: Natural Hazards, Volcano Hazards Program Office, Region 9: Columbia-Pacific Northwest, Region 10: California-Great Basin, Region 11: Alaska, Region 12: Pacific Islands (American Samoa, Hawaii, Guam, Commonwealth of the Northern Mariana Islands), Volcano Science Center, California Volcano Observatory, Cascades Volcano Observatory, Hawaiian Volcano Observatory, Yellowstone Volcano Observatory

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To restore, protect and manage the state's natural, historical and cultural resources for current and future generations using creative approaches and solutions based on science, collaboration and respect for all the communities and interests involved.

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This is a map showing where the San Andreas Fault runs through California.

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California Department of Conservation administers a variety of programs vital to California’s public safety, environment and economy. The services DOC provides are designed to balance today’s needs with tomorrow’s obligations by fostering the wise use and conservation of energy, land and mineral resources.

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As the climate changes and forest fuel loads aren’t properly managed, California’s wildfire season is changing. See how it has shifted over time in this interactive map.