Examine the image above. What do you see? Is this an example of what pollution can do over time? Write a paragraph about what you see in the picture. Later in this section, you will watch a tutorial that will answer the questions.

The movement and collision of crustal plates is the way that most of the islands of the Pacific have been formed over time. For example, throughout the Pacific, one can find many examples of island arcs. An island arc is a type of archipelago formed by plate tectonics. One plate goes under another plate and produces magma. The Philippines, Mariana Islands, and Tonga are a few examples of island arcs.

The Ring of Fire has 452 volcanoes (approximately 75% of the world’s volcanoes) and is home to more than 90% of the world’s earthquakes. Many of these earthquakes occur underwater and are barely felt by any people. The volcanoes of Indonesia are formed due to subduction zones between the Eurasian Plate and the Indo-Australian Plate. A subduction zone is an area where two plates move toward each other and one moves under the other. Some volcanoes have erupted more than others. For example, Mount Canlaon, located in the Philippines, is the most active volcano in the region and has erupted 25 times since 1866. However, the volcanoes found in Indonesia are the most active of the region. The region is accustomed to severe earthquakes and volcanoes, but they are not always well prepared. In recent years, greater effort has been made to create early warning systems for the citizens to mitigate damage from large earthquakes and volcanoes. In 1991, scientists correctly predicted the onset of one of the largest eruptions of the 20^th century at Mount Pinatubo. Due to this early warning, tens of thousands of people were evacuated and their lives were saved.

There are many oceanic trenches in this region. A trench is a long, but narrow, topographic depression on the bottom of the sea. Oceanic trenches generally extend 1.9 to 2.5 miles below the level of the surrounding oceanic floor. The deepest known trench is the Mariana Trench.

This disaster is often called The Boxing Day Tsunami due to the fact that it falls on the European holiday called Boxing Day – the day after Christmas. This tsunami is the deadliest tsunami in recorded history - killing more than 225,000 people in eleven countries! Scientists have estimated that the earthquake that generated the great Indian Ocean tsunami of 2004 is estimated to have released the energy of 23000 Hiroshima-type atomic bombs.

Although some of the tsunami waves took anywhere from 15 minutes to 7 hours to reach various coastlines, most citizens were clearly not prepared because there was no tsunami warning system in place in the Indian Ocean. Additionally, due to the relative poverty of the region, there was no good way to warn the citizens.

As well as the sideways movement between the plates, the sea bed is estimated to have risen by several meters, displacing an estimated 7 cubic miles of water and triggering devastating tsunami waves. Humans played a large role in the devastation caused by the tsunami waves – destroying the coral reefs, eliminating coastal mangrove trees, and eliminating coastal sand dunes are all a cause for increased devastation and destruction. According to specialists, the greatest long-term environmental impact from the tsunami is due to the infiltration of the freshwater supplies and arable farmland by the sea water – poisoning the water and land with large amounts of salt.

Following the great Sumatra-Andaman earthquake, many aftershocks and triggered earthquakes were felt throughout the region. A "triggered earthquake" typically differs from an aftershock in that it is not located along the same fault line and may be as large, or larger, than the earthquake which triggered it.