Chapter 6 by cowcowfun

Tsunami

john_amabile — 2015-03-02 16:34:25 UTC

Earthquakes can cause tsunamis. These deadly ocean waves may result from any shock to ocean water. A shock

could be a meteorite impact, landslide, or a nuclear explosion. But most come from large underwater earthquakes.

An underwater earthquake creates a tsunami this way: the movement of the crust displaces water. The displacement

forms a set of waves. The waves travel at jet speed through the ocean. Since the waves have low amplitudes and

long wavelengths, they are unnoticed in deep water. As the waves reach shore they compress. They are also pushed

upward by the shore. For these reasons, tsunamis can grow to enormous wave heights. Tsunami waves can cause

tremendous destruction and loss of life. Fortunately, few undersea earthquakes generate tsunamis

The Boxing Day Tsunami

john_amabile — 2015-03-02 16:36:09 UTC

2004The Boxing Day Tsunami struck on December 26, 2004. The tsunami was caused by one of the largest earthquakesever recorded. The Indian Ocean Earthquake registered magnitude 9.1. The quake struck near Sumatra, Indonesia,where the Indian plate is subducting beneath the Burma plate. It released about 550 million times the energy of theatomic bomb dropped on Hiroshima.286

Seismometers

john_amabile — 2015-03-02 16:38:16 UTC

A seismograph is a machine that records seismic waves. In the past, seismographs produced a seismogram. Aseismogram is a paper record of the seismic waves the seismograph received. Seismographs have a weightedpen suspended from a stationary frame. A drum of paper is attached to the ground. As the ground shakes in anearthquake, the pen remains stationary but the drum moves beneath it. This creates the squiggly lines that make upa seismogram

What We Learn from Seismograms

john_amabile — 2015-03-02 16:39:03 UTC

Seismograms contain a lot of information about an earthquake: its strength, length, and distance. Wave height isused to determine the magnitude of the earthquake. The seismogram shows the different arrival times of the seismicwaves. The first waves are P-waves since they are the fastest. S-waves come in next and are usuallylarger than P-waves. The surface waves arrive just after the S-waves. If the earthquake has a shallow focus, thesurface waves are the largest ones recorded.FIGURE

Summary

john_amabile — 2015-03-02 16:51:15 UTC

After reading 6.10 and 6.11 I thought of some things

• A seismograph records seismic waves on a seismogram. A seismometer is a digital seismic wave recorder.

• S-waves do not travel through liquids. So a seismogram with no S-waves is on the other side of the planet

from the quake.

• Seismographs yield a tremendous amount of information about an earthquake.

• A New Project to Measure Earthquakes at

1. What was the largest earthquake in history?

2. What is Earthscope doing?

3. How many instruments are being installed with this project? In what region?

4. How far apart are the seismometers being distributed?

5. What do researchers hope to do with the data?

Marie Tharp

john_amabile — 2015-03-16 15:14:13 UTC

She gave a map of the seafloor making everyones life easier