By the end of today's class, you should be able to do the following:

MEASURING EARTHQUAKES

w Review: Describe P-waves and S-waves and explain the differences between them.

w Review: Demonstrate how to use a seismic P-S lag (time difference) to determine the distance to an earthquake epicenter.

w Show how to locate the epicenter of an earthquake using seismograms from three different stations.  Explain why it is necessary to use data from at least three stations.  (You will need: map, compass, graph of P- and S-wave travel times, three seismograms for the event).

w After viewing some of the videos and animations of the Indian Ocean tsunami of December 26, 2004, analyze the seismograms from the event.

w Use seismograms to find the epicenter of an earthquake using the Indian Ocean tsunami as an example.  (Extra copies of the map, the seismograms , and the P-S lag (time difference) graph are linked to this page.  This exercise is abridged from an exercise copyrighted in 2004 by Dave Robison and Steve Kluge.)

w Use the results of your calculations to determine exactly when the earthquake occurred.

w Assuming that the Dec. 26, 2004 tsunami traveled at 600 km/hour (an average speed for tsunamis in the open ocean), estimate how long it would take to arrive at Indonesia, Sri Lanka, India, and Somalia.