Department of Earth Science |Northeastern Illinois University

INTRODUCTION TO EARTH SCIENCE
ESCI 121
Section 06
Fall 2009

Daily Objectives #18  (November 3, 2009)                                                                                                         Dr. Sanders

The homework assignment on Earthquake Maps is due today!

A new homework assignment (Weather Tracking) has been posted on the Homework page.

An extra credit opportunity has been posted on the Homework page. 

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

EARTHQUAKES

w  Explain the difference between the focus of an earthquake, and the epicenter. 

w  Tell what the term magnitude means as applied to earthquakes.

w Explain how a seismometer works.

w Explain why every seismograph includes at least three seismometers.

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

w 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.

w After viewing some of the videos and animations of the Indian Ocean tsunami of December 26, 2004, research 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  Using the earthquake maps the class produced, arrange them in meaningful groups based on the patterns of earthquake epicenters and based on the patterns of focal depths you observe in each.  Groups for this activity: