Department of Earth Science |Northeastern Illinois University

ESCI 121
Spring 2007

Daily Objectives #14
(March 7, 2007)                                                                        Dr. Sanders

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

* Sketch a diagram illustrating the meaning of the terms epicenter and focus (also called hypocenter) as they apply to earthquakes.

* Describe P-waves and S-waves: their motion, velocity, arrival times, and ability to travel through liquids.

* Explain why P- and S-waves reach seismometers at different times, and tell how the time difference helps us learn how far away an earthquake occurred.

* Tell why it is necessary to have seismograms for an earthquake from at least three different locations before we can locate an earthquake epicenter.

* Examining seismograms from three monitoring stations for the December 26, 2004 Indonesian earthquake, for each monitoring station, calculate the P-S time difference, find the distance of the epicenter from the station, and plot the distances on a map to locate the epicenter.

* Explain what is expected of you in Homework #4, due on Monday. 

Department of Earth Science | Northeastern Illinois University

© 2007 Laura L. Sanders.  Last updated March 7, 2007.