Project Java Webmaster: Glenn A. Richard
Mineral Physics Institute
SUNY Stony Brook
This applet illustrates the utilization of the arrival times of P and S waves at seismic stations to determine the location of earthquake epicenters. Since P waves travel through the shallow parts of Earth at about 8 kilometers per second, and S waves travel at about 5 kilometers per second, the P waves will arrive first at a seismic station after a quake occurs. In fact, the delay time between the arrival of the P waves and the arrival of the S waves increases with distance and can be used to compute the distance from the event.
The distance of the epicenter form each station can be repsresented by a circle of appropriate radius. With data from three or more stations, circles can be drawn on a map that intersect at the epicenter.
This version of the Finding Earthquake Epicenters applet challenges you to figure out where the epicenter of an earthquake is located. Click the New Earthquake button to generate a virtual event. The delay times between the arrival of the P and S waves will be shown at each station. You can use this data to compute distances or you can click the Show Distances button to have the applet do the computation and display the results. When you think you have determined location of the epicenter, click the location on the map. The applet will let you know how far off you were. You can guess as many times as you want. In order to reveal the location of the epicenter, click the Show Epicenter button. The Hide Details button removes the arcs and/or distances from the screen. You can change the scale of the map by entering a number in the Scale field.
Source List for the Three Versions of Quake
Yevgevniy Miretskiy: eugene@invision.net
Mikhail Sabaev: sabaevm@ug.cs.sunysb.edu