EARTHQUAKE MEASUREMENT 10/23/14

8-2 pgs. 202-204

IN: Which plate boundaries have the strongest earthquakes?

LOCATING EARTHQUAKES

Seismographs – instruments located at or near the surface of the Earth that record seismic waves.

Seismogram – a tracing of earthquake motion created by a seismograph.

WHEN DID IT HAPPEN?Scientists compare the arrival times of P waves and S waves.

Remember P-waves travel faster than S-waves.

http://www.sciencecourseware.com/eec/Earthquake/EpicenterMagnitude/Tutorials/SP.swf

WHERE INSIDE EARTH DID IT HAPPEN?

Focus - is the point inside Earth where an earthquake begins.

WHERE ON THE SURFACE DID IT HAPPEN?Epicenter - is the point on the Earth’s surface directly above the earthquake’s starting point (focus).

HOW DO WE FIND THE EPICENTER?Use three seismographs.

MEASURING EARTHQUAKESThe Richter scale is used to measure earthquakes.

Richter magnitude scale - Wikipedia, the free encyclopedia

OUT: What is the difference between a seismogram and a seismograph?