My web page was created to fulfill an assignment in Introduction to Earth Science Lab class at Emporia State University. The topic I chose is earthquakes. In our earthquake lab, I learned how to identify exactly where P-waves and S-waves, primary and secondary waves, occurred during an earthquake. The P-waves compress, causing the particles in the material to vibrate back and forth in the same direction as the waves move. The S-waves cause particles to oscillate at right angles to the direction of wave motion. I also learned how to locate the epicenter of an earthquake by using a time-travel graph, and triangulation from three earthquake recording stations.

These images were taken from USGS.

An earthquake is caused by friction under the earth’s crust. The point at which the earthquake occurs under the surface is called the focus. The point on the earth's surface at which the earthquake occurs is the epicenter. Earthquakes commonly occur on fault lines. When plate tectonic boundaries slip past each other, they release tension, and this movement can cause the earth to shake, thus producing what we know as an earthquake.

Perhaps one of the most common mysteries about earthquakes is how exactly are earthquakes measured? There are two scales which earthquakes can be measured by. One type of scale is called the Richter Scale. "The Richter Scale was developed by Charles F. Richter in 1935. It is a logarithmic measurement of the amount of energy released by an earthquake" (FEMA). The second type of scale is called the Mercalli Intensity scale. "The intensity of a quake is evaluated according to the observed severity of the quake at specific locations. The Mercalli scale rates the intensity on a Roman numeral scale that ranges from I to XII" (FEMA).

Tarbuck, E.J., Lutgens, F.K.  Earth Science (9th ed.). Upper Saddle River, N.J., 1997.

Aber, Susan W., Johnston, P., Hengchun, Y.  Introduction to Earth Science Lab (4th ed.).  Burgess International Group, Edina, MN, 1996.

FEMA, at http://www.fema.gov/fema/fact01e.html.

USGS, Finding an earthquake's location with modern seismic networks.

For additional information on earthquakes, visit these external links: