GLG 101
Week #3 White Paper: Earthquakes


Living in Southern California and near a major earthquake fault I have wondered why the Earth shakes and why the Earth only shakes in certain parts of the United States. In searching for the information to complete my paper, I was also able to find the answers to my own personal questions. This paper will answer these questions: how does the Earth move and when, what events cause the Earth to shake, how are earthquakes measured and what are the two types of body waves and earthquake creates.

Causes of Earthquakes
An earthquake is caused when there is an unexpected and sudden release of energy within the Earth’s crust, creating seismic waves. A break in geological faults beneath the Earth’s surface can also cause earthquakes. However, earthquakes can also be due to volcanic activity, nuclear experiments and landslides. A naturally occurring earthquake will happen within the Earth’s surface where there is enough stored energy and heat which will cause plates to move. So why does the Earth move when these plates move?
The Earth moves because when the two plates or faults move they sometimes get stuck together as they shift. The built up energy that moves the plates becomes stored and when that energy is finally released it causes the Earth to shake.
Earthquakes are measured with a seismometer, which is also called a seismograph. A seismometer measures and records the motions beneath the Earth’s surface which includes seismic waves cause by earthquakes. A seismometer allows seismologists to create a map of the Earth’s interior. Another instrument used to measure earthquakes is a Richter magnitude scale. This instrument gives a number to the amount of seismic energy released during an earthquake. The Richter magnitude scale was developed in 1935 by Charles Richter.
The intensity of an earthquake is measured using a Mercalli scale. The Mercalli scale determines the effects that the earthquake has on...