Download Lecture 5: Earthquakes I. What are earthquakes? II. The elastic

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Lecture 5: Earthquakes
I. What are earthquakes?
II. The elastic rebound theory
III. Seismology: The Study of Earthquakes
A. Seismographs
B. How do seismographs work?
IV. Seismic waves
A. Definition
B. Modes of vibration
1. Surface waves
2. Body waves
3. Types of body waves
a. Primary or P waves
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b. Secondary or S waves
C. Records of Seismic Waves
V. Locating the Source of an Earthquake
A. Focus
B. Epicenter
C. Determining the distance to earthquake
1. Difference in Velocities of S & P waves:
2. Travel time graphs
3. Using travel time graphs
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First S wave
Time (min)
15
5 minutes
10
First P wave
5
0 0
1000
Distance
2000
3000
2
D. Finding the location of the earthquake: Triangulation
VI Earthquake belts
VII. Earthquake intensity and magnitude
A. Intensity: Mercalli Scale
B. Magnitude: The Richter Scale
C. Moment magnitude
VII Prediction and Minimizing Risks
1. Clear coincidence of earthquakes with plate boundaries
2. Depth of earthquake related to type of boundary
3. Forecasts based on history and movement along faults
4. Importance of local geology