Earthquakes
Earthquakes may be more common than you think! The United States Geological Survey estimates that there are close to a half a million detectable earthquakes per year. While people feel approximately 100,000 of those, only approximately 100 cause damage. Historical records predict about 16 significant, those greater than a magnitude 6, earthquakes worldwide in any given year. It can be terrifying when the earth shakes, and earthquakes have caused massive damage and many injuries and deaths. Anyone who has lived through a strong earthquake cannot forget the experience. But geoscientists and engineers are getting better at understanding earthquakes, minimizing the amount of damage they cause, and reducing the number of people affected. In the time lapse video (Figure 5.0.1), you can see historical earthquakes that have occurred in Arizona.
Video 5.1 Time lapse video of historical earthquakes in AZ from 1852 to 2011 (1:28). CC-BY
Learning Objectives
After carefully reading this chapter, you should be able to:
- Explain how the principle of elastic deformation applies to earthquakes.
- Describe how the main shock and the immediate aftershocks define the rupture surface of an earthquake, and explain how stress transfer is related to aftershocks.
- Describe the relationship between earthquakes and plate tectonics, including earthquakes location at different types of plate boundaries and their depths.
- Distinguish between earthquake magnitude and intensity, and explain some ways to estimate the magnitude.
- Describe how earthquakes can cause the destruction of buildings and other infrastructure, fires, slope failures, liquefaction, and tsunami.
- Discuss the value of earthquake forecasting, and describe some steps that governments and individuals can take to minimize the impacts of large earthquakes.
- Describe earthquakes in Arizona.
