Why learn about earthquakes and earthquake safety? Earthquakes are caused when accumulated stress causes sudden slips along fault lines in the earth’s crust. Even though earthquakes are most likely to happen in certain regions of the world where fault lines lie, earthquakes can strike any place at any time. In the United States, earthquakes pose a significant risk to about 75 million people in 39 states, according to the U.S. Geological Survey. Thus, it’s worth learning about earthquakes, including where they are most likely to occur, and how to react when an earthquake occurs.


1. The magnitude of earthquakes is determined by ________________________.


2. Scientists have been measuring earthquakes for about ______ years.


3. True or False? California has the most earthquakes in the United States.


4. True or False? People can cause earthquakes.


5. True or False? During an earthquake, the safest places in buildings are doorways.