1. Earthquakes

2. What are Earthquakes? Earthquakes are vibrations caused by Earth movements at plate boundaries and at major fault lines (cracks in the earth’s surface).

3. How do earthquakes happen? Two plates at a plate boundary cannot move past each other easily.

4. Where do earthquakes occur? The majority of the earthquakes and volcanic eruptions occur along plate boundaries such as the boundary between the Pacific Plate and the North American Plate. One of the most active plate boundaries where earthquakes and eruptions are frequent is around the massive Pacific Plate commonly referred to as the Pacific Ring of Fire.

5. How can we measure earthquakes? The Richter Scale This measures the magnitude of a tremor (how powerful it is) using an instrument called a seismograph.

6. What are some ways to predict earthquakes? Water levels can rise in wells and lakes because of cracks in the rock A tiltmeter can check any movement within the rocks Forshocks before the main quake can be detected by a seisometer Animals can act strangely before the earthquake

7. Emergency Response Plan If you live in an earthquake zone you should have a safe spot in every room. You should take a first aid class and practice a maneuver to keep you safe. You should have extra supplies to last at least three days.

8. Earthquake Facts The largest recorded earthquake in the U.S. was a magnitude 9.2 that struck Prince William Sound, Alaska on March 28, 1964. The earliest reported earthquake in California was felt in 1769 by an exploring expedition while camping 30 miles southeast of Las Angeles. It is estimated that there are 500,000 detectable earthquakes in the world each year. 100,000 of those can be felt, and 100 of them cause damage.

9. Earthquake Facts Continued Each year the southern California area has about 10,000 earthquakes. Most of them are so small that they are not felt. If there is a large earthquake, the aftershock sequence will produce many more earthquakes of all magnitudes for many months. Florida and North Dakota have the smallest number of earthquakes in the United States.