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Earthquakes are the shaking, rolling or sudden shock of
the earth’s surface. Earthquakes happen along "fault lines" in the earth’s
crust. Earthquakes can be felt over large areas although they usually last
less than a minute. Earthquakes cannot be predicted - although scientists
are working on it!
Most of the time you will notice an earthquake by the gentle shaking
of the ground. You may notice hanging plants swaying or objects wobbling
on shelves. Sometimes you may hear a low rumbling noise or feel a sharp
jolt. A survivor of the 1906 earthquake in San Francisco said the sensation
was like riding a bicycle down a long flight of stairs.
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On the Richter scale:
Between 4.3-4.8 Between 4.8-6.2 Between 6.2-7.3 Between 7.3-8.9 |
The intensity of an earthquake can be measured. One measurement used is called the Richter scale. Earthquakes below 4.0 on the Richter scale usually do not cause damage, and earthquakes below 2.0 usually can’t be felt. Earthquakes over 5.0 on the scale can cause damage. A magnitude 6.0 earthquake is considered strong and a magnitude 7.0 is a major earthquake. The Northridge Earthquake, which hit Southern California in 1994, was magnitude 6.7. |
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Fault Lines - Breaks in the Earth's crust where pressure is sometimes released, like in an earthquake. Richter Scale - The scale used by scientists to measure the intensity of an earthquake. It was created by Charles F. Richter in 1935. Aftershocks - Follow-up earthquakes that occur after and are
usually smaller than the first one.
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The most important thing to remember during an earthquake is to DROP and COVER. Drop and cover means to DROP to the floor and get under something for COVER. If you are indoors during an earthquake, stay calm and take cover under a heavy table or desk. Stay away from glass, windows or anything that could fall, like a bookcase. If you are outdoors, move away from buildings, street lights and utility wires. If you are in a crowded public place, do NOT rush for the doors. Everyone will be doing that. Instead, take cover under something heavy and stay away from things that could fall on you. Stay calm. Do not get in an elevator during an earthquake! After an earthquake, be prepared for aftershocks. Aftershocks are follow-up earthquakes that are usually smaller than the first one. They are dangerous because they can cause things that are weakened in the first earthquake to fall down. If you are home and you smell gas or hear a hissing or blowing sound, open a window and get out of the building right away. It may mean that a gas line in your house has been broken. Tell your parent or another adult. Make sure you are wearing shoes after an earthquake. There may be broken
glass on the ground and inside your home.
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