Earthquakes. Copyright 2006 InstructorWeb

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1 Earthquakes Earthquakes cause the earth to shake! Earthquakes are caused by a fault line under the earth's crust. You do not have to be right under a fault line to feel an earthquake. You could be miles away and still feel the rattling of the earth! Most earthquakes only last for about one minute. They cannot be predicted before they happen. You can always tell an earthquake is coming because the ground will begin to shake. You might see things fall off your shelves. Your door may rattle and shake! If it is a strong earthquake, you might hear low rumbling noises. You will feel strong jerks as the earth moves unexpectedly. Scientists use something called a Richter scale to figure out how bad an earthquake really is. Earthquakes below 2.0 are secret earthquakes. The reason they are secret is most people cannot feel them. Earthquakes that are below 4.0 on the scale are small earthquakes. These earthquakes do not normally cause any damage. If the scale hits 5.0 then there could be damage. At 6.0, the earthquake is becoming very dangerous. It is considered "strong". If the earthquake reaches 7.0 it is a full blown, major earthquake. The most important thing to remember during an earthquake is to drop, cover, and hold on. If there are only three things, you remember it should be those. Drop to the floor or ground, find something to cover you with, and hold on until the shaking is over. One of the largest earthquakes in recent years was the Northridge Earthquake. This earthquake happened in The earthquake measured 6.7, which made it a very dangerous earthquake! Over 2,000 square miles were hit by this one earthquake. Fifteen thousand aftershocks happened after the main quake occurred. An aftershock happens when the earth shakes due to settling after a large earthquake. The Northridge Earthquake was the biggest earthquake in Southern California since It was also the 11th biggest earthquake since The reason earthquakes are so dangerous is simple: there is no pattern. Earthquakes can happen at any time, day or night. Unlike a tornado, you cannot guess when one will occur, based on weather. There is no such thing as earthquake weather. Earthquakes occur because fault lines rub together. This happens way below the earth s surface. In the United States, California has more earthquakes than any other state. This is because there are many different fault lines running underneath the state. Some states have fault lines but hardly ever have earthquakes. Two states, that do not have earthquakes very often despite being above a fault line, are Michigan and New York. There have been many earthquakes in California but not all of them are huge! Luckily, big earthquakes do not happen as often as smaller ones. However, that does not mean they could not happen. Some of the largest California earthquakes include: 1

2 January 17th, This is one of the most destructive earthquakes from California in recent years. This earthquake caused $15 Billion in damages, 9,000 injuries, and 57 deaths. October 17th, This earthquake lasted only 15 seconds. It caused $6 billion in damage. Over 3,000 injuries were reported. Sixty-two people lost their lives. May 2nd, This earthquake caused a lot of property damage. Unlike many other earthquakes, no one died. However, there were 47 injuries. April 18th, This earthquake was not only the strongest in U.S. history but it created mass destruction and fires. It only lasted 40 seconds but as many as 2,500 people lost their lives. While you cannot stop earthquakes from happening, you can do things to protect your property and home during small earthquakes. China Cabinets and shelves should be attached to wall studs Hanging Plants should be in light pots that are unbreakable Mirrors should be fastened to the wall to ensure they will not come down Any heavy objects on a shelf should be towards the bottom of the shelf Beds should not be near windows Nothing should be over a bed on the wall. No pictures or mirrors should be above the bed Cabinet doors should have latches on them to keep them closed All plumbing should be attached to the wall to keep things secure The house should be bolted to the foundation 2

3 Richter Scale Chart The Richter Scale Level Level of Damage Type of Damage 4.3 or less No Damage Often cannot be felt Small amounts of Glasses might break damage Strong amounts of damage Furniture could move and walls could crack Damage to homes is possible Furniture will break and bricks and other Damage is going to happen for sure structures could fall Trees will be damaged, homes knocked down, cracks in the ground Severe damage Larger cracks in the ground and homes and businesses will collapse Full blown disaster Well built homes will be destroyed and damage will occur to dams and embankments Very Dangerous Very few structures will remain standing. Bridges will be destroyed 8.1 and higher Complete damage Everything in the immediate area will be completely destroyed 3

4 Earthquakes Worksheet 1. Why do earthquakes happen? A. Fault lines under the earth B. Weather patterns C. Bad luck D. No one knows 2. How do people know there is an earthquake coming? A. It will be raining B. They can just tell C. The ground will begin to shake D. None of the above 3. What is the name of the scale used to measure earthquake levels? A. Richmond B. Richland C. Rickman D. Richter Matching Match the number of the Richter scale with the amount of damage it could cause A. Damage will happen for sure B. Small amounts of damage C. No damage D. Full blown disaster E. Very dangerous F. Complete damage G. Strong amounts of damage H. Damage to homes is possible I. Severe damage 4

5 True or False 13. The strongest earthquake in North America occurred on January 17, California has more earthquakes than any other state. 15. Earthquakes can happen at anytime of day and in any type of weather. 5

6 Answer Key 1. A 2. C 3. D 4. C 5. B 6. G 7. H 8. A 9. I 10. D 11. E 12. F 13. False 14. True 15. True 6