湖北自考网2016-04-06 10:05:28
Predicting Earthquakes

Can earthquakes be predicted? Scientists are working on programs to predict where and when an earthquake will occur. They hope to develop an early warning system that can be used to forecast earthquakes so that lives can be saved.

Earthquakes are the most dangerous and deadly or all natural events. They occur in many parts of the world. Giant earthquakes have been recorded in Iran, China, Guatemala, Chile, India, and Alaska. Two of the biggest earthquakes that were ever recorded took place in China and Alaska. These earthquakes measured about 8.5 on the Richter Scale. 

The Richter Scale was devised by Charles Richter in 1935, and compares the energy level of earthquakes. An earthquake that measures a 2 on the scale can be felt but causes little damage. One that measures 4.5 on the scale can cause slight damage, and an earthquake that has a reading of over 7 can cause major damage. It is important to note that a reading of 4 indicates an earthquake ten times as strong as one with a reading of 3. Scientists want to be able to predict those earthquakes that have a reading of over 4 on the Richter Scale.

How do earthquakes occur? Earthquakes are caused by the shifting of rocks along cracks, or faults, in the earth's crust. The fault is produced when rocks near each other are pulled in different directions. The best-known fault in North America is the San Andreas fault in the state of California in the United States.

The nations that are actively involved in earthquake prediction programs include Japan, China, Russia, and the United States. These countries have set up seismic networks in areas of their countries where earthquakes are known to occur. These networks are on the alert for warning signs that show the weakening of rock layers that can precede an earthquake. Many kinds of seismic instruments are used by the networks to monitor the movements of the earth's crust. The scientists also check water in deep wells. They watch for changes in the water level and temperature that are associated with movement along faults.

Scientists in China, Russia, and the United States measure radon in ground water. Radon is a gas that comes from the radioactive decay of radium in rocks. The gas flows through the ground and dissolves in underground streams and wells. Scientists speculate that the amount of radon increases in the ground when rocks layers shift, exposing new rock, and thus more radon.Chinese and Russian scientists have reported that in places where stress is building up, the radon levels of the water build up too. When the radon levels of the water subside and drop back to normal readings, an earthquake may occur. United States scientists have also placed radon monitoring stations in earthquake zones, particularly California. However, all the scientists agree that more data is necessary to prove that radon levels in water are associated with the possible birth of an earthquake.

Earthquake prediction is still a young science. Everyone agrees that earthquakes cannot be predicted with any reliability. Scientists have only a partial understanding of the physical processes that cause earthquakes. Much more research has to be done. New and more up to-date methods have to be found for collecting earthquake data and analyzing it. However, scientists have had some success in predicting earthquakes. Several small earthquakes were predicted in New York State, in the eastern part of the United States. Chinese scientists predicted a major one in Haicheng in 1975, and Russian scientists predicted a major one in Garm in 1978. While this is a small start, it is still a beginning.



地震是自然灾害中最危险的最致命的,发生在世界许多地方。伊朗、中国、危地马拉、智利、印度和阿拉斯加都有过大地震的记录。有记载的最大两次地震是发生在中国和阿拉斯加。这两次地震经测量约为里氏8.5级。里氏震级是1935年查尔斯里克特发明的,用来比较地震的能量等级。里氏地震级测出的2 级地震可以感觉到,但几乎没什么破坏;测出的4.5级地震能够造成轻微破坏,读数超过7级的地震会带来重大破坏。必须注意的是,读数为4级的地震表明其强度是读数为3级的10倍。科学家想预测那些读数超过里氏4级的地震。



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