预测地震

What if you could predict an earthquake?
::如果你能预测到地震怎么办?

What would make a good prediction? Knowing where, when, and the magnitude of the quake would make it possible for people to evacuate. If you were right, you would be famous! But if you were wrong, many people would be angry with you.
::怎样才能预测好呢?你知道地震何时何地、何地、何地、何地、何地大地震使人们得以撤离。如果你是对的,你就会出名。如果你错了,许多人就会生你的气。

Earthquake Prediction
::地震预测

Scientists are a long way from being able to predict  . A good prediction must be detailed and accurate. Where will the earthquake occur? When will it occur? What will be its approximate magnitude? With a good prediction, authorities could get people to evacuate. But if the prediction were wrong, a lot of money would be lost as people closed businesses and skipped work. Plus people would be unlikely to believe the authorities the next time.
::科学家们远不能预测。好的预测必须是详细和准确的。地震会在哪里发生?地震会在哪里发生?地震会在哪里发生?它的大致规模会在哪里?如果是良好的预测,当局可以让人们撤离。但如果预测是错误的,那么随着人们关闭企业和跳出工作,就会损失大量金钱。此外,人们下次也不会相信当局。

Predicting Where
::预测地点

Where an earthquake will occur is the easiest feature to predict. How would you predict this? Scientists know that earthquakes take place at  plate boundaries . They tend to happen where they’ve happened before ( Figure   ).
::地震发生地点是最容易预测的特征。 您如何预测呢? 科学家们知道地震发生在板块边界上。 地震发生地点往往发生在以前发生的地方( 图 ) 。

 segments behave consistently. A segment with frequent small earthquakes will likely continue to have frequent small earthquakes. A fault segment with infrequent huge earthquakes will likely have infrequent huge earthquakes. The image below shows the probabilities of earthquakes striking along various faults in the San Francisco area ( Figure   ). The time frame is between 2003 (when the work was done) and 2032.
::经常发生小地震的一段段段会继续频繁发生小地震。不经常发生大地震的断层段可能会不经常发生大地震。下图显示圣弗朗西斯科地区(图 ) 各种断层发生地震的概率。 时间框架是2003年( 工程完成时 ) 至 2032年( 2032年 ) 。

Predicting When
::预测时间

When an earthquake will occur is much more difficult to predict.  Stress  on a fault builds up at the same rate over time. So earthquakes should occur at regular intervals. But, so far, scientists cannot predict when quakes will occur even to within a few years. Around Parkfield, California, an earthquake of magnitude 6.0 or higher occurs about every 22 years. So seismologists predicted that one would strike in 1993. But that quake came in 2004—11 years late ( Figure   ).
::当地震发生时,更难预测。对断层的压力在时间上以同样的速度累积。因此地震应该定期发生。但到目前为止,科学家无法预测地震何时会发生,甚至将在几年之内发生。在加利福尼亚州帕克菲尔德(Parkfield)附近,每22年发生6.0级或更高级的地震。地震学家预测1993年将发生地震,但地震是在2004-11年后发生的(图表 ) 。

Earthquake Signs
::地震标志

There are sometimes signs that a large earthquake is coming. There may be small quakes, called  foreshocks . These can occur a few seconds to a few weeks before a major quake. Unfortunately, foreshocks are not very useful for predicting large earthquakes. Many quakes do not have foreshocks. Also, small earthquakes are not necessarily followed by a large earthquake.
::有时有迹象表明大地震即将来临。 可能发生小地震,即所谓的前震。 地震可能发生在大地震之前几秒钟到几个星期。 不幸的是,前震对预测大地震没有多大用处。 许多地震没有前震。 此外,小地震不一定会发生大地震。

There are other possible signs before an earthquake. The ground may tilt. Ground tilting is caused by the buildup of stress in the  . This may happen before a large earthquake, but it doesn't always.  Water  levels in wells may fluctuate. This is because water may move into or out of fractures before an earthquake. This is also an uncertain way to predict an earthquake. The difference in arrival times of P-waves and  S-waves  may decrease just before an earthquake occurs.
::地震前还有其他可能的迹象。 地面可能会倾斜。 地面倾斜是压力增加造成的。 这可能发生在大地震之前, 但并不总是这样。 水井的水位可能会波动。 这是因为地震前水位可能会进出骨折。 这也是预测地震的不确定方式。 地震发生前P波和S波的到达时间差异可能会缩小。

Folklore tells of animals behaving strangely just before an earthquake. Most people tell stories of these behaviors after the earthquake. Chinese scientists have actively studied the behavior of animals before earthquakes to see if there is a connection. So far nothing concrete has come of these studies.
::民俗说,在地震发生之前,动物的行为就很奇怪。 大多数人讲述地震发生后的行为。 中国科学家在地震发生前就积极研究动物的行为,看看是否有关联。 到目前为止,这些研究没有具体结果。

Actions can reduce the damage once an earthquake has started.  Seismometers  can detect P-waves a few seconds before more damaging S-waves and  surface waves  arrive. In this time computers can shut down gas mains and electrical transmission lines. They can initiate protective measures in chemical plants,   plants, mass transit systems, airports, and roadways. Just a few seconds can be tremendously valuable.
::地震发生后, 地震计可以在破坏力更大的S波和地表波到达前几秒钟内探测P波。 此时计算机可以关闭气管和输电线路。 他们可以在化工厂、 工厂、 大众交通系统、 机场和公路上启动防护措施。 只要几秒钟就非常宝贵了。

Summary
::摘要

• A good prediction must indicate when and where an earthquake will take place.
  ::良好的预测必须表明何时何地将发生地震。

• Fault segments behave the same way over time.
  ::断层区段在一段时间内的行为也是一样的。

• Signs that an earthquakes may occur include foreshocks, ground tilting, water levels in wells, and the relative arrival times of P- and S-waves.
  ::地震可能发生的迹象包括前震、地面倾斜、水井的水位以及P-和S-波的相对到达时间。

Review
::回顾

1. Why is it easier to predict where a quake will occur than when?
   ::为什么比起何时预测地震会在哪里发生更容易呢?

1. List some of the signs that may predict earthquakes.
   ::列出一些可能预示地震的迹象。

1. Along which fault in the San Francisco Bay area is a large earthquake most likely to strike?
   ::旧金山湾地区最有可能发生大地震,

1. The map of earthquake probability from the San Francisco Bay Area was made in 2003. How has the probability likely changed since there's been no major earthquake there in more than a decade?
   ::旧金山湾地区地震概率图是2003年绘制的,

Explore More
::探索更多

Use the resource below to answer the questions that follow.
::利用以下资源回答以下问题。

1. What happened on April 18, 1906?
   ::1906年4月18日发生了什么?

1. How fast is movement usually along San Andreas Fault? What is the rate of movement during a major quake?
   ::圣安德烈亚斯断层沿线的移动速度通常有多快? 重大地震期间的移动速度是多少?

1. Why is it difficult to predict earthquakes?
   ::为什么很难预测地震?

1. What information would a really great earthquake prediction give?
   ::真正伟大的地震预测能提供什么信息?

1. What can provide a warning for earthquakes about 10% of the time? Why is this warning system not all that reliable?
   ::在大约10%的时间里,什么能为地震提供警告?为什么这个警报系统不那么可靠?

1. Why is monitoring the Earth from space useful? What does it tell scientists?
   ::为什么从空间监测地球有用?它告诉科学家什么?