Level 3 Reading 4B

Ch.8 Reading 4B

第8章 阅读4B

IS PREDICTION POSSIBLE? Never before have so many people been packed into cities—places such as Los Angeles, Istanbul, Tokyo, and Lima— that are regularly affected by earthquakes. Located near the edge of Earth's huge, shifting plates, these cities face the risk of serious damage and economic disaster from large quakes— as well as the tsunamis, fires, and other kinds of destruction they often cause. We understand earthquakes better than we did a century ago. Scientists would like to be able to predict them, but is this possible? Today, some of the simplest questions about earthquakes are still difficult to answer: Why do they start? What makes them stop? Perhaps the most important question scientists need to answer is this: Are there clear patterns in earthquakes, or are they basically random and impossible to predict? In Japan, government scientists say they have an answer to the question. "We believe that earthquake prediction is possible," says Koshun Yamaoka, a scientist at the Earthquake Research Institute at the University of Tokyo. In fact, Japan has already predicted where its next great earthquake will be: the region of Tokai southwest of Tokyo. Here, two plate boundaries have generated huge earthquakes every 100 to 150 years, but there hasn't been a major quake here since 1854. The theory is that stress is building up in this zone, which could lead to a massive quake. Unfortunately, this is more a forecast than a prediction. It's one thing to say that an earthquake is likely to happen in a high-risk area. It's another to predict exactly where and when the quake will occur. The desire for a precise prediction of time and place has led to another theory: the idea of "preslip." Naoyuki Kato, a scientist at the Earthquake Research Institute, says his laboratory experiments show that before a fault in the Earth's crust finally breaks and causes an earthquake, it slips just a little. If we can detect these early slips taking place deep in the Earth's crust, we may be able to predict the next big quake. Clues in the Desert Scientists working in Parkfield, California, are also trying to see if predicting earthquakes is possible. They've chosen the town of Parkfield not only because the San Andreas Fault runs through it, but because it's known for having earthquakes quite regularly—approximately every 22 years. In the late 1980s, scientists in Parkfield decided to study the fault to see if there were any warning signs prior to a quake. To do this, they drilled deep into the fault and set up equipment to register activity. Then they waited for the quake. Year after year, nothing happened. When a quake did finally hit on September 28, 2004, it was years off schedule, but most disappointing was the lack of warning signs. Scientists reviewed the data but could find no evidence of anything unusual preceding the quake. It led many to believe that perhaps earthquakes really are random events. Instead of giving up, though, scientists in Parkfield dug deeper into the ground. By late summer 2005, they had reached the fault's final depth of three kilometers, where they continued collecting data, hoping to find a clue. And then they found something. In an article published in the July 2008 journal Nature, the researchers in Parkfield claimed to have detected small changes in the fault shortly before an earthquake hit. What had they noticed? Just before a quake, the cracks in the fault had widened slightly. Scientists registered the first changes 10 hours before an earthquake of 3.0 on the Richter scale hit; they identified identical signs two hours before a 1.0 quake—demonstrating that perhaps the "pre-slip" theory is correct. In other words, it may in fact be possible to predict an earthquake. Although there is still a long way to go, it appears from the research being done all over the world that earthquakes are not entirely random. If this is so, in the future we may be able to track the Earth's movements and design early-warning systems that allow us to predict when a quake will happen and, in doing so, prevent the loss of life. BUILDING FOR PROTECTION In many of the world's at-risk cities, new structures are designed to survive earthquakes. However, for older structures, engineers need to innovate. These changes help to make the structures stronger, which will reduce damage and allow for quicker repairs.

预测可能吗？ 从来没有这么多人挤进城市，比如洛杉矶、伊斯坦布尔、东京和利马-- 这些地区经常受到地震的影响。 位于地球巨大的、不断移动的板块边缘附近， 这些城市面临着大地震造成的严重破坏和经济灾难的风险-- 以及它们经常造成的海啸、火灾和其他类型的破坏。 我们比一个世纪前更了解地震。 科学家们希望能够预测它们，但这有可能吗？ 今天，关于地震的一些最简单的问题仍然很难回答： 他们为什么开始？是什么让他们停下来的？ 也许科学家们需要回答的最重要的问题是： 地震是否有明确的模式，还是它们基本上是随机的，无法预测？ 在日本，政府科学家表示，他们已经找到了这个问题的答案。 “我们相信地震预测是可能的，”Koshun Yamaoka说， 东京大学地震研究所的科学家。 事实上，日本已经预测了下一次大地震的地点： 东京西南部的东海地区。 这里，两个板块边界每100到150年就会发生一次大地震， 但自1854年以来，这里就没有发生过大地震。 理论上，该地区的应力正在积聚，这可能会导致大地震。 不幸的是，这与其说是预测，不如说是预测。 地震可能发生在高风险地区是一回事。 准确预测地震发生的地点和时间是另一回事。 对精确预测时间和地点的渴望导致了另一种理论：“预测”的想法 地震研究所的科学家加藤直行， 他的实验室实验表明，在地壳断层最终破裂之前 并引发地震，它只会稍微滑动。 如果我们能探测到地壳深处发生的这些早期滑动， 我们也许能够预测下一次大地震。 沙漠中的线索 在加利福尼亚州帕克菲尔德工作的科学家们也在尝试预测地震是否可能。 他们选择帕克菲尔德镇不仅是因为圣安德烈亚斯断层贯穿其中， 但因为它以经常发生地震而闻名，大约每22年一次。 20世纪80年代末，帕克菲尔德的科学家决定研究该断层 看看地震前是否有任何警告信号。 为了做到这一点，他们深入断层并设置设备来记录活动。 然后他们等待着地震。 年复一年，什么都没发生。 当地震最终于2004年9月28日发生时，已经比计划晚了好几年， 但最令人失望的是缺乏警告信号。 科学家们审查了数据，但没有发现地震前有任何异常的证据。 这让许多人相信，地震可能真的是随机事件。 然而，帕克菲尔德的科学家们并没有放弃，而是深入挖掘了地下。 到2005年夏末，他们已经到达了断层最后三公里的深度， 他们继续收集数据，希望找到线索。 然后他们发现了一些东西。 在2008年7月发表在《自然》杂志上的一篇文章中， 帕克菲尔德的研究人员声称，在地震发生前不久，他们发现了断层的微小变化。 他们注意到了什么？就在地震发生前，断层上的裂缝稍微变宽了。 科学家在里氏3.0级地震发生前10小时记录了第一次变化； 他们在1.0级地震前两小时发现了相同的迹象，这表明“预滑”理论可能是正确的。 换句话说，实际上有可能预测地震。 虽然还有很长的路要走，但从世界各地正在进行的研究来看 地震并非完全随机。 如果是这样的话，未来我们可能能够追踪地球的运动并设计预警系统 这使我们能够预测地震何时发生，从而防止生命损失。 保护建筑 在世界上许多有风险的城市，新建筑的设计是为了在地震中幸存下来。 然而，对于较旧的结构，工程师需要创新。 这些变化有助于使结构更坚固，从而减少损坏并加快维修速度。

WAVES OF DESTRUCTION An earthquake's waves come in two forms. P-waves (yellow) arrive fastest and compress and punch the rock. S-waves (red) are slower but more destructive. They move from side to side to shake and destroy buildings. At the ground level, P- and S-waves combine to produce surface waves that crack windows and even destroy bridges.

毁灭的浪潮 地震波有两种形式。 P波（黄色）到达最快，压缩并冲击岩石。 S波（红色）较慢，但更具破坏性。 他们左右移动，摇晃并摧毁建筑物。 在地面，P波和S波结合产生表面波，使窗户破裂，甚至摧毁桥梁。

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