64 Tsunami!-High

Tsunami! FOCUS Question What are the causes and effects of tsunamis?

海啸!海啸的起因和影响是什么?

What Is a Tsunami? A giant wall of water swamps a coastal town in mere minutes. This is no regular ocean wave— it's a tsunami! A tsunami (tsoo-NAH-mee) is a group of huge ocean waves that rush onshore. Regular ocean waves are caused by wind, but tsunami waves are caused by sudden movements of the ocean floor. Tsunami waves are fast and dangerous, traveling far across the ocean at up to 966 kilometers per hour (600 mph) before they reach land. That's faster than a jet airplane! Word Wise Tsunamis are not "tidal waves." Tsunamis are caused by geologic movements, not by tides.

海啸是什么?一堵巨大的水墙在几分钟内淹没了一个沿海城镇。 这不是普通的海浪，这是海啸!海啸是一组巨大的海浪冲上岸。 普通的海浪是由风引起的，但海啸是由海底的突然运动引起的。 海啸波快速而危险，在到达陆地之前，它们可以以每小时966公里(600英里/小时)的速度穿过海洋。 这比喷气式飞机还快!海啸不是“潮汐波”。 海啸是由地质运动引起的，而不是潮汐。

Making Waves Underwater earthquakes are the most common cause of tsunamis. Earth's surface is made up of many enormous, rocky plates. Earthquakes happen where two plates rub together and slide past each other. When an earthquake shakes the land under an ocean, the seafloor gets pushed up. This force pushes on the water and can trigger a tsunami. The waves that form move outward in every direction from the source of the earthquake. Several of Earth's plates meet in the Pacific Ocean. Earthquakes and tsunamis occur more frequently there than in other places. Of course, earthquakes don't only happen under the ocean. They sometimes cause landslides that suddenly force rocks and soil into the ocean. This sudden movement is another cause of tsunamis.

水下地震是引发海啸的最常见原因。 地球表面由许多巨大的岩石板块组成。 地震发生在两个板块相互摩擦和滑动的地方。 当地震震动海洋下的陆地时，海底就会被推高。 这种力量推动着海水，并可能引发海啸。 形成的地震波从震源向四面八方扩散。 地球上的几个板块在太平洋交汇。 那里的地震和海啸比其他地方更频繁。 当然，地震不仅仅发生在海底。 它们有时会导致山体滑坡，突然迫使岩石和土壤进入海洋。 这种突然的移动是海啸的另一个原因。

Landslides also happen underwater when large amounts of rock and dirt on the ocean floor move suddenly. If this disturbance is strong enough to affect the water above, a tsunami forms. In 1998, a terrible tsunami hit the coast of Papua New Guinea. This tsunami was caused by an underwater landslide. Volcanic eruptions above and below the ocean's surface can also result in powerful waves. When volcanoes erupt, rock and debris fall into the ocean and push the water, causing a tsunami. In 1883, a volcano known as Krakatau erupted in Indonesia, causing a tsunami that harmed people hundreds of kilometers away.

当海底大量岩石和泥土突然移动时，水下也会发生山体滑坡。 如果这种扰动强到足以影响上面的海水，就会形成海啸。 1998年，一场可怕的海啸袭击了巴布亚新几内亚海岸。 这次海啸是由水下滑坡引起的。 海面上和海面下的火山爆发也会产生强烈的海浪。 当火山爆发时，岩石和碎片落入海洋，推动海水，引发海啸。 1883年，印度尼西亚喀拉喀托火山爆发，引发海啸，数百公里外的人受到伤害。

Hazards and Warnings Whatever the cause, a tsunami is a natural hazard— a natural event that causes damage and endangers people. Any low area near a coast is at risk. At first, a tsunami may cause the water near the shore to retreat, making a beach seem bigger and exposing the ocean floor. Then the first wave hits. The danger can last for hours afterward as more waves keep hitting. The waves can flood the land hundreds of meters inland with a wall of fast-moving water, taking many lives in the process. On beaches, they can cause erosion— the destruction of an area as sand, sediment, rocks, and plants are cleared away by the force of the water. Waves can easily sweep up heavy boulders, boats, and cars, carrying them inland. The waves can also destroy buildings, bridges, and roads.

无论原因是什么，海啸都是一种自然灾害——一种造成破坏并危及人类的自然事件。 任何靠近海岸的低洼地带都有危险。 起初，海啸可能会导致海岸附近的海水后退，使海滩看起来更大，并暴露海底。 然后第一波来袭。随着更多的海浪不断袭来，危险可能会持续数小时。 海浪可以用快速流动的水墙淹没内陆数百米的土地，在这个过程中夺去许多人的生命。 在海滩上，它们会造成侵蚀——当沙子、沉积物、岩石和植物被水的力量冲走时，会对一个地区造成破坏。 海浪可以很容易地卷起沉重的巨石、船只和汽车，把它们带到内陆。 海浪还能摧毁建筑物、桥梁和道路。

Because they can happen very suddenly, earthquakes, landslides, and volcanic eruptions are hard to predict. As a result, scientists do not know where or when the next tsunami will strike. But once a tsunami starts, they can detect it with special machines. Tsunami warning centers are run by scientists working all around the world. These experts use tsunami detectors placed in the deep ocean to record movements of the water. Then they use computer models to predict where and when the dangerous waves may hit. The centers warn officials of the threat with the hope of reducing the loss of life and property. Fact or Fiction? Objects from space can cause tsunamis. That's a fact! About two million years ago, a huge asteroid struck the ocean near Chile. It caused a tsunami that swamped parts of South America and Antarctica.

由于地震、山体滑坡和火山爆发可能发生得非常突然，因此很难预测。 因此，科学家不知道下一次海啸会在何时何地发生。 但是一旦海啸开始，他们可以用特殊的机器探测到。 海啸预警中心由世界各地的科学家管理。 这些专家使用放置在深海的海啸探测器来记录海水的运动。 然后他们使用计算机模型来预测危险海浪可能会在何时何地袭击。 这些中心警告官员这一威胁，希望减少生命和财产损失。 事实还是虚构?来自太空的物体可以引发海啸。 这是事实!大约200万年前，一颗巨大的小行星撞击了智利附近的海洋。 它引发的海啸淹没了南美洲和南极洲的部分地区。