How tsunamis work - Alex Gendler

标题： 海啸是怎么回事 - Alex Gendler

翻译人员: Catherine Gu 校对人员: Jia (Jolie) YU

公元前479年波斯士兵围攻

In 479 BC, when Persian soldiers besieged

the Greek city of Potidaea,

希腊城市波提狄亚时，

the tide retreated much farther than usual,

潮水比平时退得更远，

leaving a convenient invasion route.

留下了一条便捷的入侵路线。

But this wasn't a stroke of luck.

但这不是意外的好运。

Before they had crossed halfway,

士兵们还没走到一半，

the water returned in a wave higher than anyone had ever seen,

高过以往见过的

回流的水波

drowning the attackers.

就淹死了这些进攻者。

The Potiidaeans believed they had been saved

波提狄亚人认为他们得救于

by the wrath of Poseidon.

波塞冬的愤怒。

But what really saved them

但真正救了他们的可能是

was likely the same phenomenon that has destroyed countless others:

已摧毁过无数他人的同样的现象：

a tsunami.

海啸。

Although tsunamis are commonly known as tidal waves,

虽然海啸通常被称为潮汐波，

they're actually unrelated to the tidal activity caused

它们实际与太阳和月亮引起的

by the gravitational forces of the Sun and Moon.

潮汐活动无关。

In many ways, tsunamis are just larger versions of regular waves.

在许多方面，海啸只是

比正常波浪还大的波浪。

They have a trough and a crest,

它们有波谷和波峰，

and consist not of moving water,

并不是流动的水，

but the movement of energy through water.

而是水的能量运动。

The difference is in where this energy comes from.

区别在于这种能量是从哪里来的。

For normal ocean waves, it comes from wind.

正常的海波

来自风。

Because this only affects the surface, the waves are limited in size and speed.

由于风只影响表面，

波浪的大小和速度是有限的。

But tsunamis are caused by energy originating underwater,

但海啸是由

水下的能量引起的，

from a volcanic eruption,

（比如）火山爆发ˎ

a submarine landslide,

海底滑坡ˎ

or most commonly, an earthquake on the ocean floor

或最常见的，

地球表面的板块滑动引起的

caused when the tectonic plates of the Earth's surface slip,

海底地震

releasing a massive amount of energy into the water.

向水里释放出大量的能量。

This energy travels up to the surface,

这能量向上行进到表面，

displacing water and raising it above the normal sea level,

排开水且使水面高于

正常的海平面，

but gravity pulls it back down,

但重力把它拉下来，

which makes the energy ripple outwards horizontally.

使得能量向外横向传播。

Thus, the tsunami is born,

因此，海啸就出现了，

moving at over 500 miles per hour.

以每小时500英里以上的速度行进

When it's far from shore, a tsunami can be barely detectable

当海啸远离海岸时，

海啸几乎不能被探测到，

since it moves through the entire depth of the water.

因为海啸通过整个水深移动。

But when it reaches shallow water, something called wave shoaling occurs.

但当海啸到达浅水地带，

波变浅的情况就发生了。

Because there is less water to move through,

因有较少的水移动，

this still massive amount of energy is compressed.

这巨大的能量被压缩。

The wave's speed slows down,

水波的速度慢了，

while its height rises to as much as 100 feet.

但水波的高度升起高达100英尺。

The word tsunami, Japanese for "harbor wave,"

海啸这个词，

日语叫“港波，

comes from the fact that it only seems to appear near the coast.

来源于

它似乎只出现在海岸附近这一事实。

If the trough of a tsunami reaches shore first,

如果海啸的低谷先到达海岸，

the water will withdraw farther than normal

在波浪撞击之前，水会比正常情况下退出的距离更远，

before the wave hits,

这种情况既危险又有误导性。

which can be misleadingly dangerous.

A tsunami will not only drown people near the coast,

海啸不仅会淹死靠近海岸的人，

but level buildings and trees for a mile inland or more,

还会把内陆一英里或更远距离的建筑物和树木冲平，

especially in low-lying areas.

特别是在低洼的地方。

As if that weren't enough, the water then retreats,

好像这还不够，

水然后再退下来，

dragging with it the newly created debris,

随之脱下来的还有新产生的碎片，

and anything, or anyone, unfortunate enough

以及路途中极不幸

to be caught in its path.

被冲走的任何东西或人。

The 2004 Indian Ocean tsunami

2004年印度洋发生的海啸

was one of the deadliest natural disasters in history,

是历史上一次最致命的自然灾害之一，

killing over 200,000 people throughout South Asia.

在整个南亚地区死了超过200,000人。

So how can we protect ourselves against this destructive force of nature?

因此怎样才能保护我们

抵抗这种大自然的破坏力呢？

People in some areas have attempted

某些地区的人们试图

to stop tsunamis with sea walls, flood gates,

用海堤、防洪门

and channels to divert the water.

和渠道疏导水来阻止海啸。

But these are not always effective.

但这些并不总起作用。

In 2011, a tsunami surpassed the flood wall

2011年的海啸超越了

protecting Japan's Fukushima Power Plant,

保护日本福岛电厂的防洪墙，

causing a nuclear disaster

引起核灾难，

in addition to claiming over 18,000 lives.

造成超过18,000人丧生。

Many scientists and policy makers are instead focusing on early detection,

许多科学家和政策制定者

却集中在早期发现，

monitoring underwater pressure and seismic activity,

监测水下压力和地震活动，

and establishing global communication networks

并建立全球通信网络

for quickly distributing alerts.

以快速发送警报。

当自然太强大而无法阻止它时，

When nature is too powerful to stop,

the safest course is to get out of its way.

最安全的做法是为其让道。