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火山与水

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小编摘要:消防员用水来扑灭熊熊燃烧的大火,你或许想知道水是否也可以用来扑灭喷发的火山。事实上,每次海底火山喷发就是对此进行的一个实验。当海底火山喷发时,都发生了什么呢?

 Volcanos and Water



Firefighters use water to battle a towering inferno.You might wonder if water could also stifle an erupting volcano. Actually, this experiment happens every time a volcano erupts at the bottom of the ocean. What happens when a volcano erupts underwater? We'll find it out in today's moment of science.

Most of the world’s volcanic action happens an average of eight thousand five hundred feet underwater. Deep beneath the waves there are an estimated one million volcanos. As with land volcanos, molten lava pushes up from beneath the sea floor at thousands of degrees Fahrenheit.

Ocean water can’t “put out” the volcano the way firefighters put out a fire, but it does have a profound effect on what happens to the lava once it’s out of the ground. The biggest difference between undersea and land volcanos has nothing to do with water’s wetness, but with its pressure.

At these depths, the water pressure can be two hundred and fifty times more powerful than air pressure at the Earth’s surface. This prevents bubbles from forming in the lava, eliminating the likelihood of an explosive eruption like some land eruptions are.

Instead, lava squeezes out of the ground like toothpaste out of a tube, forming glassy rock formations that look like long, stacked pillows. The pressure is so high that steam never even forms where lava touches water. You could be in a boat over a giant, erupting volcano, and never even know it was there.

So,you can’t put out a volcano with water. But on our next program, we’ll find out what happened to a town that tried to do this anyway–and in a way succeeded!

火山与水

消防员用水来扑灭熊熊燃烧的大火,你或许想知道水是否也可以用来扑灭喷发的火山。事实上,每次海底火山喷发就是对此进行的一个实验。当海底火山喷发时,都发生了什么呢?我们今天就跟随科学一刻栏目一起探个究竟吧。

世界上大多数的火山活动都发生在海平面以下平均8500英尺的地方。在海底大约有一百万座火山。至于地面上的火山,就是由华氏几千度的炽热的岩浆从海底向上冲出而成。

海水并不能像消防员灭火一样扑灭火山,但是当岩浆冲出地面时,它确实能起到不小的作用。扑灭海底火山和地面的火山最大的不同在于水的压力,与水的湿度并没有关系。

在这样的深度,水压可以是地面上空气压力的250多倍。压力可以阻止岩浆中形成气泡,这也就消除了地面火山爆炸性喷发的可能性。

相反,岩浆就像牙膏挤出管子那样挤出地面,形成一道道玻璃般的岩层,看起来就想是一条长长的堆叠的枕头。压力是如此巨大,以至于这些岩石接触到海水时连水蒸汽都还无法形成。因此,你或许就曾经驾船行驶在一个巨大的喷发的火山上而丝毫没有察觉。

所以,用水不可能扑灭火山。但是在我们下一期的节目中我们将会告诉您一个镇子曾经试图这样做,而且从某种程度上来说,他们成功了!

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2012-03-07 21:25 编辑:pliny
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