英語聽力文摘冰震

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Ice Quake!

美國研究人員發(fā)現(xiàn)，南極洲冰流滑動能產(chǎn)生巨大震波，威力與地震相仿。這是研究人員首次在南極洲發(fā)現(xiàn)“冰震”。華盛頓大學(xué)教授道格拉斯·威恩斯從2001年開始在南極洲周邊地區(qū)設(shè)置多臺地震儀。從當(dāng)年到2003年，地震儀監(jiān)測到多次震波信號。威恩斯說：“起初我們不知道震波來自哪里，但最終我們確定震源為冰流。”監(jiān)測數(shù)據(jù)顯示，這塊冰流寬約100公里，厚約800米。每次移動時，冰流發(fā)出的震波波及整個南極洲，最遠(yuǎn)甚至在澳大利亞都能監(jiān)測到。浙江大學(xué)地球科學(xué)系教授陳漢林進(jìn)一步解釋了“冰震”現(xiàn)象。陳教授指出，這種“冰震”，就相當(dāng)于大型的物體敲擊水面，從而產(chǎn)生震波，與地震類似，而且，根據(jù)各種測定數(shù)據(jù)，也可以核算出震級來，這與炸藥爆炸等產(chǎn)生一定震級的破壞力道理是一樣的。當(dāng)然，這種冰流的規(guī)模要夠大，滑動時能產(chǎn)生足夠大的能量，從而對下面的冰層乃至遙遠(yuǎn)的陸地產(chǎn)生一定的沖擊波。

Over a hundred quakes have happened in the last decade. But they didn't occur near fault lines(斷層線). What were they near? Find out on this Moment of Science.

We’re used to thinking of earthquakes as (1)tremors(震動，顫抖) that happen along fault lines when tectonic plates ((地球表面的)構(gòu)造板塊)shift. They’re dramatic(吸引人注目的) events: a good-sized(相當(dāng)大的，大型的) earthquake can bring buildings and bridges (2)toppling down(推翻;倒塌).

Those destructive energy bursts are high frequency(高頻) ground vibrations(震動), and that’s the range of vibrations seismologists(地震學(xué)家) most actively study. Just recently, though, a geophysicist(地球物理學(xué)者) at Harvard University named G?ran Ekstr?m studied low-frequency(低頻的) vibrations instead, and discovered something interesting.

He found over a hundred quakes have happened in the last decade that aren’t along any fault line. What are they near instead? Ice.

A glacier(冰川) can be thought of as a very (3)slow-moving(動作緩慢的) stream. It’s made of solid ice, but over long periods of time it can flow gradually over the land, sometimes carving deep (4)trenches(溝，溝渠) and (5)bulldozing(推土) up rock and soil. Just because it takes centuries to rearrange(重新排列) things, though, doesn’t mean a glacier isn’t enormously powerful at any given moment.

By carefully measuring seismic(地震的) signals, Ekstr?m was able to spot numerous low-frequency quakes in Greenland that hadn’t been identified. He also found that they mostly occurred during July, August, and September. Those warmer months melt lots of glacial ice.

Ekstr?m suspects that liquid water is (6)pooling(淤積) underneath the glacial ice to the point where the thin (7)veneer(外表) of water at the base of the glacier allows the whole mass to slip(滑動) a little, the way your foot can skid(打滑) on a slick(光滑的) road.

The quakes he recorded, he believes, are the vibrations set up by all that ice–in one case, six cubic(立方的) miles of it–skidding as much as forty-two feet in under a minute. When that much ice scrapes(刮掉，擦掉), the earth itself shakes.

Notes:

(1)tremors ['trem?z] n.震動;顫抖(tremor的復(fù)數(shù))v.顫動(tremor的三單形式)

1.They got only blushes, ejaculations, tremors, and titters, in return for their importunity.

她們只是用臉紅、驚叫、顫抖和傻笑來回答他們的要求。

2.Rescuers are continuing into a third day the hunt for survivors of the earthquake that hit Peru's central coast, as fresh tremors shake the area.

救援一直持續(xù)到了第三天，搜尋發(fā)生在秘魯中部海岸的地震后的幸存者，這次地震又引起了這個地區(qū)的震動。

(2)topple down 推翻;倒塌

The wounded soldier toppled down time after time.

傷兵一次又一次地跌倒。

(3)slow-moving ['sl?u'mu:vi?] adj.滯銷的;動作緩慢的

We looked like a bunch of awkward kids riding a slow-moving carousel.

我們看起來就像一群騎在旋轉(zhuǎn)木馬上的笨拙的孩子。