科学家通过短期预警寻求地震警报信号

 

Scientists Seek Earthquake Warning Signs for Short-Term Alerts

科学家通过短期预警寻求地震警报信号

 

The massive recent earthquakes off Indonesia might not have killed so many if they could have been predicted. But earthquake forecasting is still an inexact science, although researchers are trying to improve its precision.

 

Unlike bad weather, earthquakes still take people by surprise. When hurricanes advance, meteorologists can warn people to evacuate¹ areas they expect to be hit, but seismologists cannot provide similar alerts.

 

James Dewey: We just don't have the knowledge that would enable us to issue a short term warning that people could act on.

 

U.S. Geological Survey expert James Dewey says the best that geologists² can do is provide the statistical³ probability of a major ground tremor⁴ based on past history of such activity and on the occurrence of smaller quakes in a region, which might be precursors⁶ to a big one.

 

James Dewey: We prepare maps showing where the probability is highest based on both the geographic⁷ frequency and the frequency with time.

 

Although such probability forecasts cannot save lives when a big shock strikes, they are not useless. At the University of California branch in Davis, seismologist John Rundle says long-term predictions are important for civil engineers and disaster planners in areas prone⁸ to earthquakes.

 

John Rundle: We can stockpile supplies near these hotspot locations. We can improve the roads and infrastructure⁹ in these locations. We can do a lot of things to mitigate¹⁰ the damage that you could not do if I were to come to you and say there is going to be a large earthquake next week.

 

Although short-term earthquake forecasts are not possible, scientists are working to make them a reality. The director of the Southern California Earthquake Center in Los Angeles, Thomas Jordan, says they face a big challenge.

 

Thomas Jordan: The problem is that what's going on down there is very complex and it's very difficult to predict when a small earthquake is going to turn into a big one.

 

The complexity¹¹ relates partly to fault lines. These are where large floating slabs¹² of Earth's rocky crust abruptly¹³ bump against each other or overlap¹⁴, creating the quakes.  Mr. Jordan says it would be easier to predict major movements if they occurred along only one fault line.  But they take place in a complex network of faults, which scientists don't quite know, yet.

 

Thomas Jordan: We need to understand how those complex fault systems actually work, and we've made great progress there. We, in particular, are beginning to understand how faults interact with each other, how one earthquake affects the forces acting¹⁵ on another fault and changes the clock  for that particular fault.

 

The University of Southern California geophysicist says better instruments buried underground or at sea bottom are being used in this research and are helping¹⁶ scientists get better at predicting small quakes, particularly aftershocks of large ones.

 

Scientists are also employing such instruments in their long-standing search for signals that might precede an earthquake. Mr. Jordan says some interesting data are already coming in.

 

Thomas Jordan: We now have detected signals in places like the [U.S.] Pacific Northwest and in Japan that are slow, rhythmic¹⁷ signals that may be associated with the buildup of stress and release of stress at the bottom of these seismogenic zones that may in the future help us anticipate when large earthquakes will occur.

 

A fault running lengthwise through California is the site of a 10-year project to determine if quake warning signals occur.  Beginning later this year, a team led by Stanford University geophysicist Mark Zoback will drill along the fault and bury detectors¹⁸ to measure geophysical movements. They will also retrieve¹⁹ rocks and fluids for analysis.

 

Mark Zoback: Does the surrounding section of the fault slip slowly before the earthquake? Does the fault itself initially²⁰ begin to slip slowly and then accelerate into an earthquake slip? Does the pressure of the water and gasses in the fault change before an earthquake event? Or is there some other signal that might be used as a way of predicting its future occurrence?

 

Satellites in space and strain meters on the ground are being used to measure slight terrain²¹ movements or deformations²² in fault zones to see if they are precursors to earthquakes.

 

Research like this will take a long time, offering people living in seismologically active regions no immediate²³ promise of short-term earthquake prediction. But James Dewey of the U.S. Geological Survey says there is hope.

 

James Dewey: It's possible that with the additional data of the sort that are now being collected that these will come together and point us to a methodology for accurately²⁴ predicting the time and place of an earthquake.

 

David McAlary, VOA news, Washington.

 

注释：

hurricane [5hQrikEn] n. 飓风，狂风

meteorologist [7mi:tjE5rClEdVist] n. 气象学者

evacuate [i5vAkjueit] v. 疏散，撤出

seismologist [saiz5mClEdVist] n. 地震学家

precursor⁵ [pri(:)5kE:sE] n. 先驱

stockpile [5stCkpail] vt. 储蓄，贮存

mitigate [5miti^eit] v. 减轻

aftershock [5B:ftEFCk] n. 余震

anticipate [An5tisipeit] vt. 预期，期望

terrain [5terein] n. 地形

1 evacuate   

v.遣送；搬空；抽出；排泄；大(小)便

参考例句：

• We must evacuate those soldiers at once!我们必须立即撤出这些士兵！
• They were planning to evacuate the seventy American officials still in the country.他们正计划转移仍滞留在该国的70名美国官员。

2 geologists   

地质学家，地质学者( geologist的名词复数 )

参考例句：

• Geologists uncovered the hidden riches. 地质学家发现了地下的宝藏。
• Geologists study the structure of the rocks. 地质学家研究岩石结构。

3 statistical   

adj.统计的，统计学的

参考例句：

• He showed the price fluctuations in a statistical table.他用统计表显示价格的波动。
• They're making detailed statistical analysis.他们正在做具体的统计分析。

4 tremor   

n.震动，颤动，战栗，兴奋，地震

参考例句：

• There was a slight tremor in his voice.他的声音有点颤抖。
• A slight earth tremor was felt in California.加利福尼亚发生了轻微的地震。

5 precursor   

n.先驱者；前辈；前任；预兆；先兆

参考例句：

• Error is often the precursor of what is correct.错误常常是正确的先导。
• He said that the deal should not be seen as a precursor to a merger.他说该笔交易不应该被看作是合并的前兆。

6 precursors   

n.先驱( precursor的名词复数 )；先行者；先兆；初期形式

参考例句：

• Phenyl (or polyphenyl) substituted epoxides serve as excellent precursors to phenyl (or diphenyl) carbenes. 某些苯代（或多苯）环氧乙烷是制取带苯环（或二苯）碳烯的极好原料。 来自辞典例句
• Note the presence of megakaryocytes, erythroid islands, and granulocytic precursors. 可见巨核细胞，红细胞岛和粒细胞前体细胞。 来自互联网

7 geographic   

adj.地理学的，地理的

参考例句：

• The city's success owes much to its geographic position. 这座城市的成功很大程度上归功于它的地理位置。 来自《简明英汉词典》
• Environmental problems pay no heed to these geographic lines. 环境问题并不理会这些地理界限。 来自英汉非文学 - 环境法 - 环境法

8 prone   

adj.(to)易于…的，很可能…的；俯卧的

参考例句：

• Some people are prone to jump to hasty conclusions.有些人往往作出轻率的结论。
• He is prone to lose his temper when people disagree with him.人家一不同意他的意见,他就发脾气。

9 infrastructure   

n.下部构造，下部组织，基础结构，基础设施

参考例句：

• We should step up the development of infrastructure for research.加强科学基础设施建设。
• We should strengthen cultural infrastructure and boost various types of popular culture.加强文化基础设施建设，发展各类群众文化。

10 mitigate   

vt.（使）减轻，（使）缓和

参考例句：

• The government is trying to mitigate the effects of inflation.政府正试图缓和通货膨胀的影响。
• Governments should endeavour to mitigate distress.政府应努力缓解贫困问题。

11 complexity   

n.复杂(性)，复杂的事物

参考例句：

• Only now did he understand the full complexity of the problem.直到现在他才明白这一问题的全部复杂性。
• The complexity of the road map puzzled me.错综复杂的公路图把我搞糊涂了。

12 slabs   

n.厚板，平板，厚片( slab的名词复数 )；厚胶片

参考例句：

• The patio was made of stone slabs. 这天井是用石板铺砌而成的。 来自《简明英汉词典》
• The slabs of standing stone point roughly toward the invisible notch. 这些矗立的石块，大致指向那个看不见的缺口。 来自辞典例句

13 abruptly   

adv.突然地，出其不意地

参考例句：

• He gestured abruptly for Virginia to get in the car.他粗鲁地示意弗吉尼亚上车。
• I was abruptly notified that a half-hour speech was expected of me.我突然被通知要讲半个小时的话。

14 overlap   

v.重叠，与…交叠；n.重叠

参考例句：

• The overlap between the jacket and the trousers is not good.夹克和裤子重叠的部分不好看。
• Tiles overlap each other.屋瓦相互叠盖。

15 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

16 helping   

n.食物的一份&adj.帮助人的，辅助的

参考例句：

• The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
• By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。

17 rhythmic   

adj.有节奏的，有韵律的

参考例句：

• Her breathing became more rhythmic.她的呼吸变得更有规律了。
• Good breathing is slow,rhythmic and deep.健康的呼吸方式缓慢深沉而有节奏。

18 detectors   

探测器( detector的名词复数 )

参考例句：

• The report advocated that all buildings be fitted with smoke detectors. 报告主张所有的建筑物都应安装烟火探测器。
• This is heady wine for experimenters using these neutrino detectors. 对于使用中微子探测器的实验工作者，这是令人兴奋的美酒。 来自英汉非文学 - 科技

19 retrieve   

vt.重新得到，收回；挽回，补救；检索

参考例句：

• He was determined to retrieve his honor.他决心恢复名誉。
• The men were trying to retrieve weapons left when the army abandoned the island.士兵们正试图找回军队从该岛撤退时留下的武器。

20 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

21 terrain   

n.地面，地形，地图

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• He knows the terrain of this locality like the back of his hand.他对这一带的地形了如指掌。

22 deformations   

损形( deformation的名词复数 )； 变形； 畸形； 破相

参考例句：

• It would make no difference if the bar deformations were totally inelastic. 如果杆的变形完全是非弹性变形时这也就没有什么区别了。
• Such readings can reveal longer-period deformations in the earth. 这种读数可以反映地球长周期的形变。

23 immediate   

adj.立即的；直接的，最接近的；紧靠的

参考例句：

• His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
• We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。

24 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。