首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
An accidental discovery has brought seismologists(地震学家) one step closer to being able to predict earthquakes. As part of an unre
An accidental discovery has brought seismologists(地震学家) one step closer to being able to predict earthquakes. As part of an unre
admin
2010-11-02
79
问题
An accidental discovery has brought seismologists(地震学家) one step closer to being able to predict earthquakes. As part of an unrelated effort to measure underground changes caused by shifts in barometric pressure (大气压力), a team of researchers found that increases in subterranean pressure(地下压力) preceded earthquakes along California’s San Andreas Fault(断层) by as much as 10 hours. If follow-up tests advance the findings, seismologists may eventually be able to provide a few hours’ notice for people to find safe places prior to quakes.
Researchers used a high-tech equivalent of a stereo speaker lowered into a bore hole near Parkfield, Calif., a half-mile deep and five yards from a measuring device. For two months beginning in late 2005, researchers transmitted pulse signals three times per second, from the speaker to the measuring device, calculating travel time between the two stations. Surprised scientists learned the seismic waves slowed dramatically on only two occasions: two hours prior to a magnitude-1 temblor (地震), and a startling 10 hours before a magnitude-3 quake.
The research team theorizes that the immense amount of pressure building along the fault causes small cracks within the rock during the final hours before an earthquake, increasing rock density and slowing the transmission signals. "The more cracks you have, the slower the seismic velocity," says study co-author Paul Silver, a geophysicist with the Carnegie Institution of Washington. Still unknown is whether there is any significance to the fact that the magnitude-3 quake had a much longer pre-seismic signal than the lower-magnitude quake, or whether it was simply because its magnitude was larger and its epicenter closer to the sensors.
If scientists can flesh out the new findings during future earthquakes — a two-year study at the same seismically active location begins this September — it could form the basis of a vastly improved early-warning system for quakes. Current earthquake-warning systems give just a few seconds’ notice because they detect only waves, the fast-moving seismic waves that precede the more destructive waves released during a quake. Upgrading to a seismic stress meter, however, is still a long way of{. Researchers hope to test whether the stress signals would still be detectable on a larger scale, with the two sensors spaced more than a few yards apart.
Barring a major effort to drill multiple, half-mile-deep holes along fault lines, researchers would also need to develop a surface-based detection system capable of filtering out temperature swings and other "noise" that could confuse their seismic readings.
It can be learnt from the passage that the current method of earthquake prediction______.
选项
A、provides more accurate data than the new one
B、costs less than the new one
C、costs more than the new one
D、warns people only a few seconds before the earthquake
答案
D
解析
根据题干关键词current method,earthquake prediction定位到第四段第二句:Current earthquake-warning systems give just a few seconds’ notice because they detect only P-waves,the fast-moving seismic waves that precede the more destructive waves released during a quake.可推知目前的预测
转载请注明原文地址:https://kaotiyun.com/show/kQs7777K
0
大学英语六级
相关试题推荐
A、Becausetheyfindsomeworkexceedinglydull.B、Becausetheyfindworklesspainfulthanidleness.C、Becausetheyhavetoomuc
Bullying(欺凌弱小者)atSchool:TacklingtheProblemA.Abroaddefinitionofbullyingiswhenastudentisrepeatedlyexposedto
Directions:Forthispart,youareallowedthirtyminutestowriteacompositiononthetopicHowtoEncouragePeopletoUsePub
Directions:Forthispart,youareallowedthirtyminutestowritealetterofatleast150wordsaccordingtotheoutlinegiven
Doyouseetheglassashalf-fullratherthanhalfempty?Doyoukeepyoureyeuponthedoughnut,notuponthehole?Suddenlyth
Infact,PeterwouldratherhaveleftforSanFrancisco______(而不愿呆在纽约).
Criticismisjudgment.Acriticisajudge.Ajudgemuststudyandthinkaboutthematerialpresentedtoit,【S1】______co
Publicopinionisstilllargelyunawareoforindifferenttotheneedtopreserverarespecies,whetherforculturalorforscie
AJapaneseFundannounced______forwomenforcedintoprostitutionforJapanesesoldiersintheSecondWorldWar.
随机试题
报纸的产量以___________为单位,与产量有关的其他统计指标也以千印张为基本单位。
可引起QRS波群振幅降低的原因是
关于四环素牙的描述,哪项是错误的
为了限制系统短路容量,简化继电保护,环式配电系统应采取开环方式。()
背景资料:某城市地铁标段,包含一段双线区间和一个车站,区间隧道及风道出入口采用暗挖法施工,车站的主体结构采用明挖法施工。区间隧道上方为现况道路,路宽22.5m,道路沿线的地下埋设有雨污水、天然气、电信、热力等管线,另外还有一座公共厕所。隧道埋深
与客户权益变动相关业务的经办人员之间,应当建立()机制。
是否具备()是衡量教师职业道德素质高低的重要标志。
以下所列各项活动中,属于实践活动的是()。①学生听课做作业②教师给学生讲课③经济政治体制改革④中美进行钢铁贸易谈判⑤第六次人口普查⑥蜘蛛织网,蜜蜂采蜜
WhatdoAmericansliketodo?Americansliketolaughand______.
A、Thevalueofknowinghumanhistory.B、Theimportanceofsharinginformation.C、Howtobringbackthreatenedlanguages.D、Whye
最新回复
(
0
)