首页
登录
职称英语
In 1971 researchers hoping to predict earthquakes in the short term by identifyi
In 1971 researchers hoping to predict earthquakes in the short term by identifyi
游客
2024-01-12
35
管理
问题
In 1971 researchers hoping to predict earthquakes in the short term by identifying precursory phenomena (those that occur a few days before large quakes but not otherwise) turned their attention to changes in seismic waves that had been detected prior to earthquakes. An explanation for such changes was offered by "dilatancy theory," based on a well-known phenomenon observed in rocks in the laboratory: as stress builds, microfractures in rock close, decreasing the rock’s volume. But as stress continues to increase, the rock begins to crack and expand in volume, allowing groundwater to seep in, weakening the rock. According to this theory, such effects could lead to several precursory phenomena in the field, including a change in the velocity of seismic waves, and an increase in small, nearby tremors.
Researchers initially reported success in identifying these possible precursors, but subsequent analyses of their data proved disheartening. Seismic waves with unusual velocities were recorded before some earthquakes, but while the historical record confirms that most large earthquakes are preceded by minor tremors, these foreshocks indicate nothing about the magnitude of an impending quake and are indistinguishable from other minor tremors that occur without large earthquakes.
In the 1980s, some researchers turned their efforts from short-term to long-term prediction. Noting that earthquakes tend to occur repeatedly in certain regions, Lindh and Baker attempted to identify patterns of recurrence, or earthquake cycles, on which to base predictions. In a study of earthquake-prone sites along the San Andreas Fault, they determined that quakes occurred at intervals of approximately 22 years near one site and concluded that there was a 95 percent probability of an earthquake in that area by 1992. The earthquake did not occur within the time frame predicted, however.
Evidence against the kind of regular earthquake cycles that Lindh and Baker tried to establish has come from a relatively new field, paleoseismology. Paleoseismologists have unearthed and dated geological features such as fault scarps that were caused by earthquakes thousands of years ago. They have determined that the average interval between ten earthquakes that took place at one site along the San Andreas Fault in the past two millennia was 132 years, but individual intervals ranged greatly, from 44 to 332 years. [br] It can be inferred from the passage that one problem with using precursory phenomena to predict earthquakes is that minor tremors
选项
A、typically occur some distance from the sites of the large earthquakes that follow them
B、are directly linked to the mechanisms that cause earthquakes
C、are difficult to distinguish from major tremors
D、have proven difficult to measure accurately
E、are not always followed by large earthquakes
答案
E
解析
Inference
This question asks what can be inferred from certain information in the passage. The second paragraph explains two problems with using minor tremors to predict earthquakes. First, minor tremors provide no information about how large an impending earthquake will be. Second, the minor tremors that occur prior to a large earthquake are indistinguishable from other minor tremors. Thus, it can be inferred that minor tremors sometimes occur when no large earthquake follows.
A The passage does not mention the distance between minor tremors and ensuing earthquakes.
B The passage implies that minor tremors sometimes occur without an ensuing earthquake, so the phenomena are most likely not directly linked.
C The passage suggests no difficulty in distinguishing between minor tremors and major tremors.
D The passage does not mention any difficulties in the measurement of minor tremors.
E Correct. The passage indicates that minor tremors occurring prior to a large earthquake are indistinguishable from minor tremors that are not followed by large earthquakes. So the fact that minor tremors are not always followed by large earthquakes, together with the inability to distinguish between those that are and those that are not, poses a problem for a ny attempt to predict large earthquakes on the basis of this type of precursory phenomena.
The correct answer is E.
转载请注明原文地址:https://tihaiku.com/zcyy/3357258.html
相关试题推荐
________togetthereontime,wewalkedasfastaswecould.A、HopingB、TohopeC
Theprimarypurposeofthepassageisto______[br]Theresearchers’conclusion
Australianresearchershavediscoveredelectroreceptors(sensoryorgansdesigned
Australianresearchershavediscoveredelectroreceptors(sensoryorgansdesig
Australianresearchershavediscoveredelectroreceptors(sensoryorgansdesig
Australianresearchershavediscoveredelectroreceptors(sensoryorgansdesig
Australianresearchershavediscoveredelectroreceptors(sensoryorgansdesig
Australianresearchershavediscoveredelectroreceptors(sensoryorgansdesig
Earthquakes,volcaniceruptions,andunusualweatherhavecausedmanymorenatur
Itisimpossibletobelievescientificpredictionsthatalong"nuclearwinter"
随机试题
PASSAGETHREE[br]WhatwasMrs.Mallard’smoodwhenshewasleftaloneinther
期货保证金存管银行是由()指定,协助交易所办理期货交易结算业务的银行。A、证监会B、交易所C、期货公司D、银行总部B期货保证金存管银行是由交易所
急性乳腺炎的治疗原则不正确的是()A.消除感染、排空乳汁 B.先抗感染治疗
绿色生态城区实施运管评价阶段应具备相应的条件,下列叙述错误的是( )。A.城区
舞台特殊效果中的焰火分为冷焰火和热焰火,冷焰火,不产生热量但能引燃其他物品。(
患者,女,40岁。不明原因的手足发麻,关节肿痛半年余。开始为手指小关节疼痛,后出
下列关于央行票据的说法不正确的是( )。 I中央银行票据的期限—般在3年以下
根据图标回答 估计每支工具的销售价为多少元?A.400 B.
A.血热 B.气虚 C.血瘀 D.血虚 E.精血亏虚月经过多,色淡质稀的
下列单位或者个人中,一般不是物业管理招标主体的是()。A.物业建设单位
最新回复
(
0
)