题目内容
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Crustal rocks can be used to predict earthquakes for their ______.
A．conductivity of electricity
B．hardness to be cracked
C．sensitivity to strain
D．magnetic properties
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更多“Crustal rocks can be used to predict earthquakes for their ______.A．conductivity of electr”相关的问题
One prediction technique involves an analysis of the recurrence rates of earthquakes as indicators of future seismic activity. Earthquakes are concentrated in certain areas of the world where tectonic plates such as the Pacific Plate, the Eurasian Plate and the African Plate meet and create fault zones and it is in these areas that seismologists focus their investigations.
The tectonic plate model provides another tool for earthquake prediction by calculating the accumulated strain at plate boundaries. When the strain reaches a certain magnitude the pressure must be released and it is therefore hypothesized that in such eases an earthquake is imminent.
The search for premonitory phenomena has received particular attention. In contrast to the ancient Greeks and Romans, who relied on the howling of dogs as a warning sign, modern seismologists have focused on physical evidence for an impending earthquake. Evidence of plate strain can be found by measuring relative movements in geodetic stations, while chemical changes also offer signals for seismologists. Using chemical-detection techniques, scientists established a link between the rise in the concentration of radon gas in mineral water and the subsequent earthquake.
Analysis of the changes in magnetic properties and conductivity of rocks provides further data for prediction. The electrical and magnetic properties of crustal rocks particularly sensitive to strain and studies measuring changes which occur in these properties have provided promising results. The conductivity of crustal rock is determined by the degree to which the rock is saturated with fluid and the electrolytic properties of those fluids. Before large earthquakes, small fractures develop in rocks, which change the quantity of fluid present. These changes can be measured and provide useful predictive data. However, similar changes in the fluid-bearing capacity of rock can occur as a result of other factors such as changes in the water table, and therefore this technique is not entirely reliable.
The belief that the behavior. of birds, eats and dogs provides evidence of imminent earthquakes has recently gained credence. It is hypothesized that the animals are sensitive to the seismic waves which precede major quakes.
In zones where earthquakes are known to occur, improved construction techniques can significantly reduce the effects of seismic waves. If more accurate information regarding the time and magnitude were available, governments could take even more effective measures to reduce the impact on human life. If an entirely accurate prediction technique became available, there would be significant social and political implications. An earthquake prediction in a major urban area would require governments to provide an effective evacuation strategy, necessitating massive resource and political will.
Which of the following is true？
A．Earthquakes only occur in the Pacific, Eurasian, and African Plates.
B．Earthquakes are caused by the tectonic plate model.
C．An increase in the level of radon gas in water always indicates an imminent earthquake.
D．The devastation of earthquakes prompted the set, king for reliable prediction methods.
A．To provide an example of a previous idea.
B．To summarize the paragraph.
C．To provide an argument against the previous idea.
D．To establish the main point of the passage.
A．other factors may account for changes in conductivity
B．rock may be saturated with fluid
C．these changes can be measured
D．the conductivity of crustal rock is inherently variable
According to the passage, where can the oldest rocks be found？
A．Near Precambrian schists.
B．Below Precambrian schists.
C．At the bottom of the canyon.
D．In the strata deposited as marine sediment.
A disadvantage of fluid measuring is that＿＿。
A.changes in quantity of fluid in rocks can be caused by other factors other than strain
B.present scientific instruments are not able to provide precise measurement
C.the electrical properties of the rock itself also change the
D.fractures in these rocks are often so serious that accurate measurement is impossible
A.fragments
B.oxidation
C.deterioration
D.frigid
What is the professors purpose in telling the students about moving rocks？
A．To teach a lesson about the structure of solid matter
B．To share a recent advance in geology
C．To give an example of how ice can move rocks
D．To show how geologists need to combine information from several fields
A.put away
B.wear away
C.be exposed to
D.bring back
The main idea of the passage is ______.
A．people feel cool when they are near a lake or an ocean
B．scientists can explain everything we want to know
C．scientists can explain many things but not everything
D．the salt in the ocean comes from rocks
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