地震那题，考古待确认

mary55111

27*. 地震理论
本篇的英文参考文献经过狗主确认是原文，但是看了看文章以及考古里有些同学说的，估计从第二段开始有变体，
总之大家需要好好看下英文参考文献，尤其第一段。
V1：by 王豆豆豆豆儿
讲地震原来的理论说是怎么怎么形成，应该是在地表一下30mile 以内发生的，然后第二段说但是其实很多地震都
是100 到200 之间的（不记得数了，反正比30 大，100+到200 左右），然后说是什么什么产生的，后面说了一下
两种不同的产生方法。
V2：by VinceGates
第一段讲一个long-established 理论认为地震都发生在接近地面的地方，然后解释了地震为什么不能发生在距离
地面很远的地方的原因，然后举了一个例子，最后说现实情况确实是the majority of earthquakes 发生在近地面
的地方。
后第二段说，但是，有发现却表明，也有不少地震发生自距地面多远多远的地方，然后讲了两种transformation
吧，根据第一种transformation 地震确实不能发生在距离地面很远的地方，但是有人提出了第二种transformation，
这第二种transformation 就使得地震可以发生在距离地面很远的地方了，然后也就能解释为什么也有hundreds of
earthquakes 发生在距离地面很远的地方。
Q1：（v40）主旨题：我在provides a explaination of a scientific puzzle 和 provides an alternative to a long accepted
theory 之间犹豫了很久，选择了替代老观点这一项。
Q2：（v40）第二段高亮部分的作用，我选的还是推翻老观点，建立新理论（选项原文想不起来了，只记得看到这
个题意识到第一题我应该选择正确了。
考古
一段说地震一般发生在离地表很近，大概30mile 的地方（浅层地震）
二段说有一些特别的发生在地下120-400mile，然后一个科学家列出了2 个说法解释深层地震，第一个是P,但是
这种transformation 被否掉了，因为develop 的太慢,接著他又提出第二種說法M,這種說法就可以解釋深層地震的
發生
Q1：主旨题
Q2：第二段的function
Q3：有一个问到了这两个说法的共同点，都change crystalline structure（改变晶体结构）
参考文献（有的同学说是原文 有的说只有第一段相似，总之大家有时间就看看）
In most earthquakes the Earth’s crust cracks like porcelain. Stress builds up until a fracture forms at a depth of a
few kilometers and the crust slips to relieve the stress. Some earthquakes, however, take place hundreds of
kilometers down in the Earth’s mantle, where high pressure makes rock so ductile that it flows instead of cracking,
even under stress severe enough to deform it like putty. How can there be earthquakes at such depths?
That such deep events do occur has been accepted only since 1927, when the seismologist Kiyoo Wadati
convincingly demonstrated their existence. Instead of comparing the arrival times of seismic waves at different
locations, as earlier researchers had done, Wadati relied on a time difference between the arrival of primary (P)
waves and the slower secondary (S) waves. Because P and S waves travel at different but fairly constant speeds,
the interval between their arrivals increases in proportion to the distance from the earthquake focus, or initial
rupture point. For most earthquakes, Wadati discovered, the interval was quite short near the epicenter; the
point on the surface where shaking is strongest. For a few events, however, the delay was long even at the
epicenter. Wadati saw a similar pattern when he analyzed data on the intensity of shaking. Most earthquakes had
a small area of intense shaking, which weakened rapidly with increasing distance from the epicenter, but others
were characterized by a lower peak intensity, felt over a broader area. Both the P-S intervals and the intensity
patterns suggested two kinds of earthquakes: the more (45) common shallow events, in which the focus lay just
under the epicenter, and deep events, with focus several hundred kilometers down.
The question remained: how can such quakes occur, given that mantle rock at a depth of more than 50
kilometers is too ductile to store enough stress to fracture? Wadati’s work suggested that deep events occur in
areas (now called Wadati-Benioff zones), where one crustal plate is forced under another and descends into the
mantle. The descending rock is substantially cooler than the surrounding mantle and hence is less ductile and
much more liable to fracture.

本文体会通篇的对比。
在大多数地震里，地壳瓷般碎裂。压力聚集，直到破裂在数公里深处形成，地壳滑动以释放压力。但是有些地震
在数百公里深的地幔发生，虽然在那里压力巨大，岩石变得柔软，浮动而不破裂。这种地震如何发生？
深层地震到了1927 年才被接受为事实。前人通常比较不同地点震波的到达时间，而KW 则比较P 波和S 波到达
时间的差别。因为P 波和S 波以不同的连续速度行进，它们到达的间隔随震源距离成比例增长。KW 发现，在震
中（地表摇得最厉害的地方）附近的间隔较短，但是某些情况下，即使在震中附近间隔也很长。振动密度数据也
呈类似结果。大多数地震有一个密集振动的范围，振动随震中距离加大而迅速减少，但是另外一种地震的特点是
更广范围更低峰值的强度。P-S 间隔和强度类型都暗示了两种地震：更常见的浅层地震，震源在震中下面；还有
深层地震，震源在数百公里深处。
问题持续：什么导致了深层地震，既然地幔软得不足以存储压力？KW 的实验显示，深层地震出现在一块地壳板
块被另一块挤向下方地幔之处。下降的岩石比周围地幔冷一些，所以不那么软，更容易碎裂。
24-30 The author’s explanation of how deep events occur would be most weakened if which of the following
were discovered to be true?
A) Deep events are far less common than shallow events.
B) Deep events occur in places other than where crustal plates meet.
Wadati’s work suggested that deep events occur in areas (now called Wadati-Benioff zones), where one crustal
plate is forced under another and descends into the mantle.
C) Mantle rock is more ductile at a depth of several hundred kilometers than it is at 50 kilometers.
D) The speeds of both P and S waves are slightly greater than previously thought.
E) Below 650 kilometers earthquakes cease to occur.
24-31 Information presented in the passage suggests that, compared with seismic activity at the epicenter of a
shallow event, seismic activity at the epicenter of a deep event is characterized by
A) shorter P-S intervals and higher peak intensity
B) shorter P-S intervals and lower peak intensity
C) longer P-S intervals and similar peak intensity
D) longer P-S intervals and higher peak intensity
E) longer P-S intervals and lower peak intensity
For most earthquakes, Wadati discovered, the interval was quite short near the epicenter; the point on the
surface where shaking is strongest.将其取非即可
24-32 The passage supports which of the following statements about the relationship between the epicenter and
the focus of an earthquake?
A) P waves originate at the focus and S waves originate at the epicenter.
B) In deep events the epicenter and the focus are reversed.
C) In shallow events the epicenter and the focus coincide
D) In both deep and shallow events the focus lies beneath the epicenter
E) The epicenter is in the crust, whereas the focus is in the mantle.
the more (45) common shallow events, in which the focus lay just under the epicenter, and deep events, with
focus several hundred kilometers down.
24-33 The passage suggests that which of the following must take place in order for any earthquake to occur?
I. Stress must build up
II. Cool rock must descend into the mantle.
III. A fracture must occur.
I only
II only
III only
I and III only
I, II and III

ClaudiaJL

辛苦啦?好爱楼主！！