GMAT考试 4月9日更新GMAT阅读机经(十七).

　　GMAT考试已于2012年4月2日更换题库，以下是2012年4月的GMAT阅读机经更新，更新日期从2012年4月2日起，澳际留学小编将为您提供最新的GMAT阅读机经。说明：*代表考古，绿色代表考古标志，凡是未确认的都有红标，没红标的就是已经确认了；粉色代表参考答案；红色代表重要提示；靛蓝代表参考文献，各种底色代表问题答案所对应的原文段落，详情请见问题后面的粉色描述。澳际留学在此祝大家GMAT考试顺利!

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。

　　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。

　　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(第一段是重点)

　　In most earthquakes theEarth’s crust cracks like porcelain, Stress builds up until a fracture forms ata depth of a few kilometers and the crust (5) slips to relieve the stress. Someearthquakes, however, take place hundreds of kilometers down in the Earth’smantle, where high pressure makes rock so ductile that it flows instead of (10)cracking, even under stress severe enough to dorm it like putty. How canthere be earthquakes at such depths? That such deep events do occur has beenaccepted only since 1927 when the seismologist Kiyoo Wadati convincinglydemonstrated their existence. Instead of comparing the arrival times of seismicwaves at different locations, as earlier researchers had done, Wadati relied ona time difference between the arrival of primary(P) waves and the slower secondary(S) waves. Because P and Swaves travel at different but fairly constant speeds, the interval between theirarrivals increases in proportion to the distance from the earthquake focus, orinitial rupture point.

　　For most earthquakes,Wadati discovered, the interval was quite short near the epicenter; the pointon 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 common shallow events, in which the focus lay just under the epicenter, and deep events, with a focus several hundred kilometers down.

　　The question remained: howcan such quakes occur, given that mantle rock at a depth of more than 50kilometers is too ductile to store enough stress to fracture? Wadati’s work suggestedthat deep events occur in areas (now called Wadati-Benioff zones) where onecrustal plate is forced under another and descends into the mantle. Thedescending rock is substantially cooler than the surrounding mantle and henceis less ductile and much more liable to fracture.

　　以上就是4月9日更新的GMAT阅读机经，考生可以适当借鉴，并通过练习来掌握GMAT阅读的解题规律，从而在GMAT考试中发挥出更好的水平。 相关链接：

1.GMAT阅读常见题型解题攻略：类比题

2.GMAT考试 4月10日更新GMAT逻辑机经（四）

3.GMAT考试 4月9日更新GMAT阅读机经(十八)

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