“Liquefaction” Key to Much of Japanese Earthquake Damage
The massive subduction zone1 earthquake in Japan caused a significant level of soil
"liquefaction"2 that has surprised researchers with its 1 severity, a new analysis shows.
"We've seen localized3 examples of soil liquefaction as extreme as this before, but the distance and 2 of damage in Japan were unusually severe," said Scott Ashford, a professor of geotechnical engineering4 at Oregon State University5. "Entire structures were tilted and sinking into the sediments," Ashford said. "The shifts in soil destroyed water, drain and gas pipelines6, crippling the utilities and infrastructure these communities need to 3 . We saw some places that sank as much as four feet."
Some degree of soil liquefaction7 is common in almost any major earthquake. It's a phenomenon in which soils soaked with water, particularly recent sediments or sand, can lose much of their 4 and flow during an earthquake. This can allow structures to shift or sink or 5 .
But most earthquakes are much 6 than the recent event in Japan, Ashford said. The length of the Japanese earthquake, as much as five minutes, may force researchers to reconsider the extent of liquefaction damage possibly occurring in situations such as this8.
"With such a long-lasting earthquake, we saw 7 structures that might have been okay after 30 seconds just continued to sink and tilt as the shaking continued for several more minutes," he said. "And it was clear that younger sediments, and especially areas built on 8 filled ground, are much more vulnerable."
The data provided by analyzing the Japanese earthquake, researchers said, should make it possible to improve the understanding of this soil 9 and better prepare for it in the future. Ashford said it was critical for the team to collect the information quickly, 10 damage was removed in the recovery efforts9.
"There's no doubt that we'll learn things from what happened in Japan10 that11 will help us to reduce risks in other similar 11 ," Ashford said. "Future construction in some places may make more use of techniques known to reduce liquefaction, such as better compaction to make soils dense, or use of reinforcing stone columns."
Ashford pointed out that northern California have younger soils vulnerable to liquefaction ---on the coast, near river deposits or in areas with filled ground. The "young" sediments, in geologic terms, may be those 12 within the past 10,000 years or more. In Oregon, for instance, that describes much of downtown Portland, the Portland International Airport and other cities.
Anything 13 a river and old flood plains is a suspect12, and the Oregon Department of Transportation has already concluded that 1,100 bridges in the state are at risk from an earthquake. Fewer than 15 percent of them have been reinforced to 14 collapse. Japan has suffered tremendous losses in the March 11 earthquake, but Japanese construction 15 helped prevent many buildings from collapse ---even as they tilted and sank into the ground.
词汇：
subduction /sb'dkn/ n.俯冲 sediment /'sedimnt/ n.沉积;沉淀物
liquefaction /likwi'fkn/ n.液化 infrastructure /'Infr,strkt/ n.基础设施
geotecnical /diu'teknikl] adj.岩土技术 compaction /km'pkn/ n.压紧的
vulnerable /'vlnrbl/ ad].易受伤害的
注释：
1. subduction zone：俯冲带。亦称下降带、潜没带、消亡带。板块构造说认为，当大洋板块移动并与大陆板块相遇时，由于大洋板块岩石密度较大，地位也低，便俯冲到大陆板块之下，这一俯冲部分叫做俯冲带。俯冲带两侧板块会聚边界称会聚边缘(convergent boundary)。俯冲带上面反映震源活动的地带称“贝尼奥夫地震带(Benioff seismic zone)"。
2. soil "liquefaction"：土壤液化。土壤液化现象是指由于孔隙水压力上升，有效应力减小所导致的土壤从固态到液态的变化，饱水的疏松的粉、细砂土在振动作用下突然破坏而呈现液态的现象。
3. localized：小范围的
4. geotechnical engineering：岩土工程。
5. Oregon State University：俄勒冈州立大学，建校于1858年，位于美国俄勒冈州科瓦利斯，全校设11个学院，80多个专业，尤以农科和工程最为突出。2008年俄勒冈州立大学的核能工程专业在全美大学中排名第9名。
6. water, drain and gas pipelines：自来水管道、排水管道和煤气管道。"water, drain and gaspipelines” 即“water pipelines, drain pipelines and gas pipelines"。
7. some degree of soil liquefaction：某种程度的土壤液化
8. to reconsider the extent of liquefaction damage possibly occurring in situations such as this：本句的意思是：重新审视类似这次(持续时间长的)地震中因土壤液化而可能造成的毁坏的规模。
9. recovery efforts：重建工作
10. that we'll learn things from what happened in Japan：我们将从日本的地震中学到很多东西。该句是同位语从句，说出前半句no doubt的内容。
11. that：that引导的是定语从句，修辞前半句中的things。
12.suspect：被怀疑对象。文中指的是那些疑似危险的土壤。
练习：
1.A.internal B. different C. difficult D. widespread
2.A.volume B. length C. extent D. width
3.A.function B. repair C. build D. remove
4.A.durability B. strength C. ability D. property
5.A.ascend B. compact C. collapse D. recover
6.A.shorter B. longer C. simpler D. stranger
7.A.when B. what C. how D. which
8.A.occasionally B. frequently C. specially D. recently
9.A.development B. phenomenon C. formation D. composition
10.A.unless B. until C. after D. before
11.A.findings B. locations C. events D. sources
12.A.delivered B. deposited C. destroyed D. detached
13.A.near B. from C. inside D. over
14.A.prevent B. accelerate C. predict D. detect
15.A.styles B. sites C. costs D. standards
答案与题解：
1.D前文说到日本的俯冲带地震是massive(巨大的)，而且砂土液化到达一个significant level。根据上述描述，选widespread(分布广泛的)修饰severity是正确的。其他三个选项与severity搭配后，意思接不上。
2.C 本句由but连接并列的两个分句组成。第一个分句说以前也发生过地震引发的砂土液化的现象，但涉及范围较小。第二个分句通过but语气一转，说这次地震造成的破坏是罕见的。很显然，选extent(程度)与distance(距离，范围)合用说明破坏的程度和范围是符合上下文的意思的。
3.A 在“The shifts in soil destroyed water, sewer and gas pipelines, crippling the utilities and infrastructure these communities need to…”中，"these communities need to...”是定语从句，指代utilities和infrastructure的关系代词which在定语从句中起宾语作用，被省略了。need
后面的动词不定式的逻辑主语是which，也就是utilities and infrastructure。从意思上看，这
些社区需要这些公用事业设备和基础设施起功能作用(function)。选function是对的。其他选项都不合适。
4.B 浸了水的砂土，特别是新近的沉积土、沙土等失去的不会是durability(耐用性)和ability(能力)，也不会是泛泛的property(性质)，而是strength(强度)。
5.C 浸了水的砂土强度降低或消失。砂土随水流动，就会引发建筑物移位(shift)或下沉(sink)。再发展下去，建筑物就会倒塌(collapse)。collapse是答案。若选择ascend(上升)、compact(压实)或recover(复原)，意思与上文接不上。
6.A 地震持续的时间一般为数十秒。这次日本地震的时间长达5分钟。所以本题要填入的词应该是shorter，说明大多数地震的持续时间比它短。
7.C 从意思上看，选how是正确的。when structures、what structures或which structures意思明显不通。
8.D 第三段第二句出现“particularly recent sediment…"。recent sediment浸水后就失去了强度。这提示了本题要选recently，因为建立在新近填就的土壤上的建筑物是最易受到伤害的。
9.B 分析日本大地震得出的数据不会令科学家获得有关soil development(土壤发展)、soil
formation(土壤形成)soil composition(土壤构成)这些方面的知识。若选phenomenon，意思就是科学家的研究分析有助于他们了解到土壤浸水后的这类现象，以便做好防备，对付
未来可能发生的同类现象。上下文意思很连贯，因此phenomenon是正确的选项。
1O.D 选unless、until或after都不合逻辑。本题句子的意思是：重建工作首先要清理废墟，这样地震现场就被破坏了。所以科学家要赶在重建工作开始之前收集好地震资料。before是答案。
11.C 本句的意思是：科学家无疑会从日本大地震中学到不少东西，从而有助于减低今后发生类似的地震时的风险。四个选项中只有events合适。similar events指的是“类似的地震事
件”。若选findings(调查结果)、locations(地点)或sources(来源)，句子的意思就不对。
12.B 本句解释“young”这个词在地质学中的含义。句中的those指代sediments。"young" sediments指那些年代少于或略超过一万年的sediments。deposit是“沉积”，与句子意思匹配，是答案。其他三个选项，词义离题很远，只是词形与deposit有点相似，起干扰作用而已，它们不是答案。
13.A 上一段说，younger soils是非常脆弱的。本句的anything指的是soils。哪些地方的soils是疑似高危对象呢?如果指soils from/inside/over river and old flood plains是不合常理的。正确的选择应该是near，靠近河流和原洪泛区的土壤才是危险地区。因此near是答案。
14.A 加固危桥的目的是为了防止坍塌。选项prevent是答案。
15.D 在3月11日的日本大地震中，震区的建筑物倾斜、下沉，但没有倒塌。建筑上的什么因素起到了防塌的作用呢?当然不会是construction styles(建筑风格)、construction sites(建
筑工地)或construction facilities(建筑设备)。日本的construction standards(建筑标准)才是防塌的关键因素。因此standards是答案。