“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.
詞匯：
subduction /sb'dkn/ n.俯沖 sediment /'sedimnt/ n.沉積;沉淀物
liquefaction /likwi'fkn/ n.液化 infrastructure /'Infr,strkt/ n.基礎(chǔ)設(shè)施
geotecnical /diu'teknikl] adj.巖土技術(shù) compaction /km'pkn/ n.壓緊的
vulnerable /'vlnrbl/ ad].易受傷害的
注釋：
1. subduction zone：俯沖帶。亦稱下降帶、潛沒帶、消亡帶。板塊構(gòu)造說認(rèn)為，當(dāng)大洋板塊移動并與大陸板塊相遇時，由于大洋板塊巖石密度較大，地位也低，便俯沖到大陸板塊之下，這一俯沖部分叫做俯沖帶。俯沖帶兩側(cè)板塊會聚邊界稱會聚邊緣(convergent boundary)。俯沖帶上面反映震源活動的地帶稱“貝尼奧夫地震帶(Benioff seismic zone)"。
2. soil "liquefaction"：土壤液化。土壤液化現(xiàn)象是指由于孔隙水壓力上升，有效應(yīng)力減小所導(dǎo)致的土壤從固態(tài)到液態(tài)的變化，飽水的疏松的粉、細(xì)砂土在振動作用下突然破壞而呈現(xiàn)液態(tài)的現(xiàn)象。
3. localized：小范圍的
4. geotechnical engineering：巖土工程。
5. Oregon State University：俄勒岡州立大學(xué)，建校于1858年，位于美國俄勒岡州科瓦利斯，全校設(shè)11個學(xué)院，80多個專業(yè)，尤以農(nóng)科和工程最為突出。2008年俄勒岡州立大學(xué)的核能工程專業(yè)在全美大學(xué)中排名第9名。
6. water, drain and gas pipelines：自來水管道、排水管道和煤氣管道。"water, drain and gaspipelines” 即“water pipelines, drain pipelines and gas pipelines"。
7. some degree of soil liquefaction：某種程度的土壤液化
8. to reconsider the extent of liquefaction damage possibly occurring in situations such as this：本句的意思是：重新審視類似這次(持續(xù)時間長的)地震中因土壤液化而可能造成的毀壞的規(guī)模。
9. recovery efforts：重建工作
10. that we'll learn things from what happened in Japan：我們將從日本的地震中學(xué)到很多東西。該句是同位語從句，說出前半句no doubt的內(nèi)容。
11. that：that引導(dǎo)的是定語從句，修辭前半句中的things。
12.suspect：被懷疑對象。文中指的是那些疑似危險的土壤。
練習(xí)：
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
答案與題解：
1.D前文說到日本的俯沖帶地震是massive(巨大的)，而且砂土液化到達(dá)一個significant level。根據(jù)上述描述，選widespread(分布廣泛的)修飾severity是正確的。其他三個選項與severity搭配后，意思接不上。
2.C 本句由but連接并列的兩個分句組成。第一個分句說以前也發(fā)生過地震引發(fā)的砂土液化的現(xiàn)象，但涉及范圍較小。第二個分句通過but語氣一轉(zhuǎn)，說這次地震造成的破壞是罕見的。很顯然，選extent(程度)與distance(距離，范圍)合用說明破壞的程度和范圍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...”是定語從句，指代utilities和infrastructure的關(guān)系代詞which在定語從句中起賓語作用，被省略了。need
后面的動詞不定式的邏輯主語是which，也就是utilities and infrastructure。從意思上看，這
些社區(qū)需要這些公用事業(yè)設(shè)備和基礎(chǔ)設(shè)施起功能作用(function)。選function是對的。其他選項都不合適。
4.B 浸了水的砂土，特別是新近的沉積土、沙土等失去的不會是durability(耐用性)和ability(能力)，也不會是泛泛的property(性質(zhì))，而是strength(強度)。
5.C 浸了水的砂土強度降低或消失。砂土隨水流動，就會引發(fā)建筑物移位(shift)或下沉(sink)。再發(fā)展下去，建筑物就會倒塌(collapse)。collapse是答案。若選擇ascend(上升)、compact(壓實)或recover(復(fù)原)，意思與上文接不上。
6.A 地震持續(xù)的時間一般為數(shù)十秒。這次日本地震的時間長達(dá)5分鐘。所以本題要填入的詞應(yīng)該是shorter，說明大多數(shù)地震的持續(xù)時間比它短。
7.C 從意思上看，選how是正確的。when structures、what structures或which structures意思明顯不通。
8.D 第三段第二句出現(xiàn)“particularly recent sediment…"。recent sediment浸水后就失去了強度。這提示了本題要選recently，因為建立在新近填就的土壤上的建筑物是最易受到傷害的。
9.B 分析日本大地震得出的數(shù)據(jù)不會令科學(xué)家獲得有關(guān)soil development(土壤發(fā)展)、soil
formation(土壤形成)soil composition(土壤構(gòu)成)這些方面的知識。若選phenomenon，意思就是科學(xué)家的研究分析有助于他們了解到土壤浸水后的這類現(xiàn)象，以便做好防備，對付
未來可能發(fā)生的同類現(xiàn)象。上下文意思很連貫，因此phenomenon是正確的選項。
1O.D 選unless、until或after都不合邏輯。本題句子的意思是：重建工作首先要清理廢墟，這樣地震現(xiàn)場就被破壞了。所以科學(xué)家要趕在重建工作開始之前收集好地震資料。before是答案。
11.C 本句的意思是：科學(xué)家無疑會從日本大地震中學(xué)到不少東西，從而有助于減低今后發(fā)生類似的地震時的風(fēng)險。四個選項中只有events合適。similar events指的是“類似的地震事
件”。若選findings(調(diào)查結(jié)果)、locations(地點)或sources(來源)，句子的意思就不對。
12.B 本句解釋“young”這個詞在地質(zhì)學(xué)中的含義。句中的those指代sediments。"young" sediments指那些年代少于或略超過一萬年的sediments。deposit是“沉積”，與句子意思匹配，是答案。其他三個選項，詞義離題很遠(yuǎn)，只是詞形與deposit有點相似，起干擾作用而已，它們不是答案。
13.A 上一段說，younger soils是非常脆弱的。本句的anything指的是soils。哪些地方的soils是疑似高危對象呢?如果指soils from/inside/over river and old flood plains是不合常理的。正確的選擇應(yīng)該是near，靠近河流和原洪泛區(qū)的土壤才是危險地區(qū)。因此near是答案。
14.A 加固危橋的目的是為了防止坍塌。選項prevent是答案。
15.D 在3月11日的日本大地震中，震區(qū)的建筑物傾斜、下沉，但沒有倒塌。建筑上的什么因素起到了防塌的作用呢?當(dāng)然不會是construction styles(建筑風(fēng)格)、construction sites(建
筑工地)或construction facilities(建筑設(shè)備)。日本的construction standards(建筑標(biāo)準(zhǔn))才是防塌的關(guān)鍵因素。因此standards是答案。