“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 /sʌb"dʌkʃən/ n．俯冲        

sediment /"sedimənt/ n．沉积；沉淀物

liquefaction /likwi"fækʃən/ n．液化       

infrastructure /"Infrə,strʌktʃə/ n．基础设施

geotecnical /dʒiəu"teknikəl] adj．岩土技术    

compaction /kəm"pækʃən/ n．压紧的

vulnerable /"vʌlnərəbl/ 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。

空13

A:near B:from C:inside D:over

A Biological Clock

　　Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells   1   when to form flowers and when the flowers should open¹. It tells   2   when to leave the protective cocoons and fly away，and it tells animals and human beings when to eat, sleep and wake.
　　Events outside the plant and animal   3   the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur   4 _ the number of hours of daylight. In the short   5   of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight in summer.
　　Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration   6   twice each year. Birds   7   flying become restless when it is time for the trip,   8   they become calm again when the time of the flight has ended.
　　Scientists say they are beginning to learn which   9   of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain   10   to control the timing of some of our actions. These   11   tell a person when to   12   ，when to sleep and when to seek food . Scientists say there probably are other biological clock cells that control other body activities.
　　Dr. Moorhead is studying   13   our biological clocks affect the way we do our work². For example, most of us have great difficulty if we must often change to different work hours.

 　14   can take³ many days for a human body to accept the major change in work hours. Dr. Moorhead said industrial officials should have a better understanding of biological clocks and how they affect workers. He said   15   understanding could cut sickness and accidents at work and would help increase a factory’s production,