托福培训学校-环球托福[环球教育旗下品牌]

托福听力材料之圣海伦斯火山

2014-06-19 09:58| 来源:环球托福

摘要: 环球托福为各大考生带来托福听力材料之圣海伦斯火山,希望对考生们带来帮助。
上海环球托福培训班
Mount St. Helens vented a new column of steam October 10, a lazy plume that rose out of the crater of the snow-dusted volcano.
  The billow of steam rose from an area where a large upwelling or bulge of rock has been growing on the dome-shaped formation of rock in the crater. The plume rose several hundred feet above the 8,364-foot volcano, and light wind slowly blew it toward the south and southeast.
  The venting reminded scientists of the volcano's activity 20 years ago, when it built the dome following its catastrophic 1980 eruption.
  "It's a view very, very reminiscent of the years in the 1980s during dome-building and a few years after when the system was hot and water was being heated and vapor was rising and steam clouds were forming," said Willie Scott, a geologist with the U.S. Geological Survey.
  The plume appeared to be mostly steam, and scientists said any volcanic ash that was included was probably from past eruptions during the 1980s.
  Scott described the emission as a "very lazy conductive rise of this warm, moist air," unlike previous weeks' bursts characterized by more vigorous jetting that threw up ash, large pieces of rock and glacier ice.
  The steam emission followed an increase in earthquake activity over the previous two days, with quakes of magnitude 2.4 occurring every two minutes until Sunday, when the vibrations were more frequent but weakened to magnitude 1 or less.
  "What has been peculiar about these earthquakes is that there seems to be a disproportionate number of them that are uniform in size," said seismologist Tony Qamar at the University of Washington's seismic lab in Seattle.
  It indicates that pressure in the system is very uniform, which may suggest magma is constantly moving upward, he said. "The pressure will build up, the rock will break, and then you'll get an earthquake," Qamar said.
  Geologists do not anticipate anything similar to the May 18, 1980, blast that killed 57 people, blew 1,300 feet off the top of the peak.
  中文:
  10月10日,一股蒸汽从圣海伦斯火山口喷发出来,这缕烟从白雪覆盖的火山口缓缓升起。
  火山口的圆顶状岩石已经逐渐上涌或凸起,翻滚的蒸汽从这里升起。这座8364英尺高的火山上方升起高达几百英尺的烟柱,微风把它缓缓吹向南方和东南方向。
  这次喷射使科学家想起了圣海伦斯火山20年前的那次大爆发,自1980年那场灾难性的火山爆发后,圣海伦斯火山口形成了现在的圆顶状。
  美国地质调查局的地质学家威利·斯科特说:“这很容易让人回忆起上世纪80年代的情景,火山喷发后形成了圆顶状火山口,在这之前的几年中,整座火山都是滚烫的,水被加热后不断升起水蒸气,形成云。这个过程持续了几年,然后火山爆发了。”
  科学家说,烟柱看上去主要是由水蒸汽组成的,其中含有的火山灰很可能是80年代火山爆发的残余物。
  斯科特把这次喷发形容为“一束缓缓升起的湿热空气”,不像前几周的喷发那么有力。前几周火山喷发时,从火山口喷射出大量的火山灰,巨大的岩石和冰川的冰块。
  在过去的两天里,地震变得频繁起来,随之而来的就是水蒸气的喷发。每隔两分钟就发生一次里氏2.4级的地震,直到周日,地震变得更频繁了,但震级已降至1级或1级以下。
  华盛顿大学西雅图地震研究室的地震学家托尼·卡马尔说:“这些地震的特别之处在于它们在规模上一致,数量上却不成比例。”
  这预示着火山内部的压力非常均匀,这也就意味着岩浆在不断上涌。卡马尔说:“压力在不断增大,岩石开始迸裂,然后就发生地震了。”
  地质学家不希望发生任何与1980年5月18日那场火山爆发同样的情形。那次火山爆发导致57人死亡,整个圣海伦斯火山的高度降低了1300英尺。
  相关词汇:
  plume: an upwelling of molten material from the earth's mantle (地柱从地幔隆起的一段熔化物)
  reminiscent: tending to recall or suggest something in the past (使人联想的)