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Eruptions of Mount Saint Helens
On March 27, the US Government scientists made a decision after they predicted the eruption of Mount Saint Helens. They telephoned all state and local officials in the area and told them that a serious eruption was possible at any time. Roads were closed to every one except scientists and forest keepers struggled to keep curious visitors away from the mountain.
Shortly afternoon on March 27, Mount Saint Helens erupted for the first time in 123 years.
People living north of the mountain heard a loud boom that shook their windows, and airline pilots flying near the volcano soon afterwards described a thick black column of ash and steam shooting more than 2,100 meters into the sky.
Later, scientists found that the explosion had made a new crater (大坑) in the top of the mountain, not far from the old crater. The north side of the peak now had a huge bulge (凸出部分)where rock and ice had been pushed out by the eruption.
A second eruption shook the mountain on March 28. It, too, sent up a column of black ash high into the sky. By March 29, scientists flying over the mountain saw that a second crater formed about 9 meters from the first one. Strange blue flames flickered (闪烁) inside the crater and sometimes jumped from one crater to the other.
By April the mountain had erupted several more times and the snow on the north slope of the peak was black with ash. Ash carried by the wind had fallen on towns as far as 240 kilometers away from Mount Saint Helens.
During the first week of April, Mount Saint Helens gave scientists something new to worry about: harmonic tremors (振动) recorded by scientists showed a big eruption would happen. All during April and into May Mount Saint Helens continued to shudder (振动 ) and shoot out ash. By April 8, two craters had merged to from a vast hole nearly a half of a kilometer wide and 250 meters deep.
Scientists&39; main worry during this time was the growing bulge of rock and ice on. the north face of the mountain. By May 7 scientists feared the worst. Their warnings led Washington Governor to set up safety zones around the mountain. The inner "red" zone was open to scientists only. The outer "blue" zone was open only to people who got special permits. But in spite of these warnings, some people got past the road barriers and risked their lives trying to get close to the volcano.
American scientists predicted that Mount Saint Helens was to erupt soon. 查看材料
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