刚看到新闻说,温哥华岛外的14英里的海底发生地震。
科学分析认为,附近一个巨大的断层(实际为板块交界循环处)将剧烈错位,并引发可能高达30米的海啸。
具体机制详见下图。对于地球板块来说,这将只是一个很小的调整,但其对沿海的人们来说,后果严重。
April 25, 2011 – PORTLAND – The north-west coast of the U.S. could be devastated by a huge movement of undersea plates known as a ‘megathrust’ earthquake, scientists say. A review of the dangers posed by the Juan de Fuca plate released in the wake of the Japanese quake has raised fears that the Pacific seaboard could be similarly ravaged. Professor Chris Goldfinger, director of the Laboratory at Oregon State University, told the newspaper that their information showed an increase in pressure at the plates: ‘It’s loading a spring for a future earthquake, there’s no doubt about that.’ And geologist Jeffrey Park, director of the Yale Institute for Biospheric Studies, said in a recent – separate – article: ‘History tells us that more mega-thrust earthquakes could occur in the next decade, but we have no evidence that the recent rate of nearly one mega-thrust per year will persist for longer than that.’ Cascadia, which stretches from Vancouver island to northern California, has been dormant for over 300 years but scientists now believe there is a 45 per cent probability of an earthquake of an 8.0 magnitude or higher in the next 50 years. They add there is a 15 per cent chance of magnitude 9 or more. Such a quake could produce a massive tsunami and engulf the Pacific Northwest coast, affecting Oregon, Washington state and Vancouver Island, according to The Times, with a tsunami with waves of up to 30metres high and potentially reaching Japan.
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