mi·cro·seism /ˈmaɪkrəˌsaɪzəm/
  微弱的地殼震動
  Mi·cro·seism n.   A feeble earth tremor not directly perceptible, but detected only by means of specially constructed apparatus. -- Mi*cro*seis*mic Mi*cro*seis*mic*al a.
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  microseism
       n : a small earthquake [syn: tremor, earth tremor]