远场地震在台湾南部的触发非火山型微震颤

Remote triggering of non-volcanic tremor in southern Taiwan

  • 摘要: 选取2011—2016年发生的38次震中距大于1 000 km的MW≥7.5地震震后3小时的连续波形资料,利用人工检视方法对这38次地震是否触发了我国台湾地区的非火山型微震颤进行了调查。分析结果显示:这38次地震中有4次远震触发了非火山型微震颤,事件持续300—500 s不等。利用网格搜寻方法对此4次微震颤事件进行了定位,确定震中位于台湾中央山脉南段,震源深度为21—53 km。结合研究区内地球物理观测资料,分析认为是由于远震产生的面波改变了研究区内的瞬时应力,进而导致断层蠕滑触发了微震颤事件。

     

    Abstract: We selected three-hour continuous waveforms after 38 MW≥7.5 earthquakes with epicentral distance larger than 1 000 km during 2011 to 2016 in Taiwan region of China to investigate whether it has triggered non-volcanic tremors (NVTs) by using visual identification. Out of the 38 earthquakes, we identified four teleseismic events which triggered NVTs with duration ranging from 300 s to 500 s. Using grid search, four tremor sources were located in the southern Central Range in Taiwan and the focal depth ranges from 21 to 53 km. Based on the local geophysical observation data, we proposed that the transient stress change induced by surface wave of large teleseisms could lead to the fault creep, which is the critical factor for tremor generation.

     

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