Remotely triggered seismic activity in Hakone volcano during and after the passage of surface waves from the 2011 M9.0 Tohoku-Oki earthquake
Remotely triggered seismic activity in Hakone volcano during and after the passage of surface waves from the 2011 M9.0 Tohoku-Oki earthquake
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2011 年 M9.0 东北冲地震的表面波通过期间和之后远程触发了箱根火山的地震活动
DOI：
10.1016/j.epsl.2013.05.004
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发表时间：
2013
影响因子：
5.3
通讯作者：
Akio Yoshida
中科院分区：
文献类型：
--
作者：
Yohei Yukutake;Masatoshi Miyazawa;Ryou Honda;Masatake Harada;Hiroshi Ito;Minoru Sakaue;Kazuki Koketsu;Akio Yoshida
2011年3月11日，日本东北大地震发生后不久，震中距离450公里的日本中部的Hakone火山下的地震活动明显增加。地震活动性的增强是在主震的大振幅表面波通过时开始的，并在随后的2个月内持续。我们获得了地震序列的震源和震源机制，目的是澄清远程触发地震活动的物理机制。我们使用的数据来自一个密集的地震网络，其中包括箱根火山及其周围的56个在线永久和离线临时站点。我们发现，在表面波通过期间发生的地震位于火山口普通地震活动的下深度极限。这些地震的震级比东北冲地震前的普通地震活动性和表面波通过后引发的地震活动性都要大。确定的震源机制为p轴向NW-SE方向的走滑断层类型，与地表波通过后的震源机制和构造应力场一致。我们还试图通过使用波形相关技术来检测表面波通过后立即发生的缺失事件。探测到的事件分布在表面波通过期间发生的地震的震源附近。面波到达后的前四次事件的发生时间与面波产生的正应力减小的阶段一致。结果表明，2011年东北大地震表面波引起的动应力变化对触发地震活动序列的启动起着重要作用。假设断层上的正应力变化确实在地震的触发中起了重要作用，我们提出断层上渗透率振荡引起的流体流动是箱根火山下后东北- oki地震发生的主要机制。
Immediately after the March 11, 2011, M9.0 Tohoku-Oki earthquake, seismic activity increased remarkably beneath Hakone volcano, central Japan, at an epicentral distance of 450km. The heightened seismicity was initiated during the passage of the large-amplitude surface waves from the main shock and continued over the subsequent 2 months. We obtained hypocenters and focal mechanisms of the seismic sequence, with the aim of clarifying the physical mechanism responsible for the remotely triggered seismicity. We used data from a dense seismic network containing 56 online permanent and offline temporary stations in and around the Hakone volcano. We found that the earthquakes that occurred during the passage of the surface waves are located at the lower depth limit of ordinary seismicity in the caldera. These earthquakes have larger magnitudes than both the ordinary seismicity prior to the Tohoku-Oki earthquake and the seismicity triggered after the passage of the surface waves. The focal mechanism that we determined is a strike–slip fault type with the P-axis in the NW–SE direction, which is consistent with the focal mechanisms of earthquakes that occurred after the passage of the surface waves and the tectonic stress field in the region. We also tried to detect missing events that occurred immediately after the passage of the surface waves, by using a waveform correlation technique. The detected events are distributed near the hypocenters of the earthquakes that occurred during the passage of the surface waves. The origin times of the first four events after the arrival of surface waves are consistent with the phases of the decrease in normal stress generated by the surface waves. The results suggest that the changes in dynamic stress due to the surface waves from the 2011 Tohoku-Oki earthquake contributed significantly to the initiation of the sequence of triggered seismic activity. Assuming that normal stress changes on the faults did play an important role in the triggering of earthquakes, we propose that fluid flow induced by the oscillation of permeability on the faults is the main mechanism for the initiation of post-Tohoku-Oki earthquakes beneath the Hakone volcano.