Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan
Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan
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DOI：
10.1186/s40623-016-0590-2
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发表时间：
2017-01-03
影响因子：
3
通讯作者：
Shimizu, Hiroshi
中科院分区：
文献类型：
--
作者：
Aizawa, Koki;Asaue, Hisafumi;Shimizu, Hiroshi
2016年4月16日日本标准时间1时25分发生的熊本M-JMA 7.3级地震，不仅在震中附近引发了余震，还在距离主震震中50-100公里的地方引发了地震。地震活动可分为三个区域：（1）主断层附近，（2）阿索火山北方区域（震中东北50 km），（3）由府、鹤见、伽蓝三座火山周围（震中东北100 km）。值得注意的是，这些区域之间的区域明显不活跃。通过对247个宽频带（0.005 ~ 3000 s）大地电磁和大地电磁观测点的一维电阻率结构分析，明确地表明地震发生在与导电带或导电-导电过渡带相邻的电阻率区。相比之下，地震活动是相当低的导电带，这被解释为连接流体的区域。我们认为，一系列的地震是由当地积累的应力和/或流体供应的导电带。由于地震和电阻率结构之间的关系与以前的研究是一致的，地震危险性评估通常可以通过考虑电阻率结构来改进。根据2016年熊本地震系列，我们认为沿着MTL的西部延伸，有两个区域具有相对较高的地震生成潜力。
The M-JMA 7.3 Kumamoto earthquake that occurred at 1: 25 JST on April 16, 2016, not only triggered aftershocks in the vicinity of the epicenter, but also triggered earthquakes that were 50-100 km away from the epicenter of the main shock. The active seismicity can be divided into three regions: (1) the vicinity of the main faults, (2) the northern region of Aso volcano (50 km northeast of the mainshock epicenter), and (3) the regions around three volcanoes, Yufu, Tsurumi, and Garan (100 km northeast of the mainshock epicenter). Notably, the zones between these regions are distinctively seismically inactive. The electric resistivity structure estimated from one-dimensional analysis of the 247 broadband (0.005-3000 s) magnetotelluric and telluric observation sites clearly shows that the earthquakes occurred in resistive regions adjacent to conductive zones or resistive-conductive transition zones. In contrast, seismicity is quite low in electrically conductive zones, which are interpreted as regions of connected fluids. We suggest that the series of the earthquakes was induced by a local accumulated stress and/or fluid supply from conductive zones. Because the relationship between the earthquakes and the resistivity structure is consistent with previous studies, seismic hazard assessment generally can be improved by taking into account the resistivity structure. Following on from the 2016 Kumamoto earthquake series, we suggest that there are two zones that have a relatively high potential of earthquake generation along the western extension of the MTL.