A small persistent locked area associated with the 2011 Mw9.0 Tohoku-Oki earthquake, deduced from GPS data
A small persistent locked area associated with the 2011 Mw9.0 Tohoku-Oki earthquake, deduced from GPS data
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根据 GPS 数据推断出与 2011 年 Mw9.0 Tohoku-Oki 地震相关的小型持续锁定区域
DOI：
10.1029/2012jb009335
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
and M. Ando
中科院分区：
文献类型：
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作者：
Ikuta;R.;M. Satomura;A. Fujita;S. Shimada;and M. Ando
根据GPS地球观测网（GEONET）测量的地表三维位移，对2011年东北冲地震的同震断层滑动分布和震前的震间耦合进行了估算。推断出的同震滑动在震中附近高达30米，在沿着日本海沟延伸的400 × 200 km区域内大于5米。滑动的力矩大小估计为Mw9.0。大于10米的同震滑动区域与四个先前已知的M7级凹凸体重叠。我们使用每日GPS数据研究了地震前15年断层上的板间耦合。我们确定，板块边界至少在过去15年中被锁定在一个几十公里的有限区域内，大约与最大的同震滑动区域相吻合，这表明这个小区域一直被锁定，最后一个补丁的破裂在导致大逆冲地震中发挥了重要作用。在过去80年中，一项使用地震波分析的研究报告了该地区M7级地震的地震滑动与滑动亏损积累的比率，这一低地震耦合可以通过该锁定区域的影响来解释，该锁定区域可能拖曳了上盘并抑制了周围地区的有效滑动亏损。
Co‐seismic fault slip distributions of the 2011 Tohoku‐Oki earthquake and inter‐seismic couplings prior to the earthquake were estimated from surface 3‐dimensional displacements measured by the GPS Earth Observation Network (GEONET). The deduced co‐seismic slip was up to 30 m near the epicenter, and greater than 5 m in a 400 × 200‐km region extending along the Japan Trench. The moment magnitude of the slip was estimated to beMw9.0. The area of co‐seismic slip greater than 10 m overlaps with four previously known M7‐class asperities. We researched inter‐plate coupling on the fault for 15 years prior to the earthquake using daily GPS data. We determined that the plate boundary was locked during at least the last 15 years in a limited area of a few 10 s of km, approximately coinciding with the maximum co‐seismic slip area, suggesting that this small area had been persistently locked and that the rupture of this last patch played an important role to cause the mega‐thrust earthquake. The low seismic‐coupling which is ratio of seismic slip to slip deficit accumulation of M7‐class earthquakes in this area, which were reported by a study using seismic wave analysis over the past 80 years, can be explained by the influence of this locked area which may have dragged the hanging wall and suppressed the effective slip deficit in surrounding area.