2011年日本9.0级地震的同震位错以及震后应力松弛过程对中国大陆的影响

本文基于日本GEONET的GPS观测资料, 对日本2011年9.0级地震的同震和震后形变过程进行了研究。 结果表明, 日本9.0级地震使中国大陆出现了显著的同震位移, 几乎对整个中国大陆都有影响。 位移量在中国东北地区最大, 接近甚至超过该地区的年运动速率。 震后1年观测到的形变基本上可由沿着断层面的蠕滑进行模拟, 粘弹松弛的贡献不大。 根据所得到的震后蠕滑模型, 震后1年形变所释放的能量等同于发生一个8.7级地震, 其影响主要在东部地区, 最大位移约为年运动速率的30%。 预测在未来2年, 该地震的影响范围将逐渐减小。 地震造成的粘弹松弛在未来50~100年的尺度上, 对东北地区有拉张效应。 日本9.0级地震整体上起到了卸载中国大陆在板块间挤压过程中所累积应变能的作用, 因此该地震发生后的几个月, 中国大陆东部的地震活动水平较震前明显降低。

Coseismic Slip and Post-seismic Relaxation of the 2011 M9.0 Tohoku-oki Earthquake and its Influence on China Mainland

Based on GPS measurements of GEONET in Japan, we investigated the coseismic slip and postseismic relaxation of the 2011 M9.0 Tohoku-oki earthquake, and analyzed its influence on China mainland. The results indicate that the Tohoku-oki earthquake produced significant coseismic displacement in China mainland, especially in Northeast China, where the displacements are comparable or even higher than the annual tectonic motion. The observed displacements of 1 year following the Tohoku-oki earthquake can be generally modeled by creep on the fault plane. The post-seismic relaxation in 1 year following this big event releases the strain energy equivalent to an earthquake of M8.7, and mainly imposes influence in eastern China. Its produced displacements reach 30% of the annual tectonic motion. Furthermore, we predict that the influence of the Tohoku-oki earthquake in China will shrink quickly in the next 2 years. The viscoelastic relaxation in the deep depth has a significant influence in a long-term and at a large spatial scale, and has an extension effect in the northeast part of China for 50~100 years. The Tohoku-oki earthquake broke the locked segment of hundreds of kilometers between Eurasian and Pacific plate, and unloaded the stress in China mainland that accumulated by tectonic loading. Therefore, seismic activity in China after the Tohoku-oki earthquake is lower comparing to the seismic level before the earthquake.