与2011年东北地震相关的承压地下水水位和温度的震前变化。

Orihara Yoshiaki, Kamogawa Masashi, Nagao Toshiyasu

Department of Physics, Tokyo Gakugei University, Japan.

Earthquake Prediction Research Center, Tokai University, Japan.

Sci Rep. 2014 Nov 4;4:6907. doi: 10.1038/srep06907.

Anomalous groundwater changes started three months before the 2011 M9.0 Off the Pacific coast of the Tohoku Earthquake (Tohoku EQ), Japan. Groundwater level and temperature decreased almost simultaneously in a 2000-m well at a spa, Goyo-onsen, in Iwate Prefecture, 155 km northwest of the epicenter. Since the source of Goyo-onsen, located above the edge of a coseismic rupture area of the Tohoku EQ fault, is probably confined, the observed anomalies were caused probably by preseismic crustal deformation. Preseismic groundwater anomalies have been observed prior to similar large subduction EQs such as the 1946 M8.1 Nankai EQ. Thus, monitoring confined groundwater may be useful to identify precursors of large subduction EQs.

异常的地下水变化在2011年日本东北地震（东北地震）发生前三个月就开始了。在震中西北155公里处岩手县的小温泉（Goyo-onsen）的一口2000米深的温泉井中，地下水位和温度几乎同时下降。由于位于东北地震断层同震破裂区域边缘上方的小温泉的水源可能是承压的，观测到的异常可能是由震前地壳变形引起的。在类似的大型俯冲地震（如1946年的南海8.1级地震）之前也观测到了震前地下水异常。因此，监测承压地下水可能有助于识别大型俯冲地震的前兆。