2011年日本M_W9.0地震引起的环渤海地区井水温度变化分析

Responses of Water Temperature in Wells around Bohai Area to the 2011 Japan M_W9.0 Earthquake

2011年3月11日的日本MW9.0地震在中国引起了大范围的井水温度同震变化,而水温震后持续变化的井孔多数分布在井网密度较大、距震中较近的环渤海地区。本文分析了环渤海地区水温震后变化的特征和机理。结果表明,水温震后变化形态为上升,变幅0.005～0.976℃,空间分布在同震位移较大、张性应变较明显和地震能量密度较大的区域;依据同井水位资料,一些井孔的水温和水位震后变化特征较一致,其水温震后升高可能是地震波增大含水层渗透性的结果;另一些井孔的水位震后变化不显著,其水温震后升高可能与地震波增大井区大地热流有关。

The coseismic responses of water temperature to Mw9. 0 earthquake have been recorded all over China, while the post-seismic responses mainly concentrate in the area a- round Bohai. This area has more water temperature monitoring wells and is relatively clos- er to the earthquake. This area is also located in regions of volumetric expansion and larger GPS eoseismic displacements caused by the earthquake. The paper analyzes the character- istics and mechanisms of water temperature post-seismic responses around Bohai Sea area. The results show that the characteristics of the post-seismic responses are all rising, and their amplitudes are in the range of 0. 005-0. 976℃. By analyzing water level post-seismic responses in the same wells, two possible mechanisms are proposed for explaining the wa- ter temperature post-seismic responses. One is that seismic waves increase aquifer permea- bility to account for the wells with the same rhythm of water level and temperature post- seismic responses. The other is that seismic waves increase heat flow to account for the wells that do not have water level post-seismic responses.