2011年日本Mw9.0地震引起的环渤海地区井水温度变化分析

2011年3月11日的日本M_w9.0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°C,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。

Responses of Water Temperature in Wells around Bohai Area to the 2011 Japan Mw9.0 Earthquake .

The coseismic responses of water temperature to M_w9.0 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 lar ger GPS coseismic displacements caused by the earthquake. The paper analyzes the charac teristics and mechanisms of water temperature post-seismic responses around Bohai Sea ar ea. 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°C. By analyzing water level post seismic responses in the same wells, two possi ble mechanisms are proposed for explaining the water temperature post seismic responses. One is that seismic waves increase aquifer permeability 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 postseismic responses.