Abstract: 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.

Key words: Water temperature, Water level, Post-earthquake response, the 2011 Japan M_w9.0 earthquake