Abstract: Coseismic responses of water level and temperature in 6 wells of Jinshajiang groundwater observation network to the Japan M_S9.0 earthquake are presented, and response characteristics and mechanism are analyzed. The analytical results show that ① Whether or not there is water level response depends to a large extent on the height of water pillars in a well, and there are coseismic responses of water level in 4 wells with oscillation pattern, but the beginning time, extent and the continued time of oscillation is different in different wells, and these differences depends chiefly on the transmissibility coefficient of the well-aquifer system; ②③There are coseismic responses of water temperature in 3 wells with response pattern of non-symmetry “V” or “U” forms, and front drop is related with the mix of upper water(with high temperature)and lower water(with lower temperature)in a well,the rise in later stage is related with the conduction of heat between water in wells and rock outside the well, and the extent of drop or rise of temperature and continued time are different for different wells, these difference depends probably on water gradient in well and heat conduction capability of water-rock system; and the extent of temperature change in later rise is always larger than that in front drop, probably related to the increase of geothermal flow caused by seismic wave effects。

Key words: Groundwater level, Groundwater temperature, Coseismic response, Jishajiang groundwater observation network, Japan M_S9.0 earthquake