Abstract:The dynamic characteristics of water temperature at different observation points are various due to the difference in observation environment, wellbore conditions, structural conditions of observation site, medium conditions, and ground hydrodynamic conditions. The water temperature at different layers of the same observation well often show different co-seismic responses due to the difference in the installation depth of water temperature sensor and the distribution of wellbore heat source. In this paper, the wavelet transform algorithm was used to analyze the co-seismic response changes of water temperature at different depths of the well in Sanhai Village, Fangxian County during three earthquakes. Combined with the well temperature gradient, the surrounding rock characteristics, and the aquifers distribution, a simple well-aquifer model was proposed. Furthermore, the dynamic mechanism of different changes in water temperature at different layers of the same well was discussed, and it is preliminarily believed that the dynamic mechanism is derived from the change caused by thermal convection from water flow.