The influence of groundwater mining on regional seismicity in the North China Plain

As a strong earthquake area in mainland China, the North China Plain (NCP) is also the most populous plain in China. Since the 1960s, this area has experienced large-scale groundwater mining. Based on the groundwater level change in NCP from 1959 to 2016, combined with the regional geological background, we established a pore elasticity model to quantitatively analyze the influence of groundwater mining on regional seismic activity. The results show that the groundwater unloading leads to crustal uplift, with a maximum of about 35 mm. And extensional stress changes in the vertical direction upto 92 kPa at a depth of 10 km. The results of the Coulomb stress changes calculated by the focal parameters of historical earthquakes in NCP show that elastic unloading increases the normal stress on the fault plane, but the decrease of pore pressure makes the Coulomb stress changes negative in the mining area, while the results are positive outside the mining area. Through the analysis, the results of Coulomb stress changes are affected by the fault parameters and location, the groundwater mining in NCP reduces the risk of great earthquakes. However, with the slowdown of the mining rate and the possible groundwater level rise in the future, it will further affect the regional seismic activity.