Analysis of the synchronous rise of water level in the Tangshan fault zone.

Since 2019, a synchronous and abnormal upward trend in water levels has been observed in the Tangshan and Majiagou observation wells, located within the Tangshan fault zone, coinciding with three earthquakes of magnitude 4.0 or higher in the Tangshan area. This study conducted a quantitative analysis of the influence of environmental factors on water level rises, based on data regarding groundwater exploitation, reservoir storage, and precipitation in the recharge areas surrounding the observation wells. The stress state of the observed aquifers was quantitatively determined, and regional stress changes were analyzed in conjunction with digital seismology and deformation observation data. The degree of water-rock interaction was evaluated using two-period testing data for ions and hydrogen and oxygen isotopes. Comprehensive analysis indicates that the recent abnormal changes in water levels at the Tangshan and Majiagou observation wells cannot be attributed solely to precipitation and surrounding environmental factors but also be associated with variations in stress fields and tectonic activity in the Tangshan area. This study shows that the vertical stress variations in the wellbore of the inversion of groundwater hydrogeological parameters and the water-rock interactions within the observation wells can to some extent reflect the changes in the regional stress field, which provides a theoretical basis for determining the seismicity by using the changes in groundwater in the future.