Analysis on the water level anomaly at Delingha Gahai well in Qinghai Province

For understanding the abnormal water level of Delingha Gahai well in Qinghai Province in 2018, the relevant information about the well is reviewed. The two water level instruments of the well are stable and consistent in operation. The anomalies in this period are not related to rainfall and air pressure, and the apparent stress value in vicinity of the well hole is high, which indicates that the crustal stress level in this area is further enhanced. The correlation analysis on amplitude variance of water level and first-order difference shows that the abnormal reliability is high, which reflects the regional tectonic activity information. This is a common precursor of two moderate earthquakes in its surrounding area, and belong to short-term and medium-term anomalies.