JIA Yong-Bin, LIU Ping, WANG Bin, WANG Cheng-guo, DENG Ming-wen
By analyzing the characteristics of underground fluid anomalies and focal mechanism solutions before Changji MS4.8 earthquake on July 20,2022,the characteristics and distribution range of underground fluid anomalies before the earthquake were summarized.The analysis shows that the underground fluid anomaly of the Changji earthquake is within 80~140 km.From the perspective of the time from the earthquake,the underground fluid anomalies before the Changji earthquake can be divided into short-term anomalies and medium-term trend background anomalies, of which short-term anomalies are the main ones.Background anomaly of the medium-term trend shows that the dynamic water level of Xin 26 Spring decreases first and then increases.The short-term and impending anomalies are manifested as the rise of static water level in Xin 04 Well, the rise of static water level in Xin 20 Well and the rise of conductivity in Xin 15 Spring.The anomaly shows an EW distribution in space.The focal mechanism solution results show that the nodal plane I strikes 81°, the dip angle is 69°, and the slip angle is 174°.The nodal plane II has a strike of 173°, an inclination of 84°, and a sliding angle of 21°.The P-axis orientation is 305°, and the T-axis orientation is 39°, indicating that Changji MS4.8 earthquake was an earthquake event under the stress of NWW compression and NEE extension.The direction of the main compressive stress obtained from the focal mechanism solution of Changji earthquake is the same as that of anomaly distribution before the earthquake.
