Analysis of near-field geophysical anomalies before the 2011 Tengchong MS 5.2 earthquake
On June 20 and August 9,2011,the Tengchong area in Yunnan Province experienced two MS 5.2 earthquakes,forming the Tengchong MS 5.2 double earthquakes.Before the two Tengchong MS 5.2 earthquakes,geophysical anomalies were concentrated in the near-field area within 100 km of the epicenter.A comprehensive analysis of geophysical observation data such as water level,deformation(horizontal pendulum observation),water radon,water temperature,and flow in the near-field area of the two earthquakes revealed that:① most anomalies lasted for more than 3 months,and some began in early 2010.The significant mid-term anomaly measurement items were the water level of the Dian 19 well and the horizontal pendulum tilt observation in Tengchong;② Two months before the two earthquakes,there was a high-value anomaly in the water radon measurement item at Longling Bangla Zhang;③ During the pre-earthquake stage,before the Tengchong MS 5.2 earthquake on June 20,there were obvious macroscopic anomalies in the Tengchong Hehuatang and Rehai Dagunguo.The intensity and frequency of the anomalies significantly increased after the earthquake,which has a clear indicative significance for the Tengchong MS 5.2 earthquake on August 9.It is worth noting that within a range of 85 km from the epicenter,the Yingjiang MS 5.8 earthquake occurred on March 10,2011.The mid-term anomalies of the two Tengchong earthquakes became the"common geophysical anomaly"of this Yingjiang earthquake,and some anomalies persisted after the earthquake,with new anomalies appearing,showing characteristics that match the abnormal spatiotemporal evolution process with seismic activity migration.
Tengchong MS 5.2 earthquakegeophysical observation datashort-term anomalymacroscopic anomaly
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