2022年云南宁蒗MS 5.5地震前云南地区异常特征分析

通过对2022年1月2日宁蒗M_S 5.5地震前震中附近地区地震学、地下流体、定点形变等观测资料进行分析，发现本次地震前多学科异常呈现以下特征： ① M_S 5.5地震发生在宁蒗地区M_S ≥ 5.0地震平静近10年背景下，震中附近M_L ≥ 3.0地震于震前1年形成空区，主震发生在空区边缘，空区长轴180 km，按照川滇地区统计公式计算，未来发生地震的震级为5.8±0.5，与宁蒗M_S 5.5地震大小相当； 2015年以来，震中附近50 km范围内M_L ≥ 3.0地震呈平静—活跃—平静—发震的特征； ②地球物理观测异常均于震前7个月内出现，集中分布在滇西北地区距震中300 km范围内，且水温和水位测项异常出现较早； ③定点形变采用NS向与EW向幅值相加来描述同一观测资料的变化，数据曲线幅值增大可作为临震异常3个月短期指标，距震中越近，观测台项异常比例越高；④大部分宏观异常出现在震前3个月内，宏观异常增多可作为时间预测判据。综合上述多学科异常，认为地震学异常出现最早，可用于判定发震区域，用流体和定点形变观测异常追踪时间，宏观异常更多作为短期判定指标，可为宁蒗地区M_S ≥ 5.0地震资料积累提供跟踪思路和方法。

Anomaly characteristics before the Ninglang MS 5.5 earthquake in 2022, Yunnan Province

By analyzing the observation data of seismology, subsurface fluid, and fixed point deformation in the area near the epicenter of the Ninglang M_S 5.5 earthquake on January 2, 2022, it is found that the multi-disciplinary anomalies before the Ninglang M_S 5.5 earthquake show the following characteristics: ① The M_S 5.5 earthquake occurred in Ninglang area under the background of M_S ≥ 5.0 earthquake quiescence for nearly 10 years. M_L ≥ 3.0 earthquakes near the epicenter formed a gap with a long axis of 180 km one year before the earthquake and the earthquake occurred at the margin of the gap. According to the statistical formula of Sichuan-Yunnan area, the magnitude of the future earthquake should be 5.8 ±0.5, which is similar to the Ninglang M_S 5.5 earthquake. Since 2015, M_L ≥ 3.0 earthquakes within 50 km of the epicenter have the characteristics of quiescence, active, quiescence; ② The geophysical anomalies all appeared within 7 months before the earthquake. They were concentrated within 300 km of the epicenter in northwest Yunnan. The water temperature and water level anomalies appeared earlier; ③ The observation of the fixed point deformation is described by the sum of the amplitude of the northsouth and east-west components. The increase of the amplitude of the data can be used as a shortterm index of three months before the earthquake. The closer to the epicenter, the higher the proportion of anomalous observation items; ④ Most of the macroscopic anomalies occurred within 3 months before the earthquake, and the increase of the macroscopic anomalies can be used as the time prediction criterion. Based on the above multidisciplinary anomalies, it is believed that the earliest occurrence of seismological anomalies can be used to determine the seismogenic area, and the tracking time of anomalies observed by fluid and fixed point deformation can be used as shortterm indicators, which can provide tracking ideas and methods for the accumulation of M_S ≥ 5.0 earthquakes in Ninglang area.