Analysis of Anomalous Characteristics Before Ninglang Ms5.5 Earthquake on January 2,2022
In order to provide the reference for judging the destructive Ninglang earthquake anomaly and tracing the earthquake situation in the future,the characteristics of seismicity anomaly of the January 2th Ninglang Ms5.5 earthquake and the precursory data within 250 km from the epicenter are analyzed and summarized,and the anomalies before the two historical M≥5 earthquakes within 50 km of the epicenter are compared and analyzed.The results show that there are 16 anomalies before the Ninglang Ms5.5 earthquake,including 5 seismicity anomalies,9 micro-precursory anomalies and 2 macro-precursory anomalies,and there are certain characteristics in time and space.In time,the micro-precursory anomalies are mainly short-term anomaly;the number of anomalies increases obviously 3 months before the earthquake;the anomalies are mainly annual variation change and transition;and the anomalies of seismicity are mainly long-term earthquake quiescence.In spacce,the micro-precursory anomalies are mainly concentrated with-in 200 km of the epicenter;and the seismicity anomalies are mainly distributed in bands of small earth-quakes.The anomaly features common to the historical earthquakes are as follows:the Ninglang-Muli-Yanyuan multi-earthquake area has a long period of moderate and strong earthquakes that are remarkably calm,and the short imminent fluid anomaly is prominent under the background of the long trend of deforma-tion breaking the annual variation anomaly.