Earthquak Termel Anomalies Detection Based On MODIS Data And STL Decomposition

Seismic activity in my country has the characteristics of wide spatial distribution,high earthquake occurrence rate,high earthquake intensity,and relatively shallow source.Among the various natural disasters in my country,countless people have died due to earthquake disasters,and the earthquake disasters encountered are more serious.Therefore,the in-depth study of earthquake precursors is beneficial to reduce the risk of earthquake disasters.This study uses the LST data of MODIS,the seismic thermal anomaly extraction algorithm based on the STL decomposition method and GESD inspection,and takes the temporal and spatial changes of the anomalous area around the epicenter as the main parameter.The area around the epicenter of the Shishi,Kuqa,and Wenchuan earthquakes was used as the research object,and the seismic thermal anomaly information(magnitude 3.6 or higher)of 15 earthquakes in inland China from 2003 to 2019 was extracted.Arranging and analyzing parameters such as the coverage rate of anomalous areas near the epicenter and the spatial changes of thermal infrared anomalies,the following conclusions were finally reached:(1)On the basis of the LST spatio-temporal data set,the first application of the STL decomposition method and the thermal infrared extraction algorithm of GESD inspection can effectively extract the seismic thermal anomaly information.It is found that the selected earthquake cases have obvious thermal infrared anomalies,indicating that this method is effective Earthquake-related thermal anomaly monitoring has certain reference value.(2)According to the analysis of different earthquake cases in the same region,it can be seen that the location of earthquake thermal anomalies is not stable.The evolution process of earthquake thermal anomalies near the epicenter of the five earthquake cases selected in Yutian County,Xinjiang shows that these earthquakes in Yutian County In the sub-shock cases,anomalies appeared in the northwest of the study area.The evolution process of seismic thermal anomalies near the epicenter of the four earthquake cases selected by Jinghe County,Xinjiang shows that in these few earthquake cases in Jinghe County,anomalies appeared in the southeast of the study area.The evolution process of seismic thermal anomalies near the epicenter of the three earthquake cases selected by Kuqa City in Xinjiang shows that there were anomalies in the northwestern part of the study area in these few earthquake cases in Kuqa City.(3)The occurrence time and proportion of the largest anomalous area coverage of different earthquake cases are also different.The coverage of anomalous areas near the epicenter of the five earthquakes selected by Yutian County,Xinjiang 3months before the earthquake can be seen.A total of four earthquakes reached the highest anomalous area coverage about 2 months before the earthquake.The coverage rate of anomalous areas reached its maximum 2 days before the earthquake.Among the four earthquake cases selected by Jinghe County,Xinjiang,two earthquakes reached the maximum anomalous area coverage about 2 months ago,and the anomalous area coverage reached the maximum about 2 and a half months before the mid-earthquake.The coverage rate of anomalous areas reached its maximum on the day of an earthquake.Among the two earthquake cases selected by Jiashi County,Xinjiang,the anomalous area coverage after the Ms6.5 earthquake on February 24,2003 reached the maximum of 31.1%.The coverage rate of anomalous area in the month before the Ms5.4 earthquake on October 16,2018 reached 0.1%,and it was 0on the remaining days.In the three earthquake cases selected by Kuqa City,Xinjiang,the coverage of anomalous areas reached the maximum about one month before the three earthquakes.In Wenchuan,Sichuan,the coverage rate of the abnormal area reached the maximum about 3 months before the earthquake,at 17.7%.(4)Among the 15 selected earthquake cases with a magnitude of 3.6 or higher,3 were 3.6?Ms<4.0,3 were 4.0?Ms<5.0,3 were 5.0?Ms<6.0,and 6?Ms<7.0There were 3 earthquakes and 3 earthquakes with Ms?7.0.Using an anomaly extraction algorithm based on STL decomposition and GESD inspection,the anomaly of the surface temperature before the earthquake was analyzed.For the five different research areas selected in this paper,the surface temperature anomalies before earthquakes occurred in Xinjiang Yutian and Wenchuan earthquakes are more obvious.It can be seen that the surface temperature anomaly detection based on STL decomposition and GESD inspection has a certain degree Regional adaptability.It can be seen from the monitoring results of 15 earthquake cases that there is no obvious earthquake anomaly in the three earthquake cases between 3.6?Ms<4.0,and the three earthquake cases with magnitude 7.0 all have obvious earthquake anomalies.According to the research results,it can be considered that there is a certain relationship between the magnitude of the earthquake and the anomaly of the surface temperature,and the large anomaly of the magnitude is more obvious.