2016年3月21日甘肃金塔4.7级地震热红外亮温异常分析

Analysis of Thermal Infrared Anomaly in Gansu JingtaMS4.7 Earthquake on March 21, 2016

摘要:

使用中国静止气象卫星FY-2E/G红外遥感亮温产品为基础数据，针对2016年3月21日甘肃金塔4.7级地震前后出现在震中区附近的显著热红外异常，运用小波变换和相对功率谱法进行异常提取和资料分析，结果表明，地震热红外异常范围主要分布在震中以北的大范围区域，震前10天左右出现功率谱增强现象，随着时间推移，异常范围逐渐向北扩大，一直持续到震时，震后14天异常开始收缩并减弱。通过对比同地区相似震例发现，本次地震与2012年5月3日金塔5.4级地震的热异常特征有许多共同点，其中相同的特征周期可为热红外地震前兆特征的归纳提供典型的参考信息，同时可为建立区域热异常统计模型积累可靠的判定依据。

Abstract:

Aim at the thermal infrared anomaly in Gansu Jingta MS4.7 earthquake on March 21, 2016, this paper collected the infrared remote sensing brightness temperature data of China Geostationary Meteorological satellite FY-2E/G, and analyzed the data by using wavelet transform and relative power spectrum transform method. The results showed that the thermal infrared anomaly was distributed in the north area of epicenter, and the power spectrum enhanced 10 days before the earthquake. With the passage of time, the anomaly range gradually expanded northward until the occurring of the earthquake, which shank and weakened 14 days after the earthquake. The spatial distribution of thermal anomaly showed a strip intersection of north-south and North East direction, which is consistent with the previous statistics results. The thermal anomaly duration of this earthquake is only about 20 days, and its characteristic period is 21 days. By comparison with the similar case in this area, we found that the thermal infrared characteristics of this earthquake had some common points with that of Jingta MS5.4 earthquake on May 3, 2012, which mainly manifested in the following three aspects:(1) there was prominent thermal reaction before the two earthquakes; (2) the characteristic periods of the two earthquakes were both 21 days, but due to the impact of the earthquake magnitude, their thermal anomaly duration was slightly different; (3) the epicenters were both located near the fault which is at the edge of the anomaly concentrated area, or the intersection of the two thermal strips. The same characteristic periods can provide reference information for the induction of thermal infrared seismic precursor characteristics, and can also provide a reliable basis for the establishment of statistical model of regional thermal anomaly. The difference of the two cases mainly manifested in the maximum peak and anomaly range. These two earthquakes were from the same area, thereby reducing the effect caused by the different geological conditions, coupled with the similar occurrence time which reduced the interference caused by climate factors, so the different magnitude is the main reason for the difference of maximum peak and anomaly range.