2021年8月26日阿克塞M_(S)5.5地震热红外亮温异常研究

ANALYSIS OF THERMAL INFRARED BRIGHTNESS TEMPERATURE ANOMALY CHARACTERISTICS BEFORE AKSAI M_(S)5.5 EARTHQUAKE ON AUGUST 26,2021

基于相对功率谱方法分析2021年8月26日阿克塞M_(S)5.5地震前红外亮温相对功率谱时空演化特征。结果表明:阿克塞M_(S)5.5地震前震中西侧出现明显亮温相对功率谱增强,增强区域沿阿尔金断裂与柴达木北缘断裂分布,持续大约1个月后消失,地震在异常消失8 d后发生。相对功率谱值呈现上升-下降-再上升-再下降的变化过程,地震在功率谱值回落之后发生。根据震例统计结果显示,2008年以来新疆地区共有15次热红外亮温异常,热红外异常出现后3个月内,在异常区周边及附近250 km范围内发生7组M_(S)≥5.0地震,且异常面积与对应地震震级存在正相关关系。

Based on the relative power spectrum method,this paper uses the FY-2G infrared remote sensing brightness temperature product to analyze the spatiotemporal evolution characteristics of the relative power spectrum of the infrared brightness temperature before Aksai M_(S)5.5 earthquake on August 26,2021.The results show that before Aksai M_(S)5.5 earthquake,there was an obvious increase in the relative power spectrum of the brightness temperature on the west side of the epicenter.The enhanced area was distributed along the Altyn fault and the northern margin of Qaidam fault,which lasted for about one month and then disappeared,and the anomaly disappeared 8 days after the earthquake occurred The relative power spectrum value presents a changing process of rising-falling-rising-rising-falling again,and the earthquake occurs after the power spectrum value falls back.Further sorting out the thermal infrared brightness temperature anomalies in Xinjiang since 2008,the statistical results show that within 3 months after the thermal infrared anomaly occurs,seven groups of earthquakes with M_(S)≥5.0 have occurred around and within 250 km of the abnormal area,and there is a positive correlation between the abnormal area and the corresponding earthquake magnitude.