青海门源MS6.9地震震前OLR异常与InSAR同震形变关联性分析

Correlation Analysis between Pre-earthquake OLR Anomaly and InSAR Coseismic Deformation of the Qinghai Menyuan MS6.9 Earthquake

摘要:

对比分析利用涡度距平法提出的2022年1月8日青海门源 M_S6.9 地震震前射出长波辐射(OLR)短期异常分布和震后InSAR技术提取的门源地震同震形变空间分布,结果显示,震前红外辐射增强区与InSAR同震破裂形变区的空间位置基本吻合,扩展形式基本相似(同震破裂形变区分布在红外辐射异常区内部)。在震前的全国范围OLR空间分布上,仅青海德令哈—西宁—甘肃武威一带出现了呈“哑铃”状近WE向展布的OLR热辐射增强区,空间可辨识度高,OLR异常时空演化过程遵循了岩石应力加载破裂过程中的热异常规律,显示热异常变化与应力变化存在关联; InSAR技术提取的同震形变同样位于肃南—祁连断裂(俄堡段)、托莱山断裂和冷龙岭断裂的交汇区。InSAR同震形变结果揭示了地表形变以水平方向为主,断层运动具有典型的走滑变形特征。InSAR同震形变结果为红外遥感反映地震形变提供可检验的地质实体监测证据,验证了门源地震前辐射增强异常是地震构造地应力强度变化的遥感物理参量反映。

Abstract:

The short-term anomalous distribution of outgoing longwave radiation(OLR)obtained before the January 8,2022 Menyuan M_S6.9 earthquake in Qinghai Province was compared with the spatial distribution of the coseismic deformation of the Menyuan earthquake extracted by the post-earthquake InSAR technique. The results show that the pre-earthquake infrared radiation enhancement area is basically consistent with the InSAR coseismic rupture deformation area,and the expansion forms are basically similar(the coseismic rupture deformation area is distributed inside the infrared radiation anomaly area). In terms of the spatial distribution of OLR nationwide before the earthquake,only the area of Delingha-Xining-Wuwei has a dumbbell-shaped OLR thermal radiation enhancement area,which is distributed in the near west-east direction,and the spatial recognizability is high. The spatiotemporal evolution process of OLR anomalies follows the thermal anomaly law during rock stress loading and fracture,suggesting that the thermal anomaly changes are related to stress changes. The coseismic deformation extracted by InSAR is mainly located in the intersection of the Sunan-Qilian fault,the Toleshan fault and the Lenglongling fault. The InSAR coseismic deformation results reveal that the surface deformation is mainly in the horizontal direction,and the fault movement has typical strike-slip deformation characteristics. InSAR coseismic deformation results provide referenced geological entity monitoring evidence for infrared remote sensing to reflect seismic deformation,and verify that the radiation enhancement anomaly before the Menyuan earthquake is a remote sensing physical parameter reflection of changes in seismic tectonic stress intensity.