阿拉伯板块持续向北挤压欧亚板块,促使阿富汗-巴基斯坦边境应力场变化、局部闭锁和破裂失稳,导致2022年6月21日发生了6.0级帕克提卡浅源地震,这是该地区近10年发生的最大地震。本文利用GCOM-W1卫星AMSR-2微波辐射计观测的微波亮温(MBT)数据,运用时空加权两步法提取了地震前后、震中周边超百万km2^范围内的MBT残差,揭示了MBT时空演变特征与正异常现象的多态性。联合降雨、土壤湿度及CH4、CO温室气体卫星观测数据,结合区域地质条件和地表覆盖类型,逐一进行了多态MBT正异常的归因辨析。研究表明：1)震中东南部印度河平原和西北部卡拉库姆沙漠显现MBT正异常,可归因于孕震应力激活的岩石空穴粒子(P-hole)从孕震区向上传递到第四系盖层,导致地表浅层介电常数降低；2)临震期高山地区显现MBT正异常,可归因于应力激活的P-hole向高山低温区传递,并聚集在砂性沉积岩盖层,致使砂性盖层微波介电常数降低；3)震中西北部沿Herat断裂带显现MBT正异常,与临震期断层拉张有关,可能受到煤系CH4、CO沿断层与矿井逸出产生的温室效应影响。本研究对于西亚地区地震微波遥感观测及地震异常识别有重要意义,对全球其他地区的地震遥感监测及异常认知也有参考价值。

The Arabian plate continues to squeeze the Eurasian plate northward, which promotes stress field changes, local stress locking and rupture instability. This resulted in the magnitude 6.0 shallow earthquake on June 21, 2022 in Paktita province on the Afghanistan-Pakistan border, which is the largest earthquake in the region in the past 10 years. It is very important to study the phenomenon and mechanism of earthquake. Through analyzing the earthquake case with multi-source data, the eternal earth science topic of earthquake perception and cognition is studied deeply. In this study, the microwave brightness temperature (MBT) data collected by the AMSR-2 radiometer of the Aqua satellite was used to extract pre-earthquake and post-earthquake MBT residuals within more than a million square kilometers around the epicenter by using spatio-temporally weighted two-step method, and reveal the spatio-temporal evolution characteristics of MBT and the polymorphism of positive MBT anomalies. Based on the data of precipitation, soil moisture, regional geological map, land cover and greenhouse gas such as CH4 and CO, the attribution analysis of positive polymorphic MBT anomalies was discriminated one by one. We reached that: 1) The positive MBT anomaly in the Indus Plain in the southeast of the epicenter and the positive MBT anomaly in the Karakum desert to the northwest of the epicenter could be attributed to the cavity particles (P-hole) activated by the seismogenic stress, transferring from the seismogenic area to the Quaternary overburden along the stress gradient, which reduce the dielectric constant of the dielectric constant in shallow surface layer; 2) The positive MBT anomaly in the alpine area during the earthquake period could be attributed to the transfer and accumulation of stress-activated P-hole to the alpine low-temperature area, which resulted in the decrease of microwave dielectric constant of the sandy layer;3) The positive MBT anomaly along the Herat Fault in the northwest of the epicenter was related to the fault stretching during the imminent earthquake, and might had been affected by the greenhouse effect caused by the degassing of coal-bearing formations along fault and coal mines. In this study, the temporal and spatial evolution of the MBT of the Paktika earthquake was analyzed. The results showed that the MBT positive anomalies was affected by many factors such as regional plate structure activity, geological lithology and surface land cover. The MBT anomaly in seismogenic stage was polymorphic, and needed to be carefully screened using multi-source information and multi-parameters. The study is of great significance for observing and identifying the seismic anomaly in West Asia, and has reference value for the seismic remote sensing monitoring and anomaly recognition in other parts of the world.