Discriminating the polymorphism and attribution of microwave radiation anomalies related to the June 2022 Mw 6.0 Paktita earthquake in Afghanistan
The Arabian plate continues to squeeze the Eurasian plate northward,which promotes stress field changes,local stress locking,and rupture instability.This phenomenon 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.Studying the phenomenon and mechanism of earthquakes is crucial.By analyzing an earthquake case with multisource 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 postearthquake MBT residuals within more than a million square kilometers around the epicenter by using a spatiotemporally weighted two-step method,revealing the spatiotemporal evolution characteristics of MBT and the polymorphism of positive MBT anomalies.On the basis of the data of precipitation,soil moisture,regional geological map,land cover,and greenhouse gases,such as CH4 and CO,the attribution analysis of positive polymorphic MBT anomalies was discriminated one by one.We found that(1)the positive MBT anomaly in the Indus Plain,southeast of the epicenter,and the positive MBT anomaly in the Karakum desert,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 reduces 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 in the microwave dielectric constant of the sandy layer;(3)the positive MBT anomaly along the Herat Fault,northwest of the epicenter,was related to the fault stretching during the imminent earthquake and might have 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.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 must be carefully screened using multisource information and multiparameters.This study is crucial for observing and identifying the seismic anomaly in West Asia and has reference value for seismic remote sensing monitoring and anomaly recognition in other parts of the world.
remote sensingmicrowave brightness temperatureSeismic anomalyP-holemicrowave dielectricgreenhouse effectcrustal stress field alteration
万方数据
维普
