Satellite based detection of pre-earthquake thermal anomaly, co-seismic deformation, and source parameter modelling of past earthquakes

Abstract

Plate tectonics is the main action by which various endothermic and exothermic processes occurs in and on the earth, continuously changing physical form of earth’s surface. Different type of plate margins give rises to the various phenomenon like earthquake activities, volcanoes, lava eruption, mountain buildings. All these natural phenomenon has direct or indirect effect on the human’s life and the surrounding environment. Both intraplate and interplate earthquakes were recorded in human’s history. Generally, divergent and transform plate margins have shallow earthquake having small to medium magnitude whereas convergent plate margins are the primary source of high magnitude earthquake and volcanic activity. As per the recorded seismology history, intraplate earthquake of high magnitude earthquake occurred however the occurrence of these earthquakes is less as compared to the interplate earthquake. Before the advancement of the remote sensing, all seismological studies were based on the in-field measurements. With the technology revolutions, remote sensing satellites are now equipped for recording the various geophysical parameters for the study of the earthquake. The main purpose of the earthquake studies are to minimize its effect on the human life and infrastructure along with understanding the mechanism of the earthquake process. Additionally, these studies focused on the prediction of the earthquake in terms of position, time, and magnitude using the various earthquake precursors. The presented study involves satellite-based detection of pre-earthquake transient thermal anomaly and estimating coseismic deformation using InSAR (SAR Interferometry) observations of the three major earthquakes that occurred recently. The first one is Iran- Iraq border earthquake occurred on 12th November 2017 having Mw 7.3 magnitude. Near the earthquake’s epicentre, a rise of 4–6 °C from the normal temperature in both day and night Land Surface Temperature (LST) maps along the west and SW part of the fault was observed. Further, Sentinel-1A microwave satellite SAR data employing InSAR technique have been used to estimate co-seismic ground deformation for both ascending and descending pass. the highest upliftment is about 900 mm in NW side whereas subsidence of about -360 mm in SW side of epicentre are estimated. The inversion analysis reveals various source parameters giving insight about fault geometry and slip distribution. The iv results show that the event occurred due to blind reverse fault mechanism dipping NE with shallow dip. The weightage of strike slip component and dip slip component is more or less equal to each other in total slip distribution for Iran-Iraq border earthquake. Further, using these source parameters, the Coulomb statics stress calculates the unruptured stress energy zones having probability of the future seismic activity. The SW, NW and NE side of the epicentre are found to be high stress zones of approximately 3 bar as estimated from the Coulomb static stress. The aftershocks of the event are plotted and their epicentre distribution is majorly in SW and SE side of epicentre as indicate by the Coulomb static stress. Estimated total seismic moment of 1.06×1027 dyne-cm corresponding to Mw 7.32. The second earthquake is New Mirpur, Pakistan earthquake occurred on 24th September 2019 with Mw 5.4. A rise of 3–5 °C from normal temperature in both day and night LST maps around the SW, and NW side of the epicentre is observed. The InSAR results show the estimated upliftment of about 170 mm in WSW whereas maximum subsidence of about -144 mm in north side of epicentre. According to the inversion analysis, the earthquake occurred by reverse fault mechanism, with blind fault with a shallow dip trending along NW-SE. The total slip was dominated by a strike-slip component of about 0.7 meters, compared to a dip-slip component of approximately 0.4 meters. Further, SSW, NW, and north of the epicentre are high stress zones having 0.02-0.03 bars as estimated by the Coulomb static stress. Considerable number of aftershocks have occurred in the SW side of the epicentre. The correlation between high stress regions before and after the occurrence of earthquakes using thermal anomaly map and Coulomb static stress map has also been observed. Estimated total seismic moment is 2.98 x1024 dyne-cm corresponding to Mw 5.62 which is again comparable to seismological estimate of Mw 5.6 (USGS).