Atmospheric anomalies associated with Mw>6.0 earthquakes in Pakistan and Iran during 2010-2017

Recent advances on satellite-based measurement of different atmospheric constituents at different heights provide sufficient evidences of short and long-term earthquake (EQ) precursors. In this paper, atmospheric anomalies are investigated related to three large magnitude M-w > 6.0 EQs in Pakistan and Iran during 2010-2017 (i.e., January 18, 2011 (M-w 7.2, Southwestern Pakistan), April 16, 2013 (M-w 7.7, East of Khash Iran) and February 07, 2017 (M-w 6.3, Pasni, Pakistan)). For this purpose, satellite based Outgoing Longwave Radiation (OLR), Surface Temperature (ST), Aerosol Optical Depth (AOD) and NO2 are investigated by statistical bounds of median and standard deviation for two months before and one month after the occurrence of each event. We study the spatial OLR anomaly from National Oceanic and Atmospheric Administration/National Center for Environmental Prediction (NOAA/NCEP). Evidences suggest that abnormal atmospheric anomalies occur within one month before the main shock. For example, in case of M-w 7.2 southwestern Pakistan EQ, significant perturbations in daytime OLR are detected up to 21 days before the main shock, justifying the existence of huge amounts of energy over the tectonic lineaments. The OLR anomaly correlated with ST, AOD and NO2 during 15-21 days before the main shock, which may be attributed to the same event. Similarly, the OLR, ST, AOD and NO2 show irregularities before the 2013, M-w 7.7 East of Khash Iran EQ, where all the anomalies occur 9-10 days before the main shock. The anomalous OLR over the epicenter suggests the authenticity of all the temporal perturbations in the atmospheric parameters related to M-w 7.7 (Iran event). Furthermore, the atmospheric parameters are analyzed temporally by the statistical bounds before the M-w 6.3 (Pasni, Pakistan) EQ. All the parameters behave abnormally during 10-15 days following the M-w 6.3 Pakistan EQ and similarly subsequent spatial OLR enhancement over the epicenter may lead to the conclusion of an extensive energy emanation. The anomalies detected are consistent with the processes of stress activation of proxy defects at the Lithosphere-Atmosphere interface in the seismic breeding zone.