Mining Seismic Anomaly from Satellite Microwave Big Data: Methodology and Case Studies

Seismicity-related anomaly analysis or earthquake precursor cognition is a great challenge for geo-electromagnetic signals mining and remote sensing application. To mining seismic anomaly from satellite data including microwave data is of extreme importance. A spatio-temporally weighted two-step method (STW-TSM) is developed to retrieve or to mine seismicity-related microwave brightness temperature (MBT) anomaly with microwave satellite big data from Aqua AMSR-E and/or FY-3B MWRI sensors. To remove the general trend of MBT to retrieve basic MBT residuals of the shocking year, historical microwave data were given varied time-weights according to respective time intervals with the shocking year. To eliminate the regional meteorological noise so as to retrieve cleaned MBT residuals actually related with seismic activities, adjacent pixels inside the seismic preparation zone were endowed with varied space-weights according to Euclidean distances away from the epicenter With Wenchuan earthquake sequence in May, 2008 and Nepal earthquake sequence in April and May, 2015 being case studies, this paper demonstrated the practical application of STW-TSM. Results showed that 1) significant strip-shaped MBT anomalies appeared near the epicenter of Wenchuan earthquake days before the main shocking and migrated with aftershocks moving northeastward 2) the horizontal strip MBT anomalies covered exactly the epicenters and seismic concentration zone of Nepal earthquakes during shocking days 3) the MBT anomaly zones behaved highly spatial overlap with geological quaternary strata and cliff-shaped mountainous region. The mined MBT anomalies are supposed to be related with the effects of rock dielectric constant variation, which is most likely to be caused by crust stress activated positive electricity carriers from deep crustal. This research is of particular meanings for mining MBT anomaly from satellite microwave big data, and for searching geo-electromagnetic signals related with seismicity.