Analyzing Long Wave Radiation Data Associated with the 2015 Nepal Earthquakes Based on Multi-orbit Satellite Observations
The infrared anomaly index algorithm is proposed in this paper based on the advantages of RST (Satellite Technique Robust) and vorticity algorithm which have been used in application of detecting infrared anomaly. An MS8.1 and an MS7.5 earthquake, occurred at the front of the India-Eurasia collision belt, struck Nepal on April 25th and May 12th, 2015. We analyzed the temporal and spatial variations of outgoing long wave radiation (OLR) obtained from satellite observations around the time of the two earthquakes using RST and anomaly index algorithms. The Meteorological satellite data we used include night-time data (once daily) from the polar orbit NOAA/AVHRR and three hours data (8 times daily) of the Chinese geostationary satellite FY-2D.#br#The results show that RST algorithm provides no anomalous solutions around the epicenter of two earthquakes. In comparison the infrared anomaly index algorithm did provide an anomaly detection, and specifically we found an increase of emitted infrared radiation on the west of the MS8.1 epicenter on April 15th 2015. The thermal anomaly derived from NOAA data reached the maximum on April 24 at 100 kilometers west of the MS8.1 epicenter, and then disappeared gradually. In addition another thermal anomaly was detected on May 10 at 200 kilometers east of the MS7.5 epicenter. Based on three-hour data analysis from FY-2D, we found on April 24 a dynamic evolution in the anomalous process, the same day when the NOAA data thermal anomaly reaches the maximum. In this case FY-2D satellite data provided complimentary data to the initial detection based on low temporal/spatial resolution data obtained from NOAA and improved the final solution in the location of the anomaly. Our initial results suggest that systematic use of multi-orbit satellite observation can provide reference to monitor the pre-earthquake changes of thermal radiation.
SUN Ke, SHAN Xin-Jian, Dimitar Ouzounov et al. 2017. Analysis of longwave radiation characteristics of Nepal earthquake based on multi-orbital satellite observations. Chinese Journal of Geophysics, 60(9): 3457-3465, doi: 10.6038/cjg20170915