Transient Effects in Atmosphere and Ionosphere Preceding the 2015 M7.8 and M7.3 Gorkha–Nepal Earthquakes

We analyze retrospectively/prospectively the transient variations of six different physical parameters in atmosphere/ionosphere during M7.8 and M7.3 earthquakes Nepal, namely: 1) outgoing longwave radiation (OLR) at top atmosphere (TOA); 2) GPS/TEC; 3) very-low-frequency (VLF/LF) signals receiving stations Bishkek (Kyrgyzstan) Varanasi (India); 4) Radon observations; 5) Atmospheric chemical potential from assimilation models; and; 6) Air Temperature NOAA ground stations. found that mid-March 2015, there was a rapid increase observed by satellites. This anomaly located close to future epicenter reached maximum on April 21–22. The GPS/TEC data analysis indicated an variation electron density, reaching value 22–24. A strong negative TEC crest EIA (Equatorial Ionospheric Anomaly) occurred 21, positive recorded 24, 2015. behavior VLF-LF waves along NWC-Bishkek JJY-Varanasi paths has shown abnormal 21–23, several days before first, stronger earthquake. Our continuous satellite OLR revealed this new May 3, which why we anticipated another major event area. On 12, earthquake occurred. results show coherence between appearance these pre-earthquake transient’s effects ionosphere (with short time-lag, hours up few days) occurrence 2015 events. spatial characteristics anomalies were associated with large area but inside preparation region estimated Dobrovolsky-Bowman. nature simultaneous satellite, GPS/TEC, VLF/LF suggest they follow general temporal-spatial evolution pattern been seen other worldwide.