2018_EJRNL_PP_PARAM_K_GAUTAM_1.pdf
Terbatas  
» Gedung UPT Perpustakaan
Terbatas  
» Gedung UPT Perpustakaan
Co-seismic ionospheric disturbances (CIDs) due to different source characteristic earthquakes are investigated
through GPS-derived vertical total electron content (VTEC). We investigated VTEC changes related with
Moderate, Strong, Major and Great earthquakes occurred at different tectonic settings in both Himalaya and nonHimalayan regions. The VTEC and its anomalies are computed using GPS data obtained from the local network
of GPS stations in Himalaya with the IGS stations surrounding the epicentre region. Irrespective of the source
characteristics, significant CIDs are observed during Major and Great earthquakes, namely; (i) the Mw 7.8, 25th
April 2015 Gorkha earthquake, (ii) the Mw 7.6, 8th October 2005 Kashmir earthquake, and (iii) the Mw 8.6,
28th March 2005 Nias–Simeulue earthquake.
The VTEC anomalies due to the Gorkha event are observed 21.15 min after the earthquake origin time and
continued till 22.78 min with the amplitude range from ?0.530 to 0.517 ( ± 0.11) TECU. CIDs associated with
the Kashmir earthquake are noticed only at two GPS sites (NADI and PAN2) roughly after 23 min of the
earthquake occurrence. But, it continued around 14 min with the amplitude range from ?0.12 to 0.177 TECU
( ± 0.02 TECU = 1?). However, for the case of Ocean-Island Arc Nias–Simeulue earthquake, anomalous CIDs
were observed only at GPS site NTUS, where the disturbances started around 25.58 min later and continued
around 17.92 min with amplitude range from ?0.077 to 0.058 TECU ( ± 0.02 TECU = 1?). We inferred that the
CIDs originated because of earthquakes in Himalaya have relatively larger VTEC magnitudes (> 15 TECU) that
propagates faster in reaching and registering in the ionospheric layers compared with the non-Himalayan
earthquakes. Secondly, different lithospheric-ionospheric coupling mechanism is operating in transferring the
seismic energy, which originated from the Continent-Continent and the Tsunami genic Ocean-Island Arc collision zone, to the ionosphere