Co-seismic and Post-seismic Changes in ZTD and TEC of the 2015 Nepal Earthquake

We studied changes in the zenith total delay (ZTD) and total electron content (TEC) associated with the large 2015 Nepal earthquake (Mw 7.8) from GPS data received at HYDE, LCK3 International GNSS Service (IGS) stations and MSUN stations. The ZTD value, which is sensitive to tropospheric weather conditions, showed a sharp drop during and following the mainshock as well as the largest aftershock of the Nepal earthquake sequence. The changes in ZTD most likely represent changes in the atmospheric pressures. Effects of earthquake processes such as large stress drop, low radiation efficiency of the 2015 event, and conversion of elastic energy to shear heating (anelastic loss) during propagation of surface waves from large earthquakes over teleseismic distances contributes to the real ground deformation, as inferred from changes in GPS-derived ZTD. The coincident decrease in ZTD and TEC suggests hydration in the atmosphere by the joining of ions in the atmosphere during earthquakes.

GPS-derived ZTD values observed at HYDE (upper panel, black solid circles), MSUN (bottom panel, black solid circles) and LCK3 (bottom panel, orange open circles) stations during the Nepal earthquake. The ZTD values predicted by numerical weather model (NWM) studies at HYDE (red circles) are shown for comparison.

Citation: A. AKILAN, S. PADHY,V. P. DIMRI, H. SCHUH and K. K. ABDUL AZEEZ, 2021. Pure Appl. Geophys. external link