Source parameters of the Fatehjang, Pakistan earthquake (Mw4.1) of 28 August 2020

Fatehjang is a low seismicity area located in Northern Punjab, Pakistan, where relatively stable intraplate environment has mostly caused only minor earthquakes. This study considers the only moderate earthquake ( M W 4.1) in the last 10 years that occurred on August 28, 2020. Full-waveform inversion method was used in this study utilizing four different velocity models. The variance reduction and condition number were used to compare the calculated solutions from the four-velocity models. A large variance reduction and small condition number of the local velocity model indicates that it is more suitable than the three regional and global velocity models. Thrust faulting with a slight contribution of strike-slip movement with shallow focal depths is depicted in the obtained solution. Results using the selected local velocity model are in line with the subsurface interpreted geological structure using the seismic reflection profiles of the Ratana oil field some 48 km away from the epicenter of the seismic event. The source parameters from P-wave displacement spectra using Brune’s source model were also estimated, and the calculated moment magnitude was found to be consistent with the waveform inversion results.