More major earthquakes at the Nepal Himalaya? – Study on Coulomb stress perspective

• Published in: Physics of the earth and planetary interiors 2018-07, Vol.280, p.1-19
• Main Authors: Som, S.K., Sarkar, Subhrasuchi, Dasgupta, Soumitra
• Format: Article
• Language: English
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/j.pepi.2018.04.005

•Aftershocks of 7.8 Mw, April 2015 Nepal earthquake concentrate in high Coulomb stress regions.•Stress released on high dip slip and stress enhanced on high strike slip parts.•Aftershock of 7.3 Mw activated due to linking thrust fault of transverse strike slip fault.•Associated thrust and transverse faults are on high stress condition.•High stress regions are potential for +7 magnitude earthquake. On April 2015 a major earthquake of 7.9 Mw occurred in the Nepal Himalaya, followed by 553 earthquakes of local magnitude greater than 4.0 within the first 43 days including another major event of 7.3 Mw. We resolve the static coulomb failure stress (CFS) change onto the finite fault models of 7.9 Mw after Elliott et al. (2016) and Galezka et al. (2015) and its effect on associated receiver faults. Correlation of aftershocks with the enhanced CFS condition shows that the Elliott et al. (2016) model explains 60.4% and the Galezka et al. (2015) model explains about 47.7% of the aftershocks in high stress regions. Aftershocks were poorly spatially correlated with the enhanced CFS condition after the 7.9 Mw main shock and can be explained by correlation with release of seismic energy from the associated secondarily stressed prominent thrust planes and transverse faults. Stress resolved on the associated receiver faults show increased stress on both transverse and thrust fault systems with the potential of triggering significant aftershocks or subsequent main shocks.