Tiny stresses are capable of triggering earthquakes and tremors in Arunachal Himalaya

Abstract

The Arunachal Himalaya has been hosting some notable events in the recent past. The tectonic history of Arunachal Himalaya is complex and has been influenced by several major tectonic events, including the 1950 Mw8.6 Assam-Tibet earthquake. In this study, we explored the effect of dynamic stresses generated by teleseismic events on the triggering of seismicity in the region. We analyzed 34 large teleseismic events since 2010 and found triggering during six events. The change in seismicity was also confirmed by analysis with the STA/LTA method. The triggering in the region occurred in the form of earthquakes and tremors. The dynamic stress as low as 1 kPa was found capable of triggering. The back-azimuth angle does not play an important role in the triggering. The angle direction of incoming waves with respect to the fault ~ 60° and ~ 120° is the possible reason for triggering in the region. The triggering occurred in the Mishmi and Main Central Thrust regions. The largest triggered event, ML2.3, was triggered 7.5 h after the 2012 Indian Ocean earthquake of Mw8.6. The region is tectonically very sensitive and tiny stresses are capable of triggering seismicity in Arunachal Pradesh.