An update to seismic hazard levels and PSHA for Lombok and surrounding islands after earthquakes in 2018

Abstract

A series of earthquakes occurred at the northern part of Lombok Island during July–September 2018 with the highest Mw7.0 5th August 2018 that caused the death of hundreds of people and ruined thousands of buildings. The earthquakes were triggered on the Flores Thrust located at the back arc zone and at only 50 km distance from the island, leading to multiple seismic hazards to Lombok and surrounding islands. The thrust could possibly be the dominant current seismic sources; however, the megathrust sources also contributed to the hazards due to the subduction between the Indo-Australia and Eurasia tectonic plates in the Nusa Tenggara region. An updated probabilistic seismic hazard analysis was, therefore, conducted on recent seismicity, detailed tectonic background, and suitable ground motion prediction equations, to determine higher seismic parameter values than the 2017 models. This means that Lombok and surrounding islands exposed to higher seismic hazards than those predicted before the earthquake events in 2018.