SIMULATION OF EARTHQUAKE INTENSITY FOR TSUNAMI PREDICTION AND DISASTER RISK MANAGEMENT

Abstract

On January 15, 2023, a major earthquake with Mw 6.2 occurred in the northern part of Sumatra, Indonesia, and generated widespread ground shaking around III – V MMI without any damages. The hypocenter was located at a shallower depth than the common slab contour, which may address another blind tectonic system called backthrust. An extended waveform inversion and hypocenter relocation analysis is demonstrated to identify the responsible system. A total of 1,750 earthquakes were compiled from the 10-year catalog (2010 – 2022) and recorded by 72 stations associated with 1,2536 P-phase and 5,604 S-phase. Up to 85% (1211) of the total earthquakes were successfully relocated, while 15% (103) were not relocated because they did not meet the predetermined criteria. Furthermore, the mainshock was resolved with a thrusting fault with NW – SE orientation, steeply dipping to the SW direction, and a moment magnitude estimation of Mw 6.2 ± 0.03 at a depth of 35.50 ± 2 Km. The focal parameters include two nodal planes, i.e., the 1^st nodal plane with strike 319°, dip 15.5°, and rake 101° while the 2^nd nodal plane with strike 127°, dip 74.8° and rake 86.8°. The results successfully show the existence of the blind back thrust in the Sumatra subduction zone, which will provide new insight and contribute to the recent tectonic system in the northern part of Sumatra and its surroundings.