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[S13-P-09] Source inversion and stochastic ground motion modelling of the August Mw 6.8 Myanmar earthquake
An intermediate-depth Mw 6.8 earthquake struck Myanmar on 24 August 2016. This earthquake was felt throughout the country and caused some damage in the Chauk and Bagan areas. USGS reported the earthquake mechanism as a reverse fault (Strike1: 166, Dip1: 83, Rake1: 89 and Strike2: 356, Dip2: 7, Rake2: 100), which would be cutting the subducting slab near vertically or near horizontally. There has been no previous intermediate depth earthquake with a similar mechanism in the Myanmar region from available moment tensor catalogs. We study the earthquake source mechanism and slip distribution using teleseismic body-wave inversion implemented in the Kikuchi-Kanamori code. We used 33 P- and 34 SH-waves data from stations at teleseismic distances (30º to 90 º). Testing different earthquake depths during the inversion, we found the lowest variance at 85 km depth. We set the fault plane size to 35 x 35 km2 and divided into a 5 km grid. We obtained a similar earthquake mechanism to the USGS result, i.e. reverse faulting event (Strike1: 165, dip1: 82, rake1: 97 and Strike2: 303, Dip2: 11, Rake2: 49). Regarding the slip distribution, we note that the maximum slip is 0.9 m and is located at the down-dip edge of the fault plane. This earthquake occurred within the subducting Indian-plate indicating slab parallel tension. We applied stochastic finite-fault ground-motion simulation based on a dynamic corner frequency to simulate the ground motion for this event. The results were compared to seven strong motion stations in the Myanmar region to validate our simulated values. The closest recording was made ~50 km from the epicenter. The damage reported by the Department of Meteorology and Hydrology of Myanmar is consistent with the relatively high ground motion.