Coseismic Source Model of the 2017 Mw 6 5 Surigao Philippines Earthquake from GPS and DInSAR data

Abstract

2017 Mw 6 5 Surigao earthquake occurred at 10 km far away from the northeastern Mindanao Island Philippines Its focal depth is 10 km while caused damage in neighboring islands especially in the Surigao City on northeastern Mindanao Island is the most serious This earthquake provides an opportunity to build a coseismic source model of northeastern Mindanao Island to recognize the fault characteristics Two geodetic observations of GPS and DInSAR data are used to analyze the crustal deformation of this event 10 GPS stations data processed with Bernese v 5 0 software to obtain the offset in horizontal and vertical components The maximum coseismic GPS horizontal displacement is about 14 cm in station PSUR near Surigao City To obtain a large area of ground motion Sentinel-1 SAR images are applied to generate a interferogram with GMTSAR software The largest LOS change appears in the south of Surigao City with an offset of 22 cm While two datasets which show high-correlation by projection analysis are used to establish the source model together The optimal fault geometry is obtained from the uniform-slip model with Markov Chain Monte Carlo algorithm while the slip distribution is verified from the distributed-slip model The optimal result reveals this is a strike-slip event and the maximum slip of 1 m appears near the epicenter near the surface An asperity on northeastern Mindanao Island ruptured into the surface shows a large slip of 60 cm slip as similar as the offset of surface rupture Moreover an asperity shows out beneath surface with 18 km depth in the southeast of Surigao City which is considered as the main factor to cause the serious damage The energy release of this earthquake mainly show in three fault segments Compared the moment with historical earthquake events the earthquake recurrence interval of northeastern Mindanao Island is about 65 years The model result also indicates the earthquake made a smaller mean slip and larger rupture area on three fault segments which features as the transition zone between creeping and locked

Date of Award	2018 Aug 28
Original language	English
Supervisor	Kuo-En Ching (Supervisor)