Surface rupture kinematics of the 2020 Mwg6.6 Masbate (Philippines) earthquake determined from optical and radar data

Abstract

Optical correlation, interferometry, and field investigation of laterally offset features were undertaken to analyze the kinematics of the 2020 Mwg6.6 Masbate earthquake. Ground displacement fields show a peak left-lateral offset of 0.6gm corresponding to Mwg6.6 geodetic moment magnitude, with an average 0.4gm left-lateral slip. The slip distributions also indicate a single asperity located g1/4200gm SE of the centroid. Post-seismic deformation estimates from interferometry highlight an at least 0.14gm left-lateral offset consistent with a Mwg6.2 post-seismic moment magnitude. The total and post-seismic slip distributions coincide with each other, with both peaks adjacent to the centroid. Slip measurements and the g1/428.2-41gkm rupture length estimates from field and remote sensing datasets characterize the Masbate segment as capable of producing long ruptures with significant offsets despite the presence of interseismic creep. Post-seismic interferograms resolved the rupture far better than optical correlation, which was degraded due to high-Amplitude noise from sensor and environmental sources. Nevertheless, this review of the 2020 Mwg6.6 Masbate earthquake provides a comprehensive slip measurement of the surface rupture and demonstrates the presence of two transtensional basins in the Masbate province, revealing new insights into the seismic hazard and seismotectonic setting of the central Philippines.