22 Jun 2023
 | 22 Jun 2023

Surface Rupture Kinematics of the 2020 Mw6.6 Masbate (Philippines) Earthquake determined from Optical and Radar Data

Khelly Shan Sta. Rita, Sotirios Valkaniotis, and Alfredo Mahar Francisco Lagmay

Abstract. Optical correlation, interferometry, and field investigation of laterally offset features were undertaken to analyze the kinematics of the 2020 Mw6.6 Masbate earthquake. Coseismic displacement fields from optical correlation show a maximum displacement of 0.61 m corresponding to Mw6.64 geodetic moment magnitude and a lone asperity in Cataingan. Post-seismic deformation from interferometry highlights a maximum 0.14 m sinistral displacement equivalent to a Mw6.15 post-seismic moment magnitude, with coincident afterslip and coseismic slip distributions. The measured slip decreased towards the north, suggesting the presence of a slip barrier where stress can accumulate. Slip measurements and rupture length estimates characterize the Masbate segment as capable of producing unusually long ruptures with significant offsets despite the presence of 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, the resultant surface rupture morphology, as observed in optical correlation outputs and interferograms, demonstrated the presence of two transtensional basins in the north and south of the province, interlinked by a stepover of the respective Riedel shear zones. This review of the 2020 Mw6.6 Masbate earthquake reveals new insights into the seismic hazard and seismotectonic setting of Masbate province in Central Philippines.

Khelly Shan Sta. Rita et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-978', Gordon Woo, 02 Jul 2023
    • AC1: 'Reply on RC1', Khelly Shan Sta. Rita, 14 Jul 2023
  • RC2: 'Comment on egusphere-2023-978', Anonymous Referee #2, 21 Aug 2023
    • AC3: 'Reply on RC2', Khelly Shan Sta. Rita, 29 Sep 2023
  • RC3: 'Comment on egusphere-2023-978', Austin Elliott, 29 Aug 2023
    • AC2: 'Reply on RC3', Khelly Shan Sta. Rita, 29 Sep 2023

Khelly Shan Sta. Rita et al.

Khelly Shan Sta. Rita et al.


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Short summary
The ground movement and rupture produced by the 2020 Masbate earthquake in the Philippines was studied using satellite data. We highlighted the importance of the complementary use of optical and radar datasets. The slip measurements and field observations were used to improve our understanding of the seismotectonics of the region, which is critical for seismic hazard studies.