Oblique Blind Faulting Underneath the Luzon Volcanic Arc During the 2022 M_w 7.0 Abra Earthquake, the Philippines

Unknown seismogenic structures lurking beneath convergent margins introduce substantial uncertainty in seismic hazard assessments. In northwestern Luzon, the M_w 7.0 Abra earthquake on 27 July 2022 highlights the seismic activity along an unmapped blind fault underneath the Cordillera Central. By integrating coseismic displacements constrained by radar satellite imagery and Global Navigation Satellite System, we image oblique coseismic slip at 11–22 km depth with peak slip of ∼1 m beneath the Philippine Fault Zone in northern Luzon. The southward propagation of coseismic slip and aftershocks terminated at a distance of 50 km from the northern end of the 1990 Luzon earthquake rupture, leaving a seismicity gap in between. Coulomb stress changes of reaching 2 bars are imparted at the shallow portions of the Vigan-Aggao and Abra River faults, where the updated 100-year seismic potential is increased to M_w 7.0–7.7, given the thick seismogenic layer of ∼30 km in northern Luzon.