Impacts and causative fault of the 2022 magnitude (Mw) 7.0 Northwestern Luzon earthquake, Philippines

At 00:43 UTC on 27 July 2022, a 15-km deep major earthquake with magnitude (M w ) 7.0 struck Northwestern Luzon, Philippines. The strongest ground shaking felt was at PHIVOLCS Earthquake Intensity Scale (PEIS) VII (destructive), equivalent to Modified Mercalli (MMI) VII, in Abra and along the coastal areas of Ilocos Sur. More than thousand landslides, rockfalls tension cracks were mapped, near epicentral region, northwestern part Central Cordillera. Most landslides shallow-seated, many which situated road cuts. Liquefaction manifested as lateral spreads, sand boils, fissures, subsidence, localized swelling documented Sur river channels Sea level disturbance also observed some La Union. Damages buildings infrastructures that experienced PEIS VI (very strong), MMI (destructive). data, including hypocentral location, aftershock distribution, focal mechanism solutions strong motion InSAR observation indicate generated by an almost north-south striking reverse left-lateral oblique fault is gently dipping east. There no clear indication surface rupture based analysis field investigation. spatial distribution geologic impacts, such earthquake-induced liquefaction, strongly controlled causative fault, direction propagation geology. Peak acceleration (PGA) records show unidirectional are congruent impacts. Although parameters, deformation data suggest River Fault probable derived geometry kinematics from seismotectonic challenge our existing understanding nature Fault, well other segments Philippine Fault. need understand these sources country needed for better seismic hazard risk assessment.