Tsunami hazards and risks from the Philippine Trench: The cases of 2012 and 2023 Mw 7.6 tsunamigenic earthquakes

Abstract

This paper presents a novel study on tsunami hazard and risk for the eastern Philippines, focusing on the underexplored Philippine Trench: a major tsunamigenic zone responsible for past destructive events. To address this pressing need, we model and analyze the generation mechanisms of two real M_w 7.6 events, occurred in August 2012 and December 2023, and expand our analysis to three hypothetical giant events: M_w 8.0, M_w 8.5, and M_w 9.0. The maximum tide gauge amplitudes recorded from the two actual M_w 7.6 events were 12.5 cm for the 2023 tsunami and 3.7 cm for the 2012 event. The tsunami waves from the 2023 tsunami had longer periods (6.7–28.2 min) compared to those from the 2012 tsunami (8.0–18.3 min), which is attributed to the deeper water surrounding the 2012 event's source area. Modeling a hypothetical M_w 9.0 event indicates that maximum coastal tsunami heights could reach up to 17.4 m, making it comparable to the giant tsunamis of 2011 in Japan and 2004 in the Indian Ocean. We conducted a tsunami risk analysis for the coastal town of Dapa for an M_w 8.5 event, which revealed that 218 buildings, including a designated evacuation center, could be inundated.