Seismic implications of creeping and coupled segments along the Philippine fault in Leyte from GNSS and InSAR data

We integrate GNSS and InSAR observations to investigate the interseismic and coseismic behavior of the Philippine Fault (PhF) in Leyte Island, central Philippines. Using a Bayesian dislocation framework applied along 11 fault-perpendicular profiles, we resolve fault geometry and slip-related kinematic parameters. The PhF accommodates aseismic deformation, with high creep rates of ∼37 mm/yr along the northern and southern segments and lower rates of ∼15 mm/yr along the central segment. Slip-deficit rates are spatially heterogeneous and reach up to ∼31−[jls-end-space/]33 mm/yr in the northern and central segments, indicating the presence of coupled patches. Baseline inversions further resolve a coupled mid-crustal asperity beneath central Leyte, spatially coincident with the source region of the 2017 Mw ∼6.5 Leyte earthquake. Coseismic modeling shows that Leyte event was confined to the shallow portion of the fault, releasing up to ∼1.8 m of slip within the upper ∼7 km. The modeling results also reveal geodetic evidence for a subparallel fault strand in the central segment, implying that slip deficit within the locked zone of the PhF may be redistributed across multiple strands rather than concentrated on a single fault trace. Comparison with historical seismicity, together with interseismic slip-deficit estimates, suggests a recurrence interval of ∼70–80 years for large earthquakes in central Leyte.