(This is a paper submitted to GRL)

Understanding megathrust slip behavior is crucial for assessing fault physics and earthquake hazards in subduction zones. Here we investigate the coseismic and postseismic slip associated with the 2024 megathrust event in Hyuga-nada, Japan, using dense geodetic data and a finite-element model. Our preferred source model reveals a quasi-circular, thrust-dominated rupture with a geodetic Mw of 7.1 and a maximum slip of ~1.5 m. Compared to previous M~7 events in this region, this event occurred at relatively greater depths, ranging from 15 to 30 km, on the downdip edge of the inferred subducted Kyushu-Palau ridge. Similar to the 1996 doublet, the afterslip is broadly distributed along the deeper megathrust interface, overlapping with slow slip events. Considering together other megathrust behaviors, this margin differs from others with subducted geometrical irregularities in the relative positions of aseismic and seismic slip concerning these irregularities. This diversity highlights the site-specific effects of subducted irregularities.