Failure of A Deep Asperity in Hyuga-nada, Japan: The August 8, 2024 Mw
7.1 Subduction Zone Earthquake
Abstract
(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.