Work

Reliable Fault Modeling of an Mw 7.1 Earthquake in Hyuganada Sea on 8 August 2024 by Offshore Tsunami Data From New Seafloor Network N‐net and Onshore GNSS Data

Year: 2025

Type: article

Abstract: We investigated tsunamis of an Mw 7.1 earthquake in the Hyuganada Sea in 2024, observed by a new dense and wide seafloor observation network, N‐net, installed in the western Nankai Trough. A joint inversion of the offshore tsunami and onshore GNSS data revealed a maximum slip of 2.4 m with a significant slip near the centroid from the teleseismic analysis. The joint inversion provided reliable constraints for both up‐dip and down‐dip extents of the fault, while the inversions using either data set showed limitations in the fault constraint. Comparisons with past earthquakes indicate the 2024 earthquake ruptured part of the asperity of the 1961 earthquake but not those of the 1996 earthquakes. Our fault modeling jointly using offshore and onshore data suggests the interplate seismic coupling ratio in this region is <0.4, which was much smaller than those in the anticipated megathrust earthquake source region in the Nankai Trough.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl115391

Authors: Tatsuya Kubota, Hisahiko Kubo, Tatsuhiko Saito

Institution: National Research Institute for Earth Science and Disaster Resilience

Language: English

Topic: earthquake and tectonic studies

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,190

Funders: Forskningsrådet om Hälsa, Arbetsliv och Välfärd, Japan Society for the Promotion of Science