Rapid earthquake-tsunami modeling: The multi-event, multi-segment complexity of the 2024 Mw 7.5 Noto Peninsula Earthquake governs tsunami generation

Abstract

The January 1st, 2024, moment magnitude (Mw) 7.5 Noto Peninsula earthquake ruptured in complex ways, challenging timely analysis of the tsunami generation. We present rapid and accurate tsunami models informed by a 6-subevent centroid moment tensor (CMT) model that we obtain by inverting teleseismic and strong motion data and validation against geodetic observations. We identify two distinct bilateral rupture episodes, including six subevents and a re-nucleation episode at its hypocenter 20 seconds after its initiation, likely aided by fault weakening. We construct a complex uplift model that aligns with known fault system geometries and is critical in modeling the observed tsunami. Our tsunami simulation can explain wave amplitude, timing, and polarity of the leading wave, which are crucial for tsunami early warning. Analyzing a 2000 multi-CMT solution ensemble and comparing to alternative rapid source models, we highlight the importance of incorporating complex source effects for realistic tsunami simulations.

A Multiplex Rupture Sequence under Complex Fault Network due to Preceding Earthquake Swarms during the 2024 Mw 7.5 Noto Peninsula, Japan, Earthquake

“…S1). Synthetic Aperture Radar (SAR) data (Geospatial Information Authority of Japan, 2024) show two major patches of deformation on the western side of the epicenter, including vertical displacement of up to about 4 m. A tsunami was also recorded at gauges along the coast (Fujii & Satake, 2024;Mizutani et al, 2024;Kutschera et al, 2024).…”

A Multiplex Rupture Sequence Under Complex Fault Network Due To Preceding Earthquake Swarms During the 2024 Mw 7.5 Noto Peninsula, Japan, Earthquake

“…The dip directions of the aftershocks are not obvious, but they roughly show southeastward dips on the western side of the epicenter and northwestward dips on the eastern side (Figure S1 in Supporting Information S1). Synthetic Aperture Radar (SAR) data (Geospatial Information Authority of Japan, 2024) show two major patches of deformation on the western side of the epicenter, including vertical displacement of up to about 4 m. A tsunami was also recorded at gauges along the coast (Fujii & Satake, 2024;Kutschera et al, 2024;Mizutani et al, 2024).…”