Fault Model of the 2024 Noto Peninsula Earthquake Based on Aftershock, Tsunami, and GNSS Data

Abstract

On January 1, 2024, at 16:10 (local time), a magnitude (Mw) 7.5 earthquake occurred on the Noto Peninsula, Japan. Japan Meteorological Agency seismic intensity scale of 7 was observed and a tsunami warning was issued for a wide area along the Japan Sea. In this study, we constructed the finite fault model of this earthquake. First, we estimated the fault geometry based on the aftershock within 7 days after the mainshock, and then, estimated the slip distribution using the tsunami and GNSS data. Most of the obtained fault geometry agreed with the one detected by the Japan Sea earthquake and tsunami project (JSPJ) in the strike angle but not in the dip angle; the angles were more gradual. The slip distribution had two large slip areas on the east and west sides of the hypocenter. The model also indicated that the eastern part of the fault, or the fault buried under the sea floor, generated the tsunami which was dominant east of the peninsula. In the west of the peninsula, on the other hand, the tsunami generated by the westernmost fault, or the inland fault under the peninsula, hit first, and then the tsunami propagating from the east of the peninsula arrived.

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).…”