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.