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Geodetically Estimated Ground Displacement and Fault Motions of the 2024 Noto Peninsula Earthquake

Description: 

An intense seismic swarm and transient crustal deformation have started in the Noto Peninsula, central Japan since the end of 2020, followed by a magnitude 7.5 earthquake occurred on January 1, 2024. Here we report on GNSS- and SAR-detected ground deformation and the geodetically estimated fault model. The GNSS data show that the northern part of the peninsula which is distributed in the east-west orientation uniformly moves westward with ~2 m at most. Large uplifts with ~ 1 m are observed at stations deployed in the northern coast of the peninsula. SAR-derived deformation map estimated by InSAR and pixel offset methods unveils the detailed spatial distribution of the displacement field. Large uplift is distributed along the northern coast with two main areas: The maximum uplift reaches ~4 m in the northwestern tip of the peninsula, and the second largest uplift, reaching ~2 m, is located in the west of the epicenter. GNSS data also detect significant post-seismic deformation. Northwestward displacements with ~1-2 cm are widely observed not only in the peninsula but also in areas 50-100 km away from the source region. Subsidence and upheaval are observed within and outside the peninsula, respectively.

Our fault model for the coseismic deformation consists of three fault segments with almost pure reverse motions: The westernmost fault extending a north-northeast orientation has a slip amount of ~10 m which produces the uplift of ~4 m on the ground. The fault next to the east extends in almost east-west orientation along the coast, and includes a right-lateral slip motion. The easternmost fault segment changes direction to the northeast on the west side of the epicenter, and has a large slip off the east coast of the tip of the peninsula. The post-seismic deformation can be explained by a slip off the east coast of the tip of the peninsula on the easternmost segment.

Acknowledgements: ALOS-2 data were provided from the Earthquake Working Group under a cooperative research contract with JAXA (Japan Aerospace Exploration Agency). The ownership of ALOS-2 data belongs to JAXA.

Session: The 2024 Magnitude 7.5 Earthquake and the Associated Earthquake Swarm Beneath the Noto Peninsula, Central Japan - I

Type: Oral

Date: 5/3/2024

Presentation Time: 08:15 AM (local time)

Presenting Author: Tomokazu

Student Presenter: No

Invited Presentation: Yes

Authors