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Shallow crustal rupture in a major MW 7.5 earthquake above a deep crustal seismic swarm along the Noto Peninsula in western Japan.

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Title: Shallow crustal rupture in a major MW 7.5 earthquake above a deep crustal seismic swarm along the Noto Peninsula in western Japan.
Authors: Liu, Chengli1 (AUTHOR) liuchengli@cug.edu.cn, Bai, Yefei1,2,3 (AUTHOR) yfbai@zju.edu.cn, Lay, Thorne4 (AUTHOR), He, Ping1 (AUTHOR), Wen, Yangmao5 (AUTHOR), Wei, Xiaoran2 (AUTHOR), Xiong, Neng6 (AUTHOR), Xiong, Xiong1 (AUTHOR)
Source: Earth & Planetary Science Letters. Dec2024, Vol. 648, pN.PAG-N.PAG. 1p.
Subjects: Properties of fluids, Earthquake swarms, Earthquakes, Synovial fluid, Peninsulas, Surface fault ruptures
Abstract: • Unusual large shallow crustal faulting occurred above a deep, long-duration seismic swarm along the Noto Peninsula. • The 2024 M W 7.5 earthquake is the largest recorded along the Noto Peninsula, had a slow initial rupture expansion. • Weak initial seismic energy indicates a gradual nucleation process, possibly influenced by deeper fluid accumulation. • A dominant deep large-slip patch and a weaker shallow slip suggests non-uniform fault properties and fluid migration effects on fault weakening. A damaging M W 7.5 earthquake struck the western coast of Japan along the Noto Peninsula on January 1, 2024. The initiation of large shallow earthquakes along the Noto Peninsula, particularly above deeper long-duration patchy seismic swarms, presents an unusual seismic phenomenon that warrants in-depth investigation of their interactions. The 2024 earthquake nucleated with an initial low average rupture velocity of 0.5–1.0 km s-1 near the up-dip end of a long-lasting seismic swarm that commenced in November 2020. Analysis of dense seismic, geodetic, and tsunami observations provides good resolution of large shallow slip in the crust below the peninsula and extending offshore to the northeast, revealing a heterogeneous slip distribution characterized by bilateral two-stage rupture expansion during the faulting. Up to 8 m of slip occurred in several patches along ∼150 km of the southeastward-dipping thrust fault, which extends to near the seafloor along the northwest side of the peninsula. Up to 5 m of uplift occurred along the peninsula's northwestern coast. Up-dip fluid migration appears to have weakened the shallow fault prior to failure and influenced the initial slow rupture expansion, highlighting the need to monitor the evolution of worldwide swarms. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:• Unusual large shallow crustal faulting occurred above a deep, long-duration seismic swarm along the Noto Peninsula. • The 2024 M W 7.5 earthquake is the largest recorded along the Noto Peninsula, had a slow initial rupture expansion. • Weak initial seismic energy indicates a gradual nucleation process, possibly influenced by deeper fluid accumulation. • A dominant deep large-slip patch and a weaker shallow slip suggests non-uniform fault properties and fluid migration effects on fault weakening. A damaging M W 7.5 earthquake struck the western coast of Japan along the Noto Peninsula on January 1, 2024. The initiation of large shallow earthquakes along the Noto Peninsula, particularly above deeper long-duration patchy seismic swarms, presents an unusual seismic phenomenon that warrants in-depth investigation of their interactions. The 2024 earthquake nucleated with an initial low average rupture velocity of 0.5–1.0 km s-1 near the up-dip end of a long-lasting seismic swarm that commenced in November 2020. Analysis of dense seismic, geodetic, and tsunami observations provides good resolution of large shallow slip in the crust below the peninsula and extending offshore to the northeast, revealing a heterogeneous slip distribution characterized by bilateral two-stage rupture expansion during the faulting. Up to 8 m of slip occurred in several patches along ∼150 km of the southeastward-dipping thrust fault, which extends to near the seafloor along the northwest side of the peninsula. Up to 5 m of uplift occurred along the peninsula's northwestern coast. Up-dip fluid migration appears to have weakened the shallow fault prior to failure and influenced the initial slow rupture expansion, highlighting the need to monitor the evolution of worldwide swarms. [ABSTRACT FROM AUTHOR]
ISSN:0012821X
DOI:10.1016/j.epsl.2024.119107