Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra - Université Paris Cité Accéder directement au contenu
Article Dans Une Revue Earth and Planetary Science Letters Année : 2024

Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra

Xin Wang
  • Fonction : Auteur
Shengji Wei
Connectez-vous pour contacter l'auteur
Catalina Morales-Yáñez
Ling Chen
Tianyao Hao
  • Fonction : Auteur
Liang Zhao
  • Fonction : Auteur correspondant
  • PersonId : 972572

Connectez-vous pour contacter l'auteur

Résumé

Geometry and frictional states of the megathrust in subduction zones play critical roles on the rupture extent, hence the magnitude, of great earthquakes. However, their details are often difficult to obtain, primarily due to limited offshore geophysical observations. Here we overcome this challenge by precisely determining source parameters (i.e., location and focal mechanism) of medium-sized earthquakes using global broadband seismic waveform data. The dip angles of 108 Mw 5.0+ plate interface events from 1990 to 2017 in the central Sumatran subduction zone are tightly constrained by waveform inversion, and their locations are refined with surface-wave relocation and depth phases modeling. Our results reveal compact trench parallel earthquake belts at the up-dip and down-dip boundaries of the ruptures of the Mentawai 2007 Mw 8.4 and Mw 7.9 earthquakes. The down-dip seismicity belt marks ∼8º bending of the plate interface, suggesting that the change of fault geometry may have played a role in halting the megathrust rupture along with thermal effects. The up-dip seismicity belt shows a clear spatial complementarity to the largest events’ slip distribution. This belt is quite narrow (∼20 km) for the Mw 8.4 rupture but much broader (∼50 km) for the Mw 7.9 event. The combination of the up-dip seismicity belt and slip distributions matches well with the positive residual bathymetry and gravity anomalies, suggesting that these events resulted from long-term coupling on the plate boundary. Our findings suggest the importance of considering both up-dip and down-dip seismicity belts, along with residual bathymetry and gravity data, in understanding megathrust rupture behaviors and assessing the associated hazards.
Fichier non déposé

Dates et versions

hal-04584621 , version 1 (23-05-2024)

Identifiants

Citer

Xin Wang, Shengji Wei, Catalina Morales-Yáñez, Zacharie Duputel, Ling Chen, et al.. Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra. Earth and Planetary Science Letters, 2024, 637, pp.118726. ⟨10.1016/j.epsl.2024.118726⟩. ⟨hal-04584621⟩
47 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More