Mechanism and implications of the post-seismic deformation following the 2021 M_w 7.4 Maduo (Tibet) earthquake

verfasst von

Fei Chen, Faqi Diao, Mahmud Haghshenas Haghighi, Yuebing Wang, Yage Zhu, Rongjiang Wang, Xiong Xiong

Abstract

A major earthquake shook the Chinese county of Maduo, located in the Songpan-Ganzi terrane on the Tibetan Plateau, on 21 May 2021. Here, we investigate the post-seismic deformation process of this event, with the aim to understand the fault geometry, friction behaviour and regional rheology. To keep the self-consistency between co- and post-seismic deformation models, we first constrain the fault geometry and coseismic slip model of this event, which are directly used in modelling the post-seismic deformation. The coseimsic slip model reveals that the majority of coseismic slip is confined at the middle (3–15 km) of the brittle layer, leading to significant shallow slip deficit. Secondly, we obtain the post-seismic deformation in the first 450 d following the 2021 Maduo earthquake using the GPS and InSAR displacement time-series data. Thirdly, a combined model incorporating afterslip and viscoelastic relaxation is built to explain the observed post-seismic deformation. Our results suggest that the viscoelastic relaxation effect should be considered in the observation period, in order to avoid the unphysical deep afterslip in the ductile lower crustal layer. Combined analysis on viscosities inferred from this study and previous studies suggests a weak lower crust with steady-state viscosity of 10¹⁸–10¹⁹ Pa s beneath the Songpan-Ganzi terrane, which may give rise to the distributed shear deformation and the development of subparallel secondary faults within the terrane. Besides, the inferred afterslip on uppermost patches of the middle fault segment suggests a rate-strengthening frictional behaviour that may be related to the coseismic slip deficit and rupture arrest of the Maduo earthquake.

Organisationseinheit(en)

Institut für Photogrammetrie und Geoinformation

Externe Organisation(en)

China University of Geosciences (CUG)
China Earthquake Administration (CEA)

Typ

Artikel

Journal

Geophysical journal international

Band

237

Seiten

203-216

Anzahl der Seiten

14

ISSN

0956-540X

Publikationsdatum

04.2024

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Geophysik, Geochemie und Petrologie

Elektronische Version(en)

https://doi.org/10.1093/gji/ggae034 (Zugang: Offen)