InSAR coseismic deformation field and seismogenic structure of the 2020 Mw6.0 Jiashi earthquake and the implication for the moderate-magnitude seismicity in the southwestern Tian Shan, western China

Wu, D.; Chen, Z.; Zimin, M.

Авторы: Wu Danruo, Chen Zhidan, Zimin Mikhail
Журнал: FRONTIERS IN EARTH SCIENCE
Номер: 11:1305519
Год издания: 2024
Издательство: Frontiers Media S.A.
Местоположение издательства: Lausanne, Switzerland
DOI: 10.3389/feart.2023.1305519
Аннотация: The Kepingtage fold-and-thrust belt in the southwestern Tian Shan in westernChina hosted the 2020 Mw 6.0 Jiashi earthquake with no apparent surfaceruptures. The thrust nappe structure in this region is characterized bymoderate-magnitude (Mw5.5-6.5) seismicity, but the seismogenic mechanismsand controlling factors remain under investigation. In this study, we utilizedSentinel-1A synthetic aperture radar satellite data to reconstruct the InSARcoseismic deformation field of the 2020 Jiashi earthquake. To address thelimitation imposed by residual orbital phases during the interferometricmeasurement, we proposed a novel automatic method that combinesascending and descending track data with terrain features for orbit refinement.Eight comparative testswere conducted to prove the effectiveness of the proposedmethod. Subsequently, we inverted the jointly constrained deformation field afterorbit correction to obtain the fault geometric parameters and slip distribution. Ourresults show that the 2020 Jiashi earthquake is characterized by right-lateraltranspressive motion. The smooth interference fringes demonstrate spatiallycontinuous surface uplift and subsidence without detectable coseismic surfaceruptures, with a maximum uplift of ~0.08m and a maximum subsidence of~0.03m, caused by the subsurface folding due to deep seismic rupture. Thisevent is best fitted by a north-dipping fault plane with a depth of 4.2 km, a dip angleof 11.6°, and a strike of 276° beneath the Keping thrust fault. In terms of variousgeometric parameters of the fault, the inversion results of this study are generallysimilar to the focal mechanism solution provided by USGS (MWb), but are differentfrom the focal mechanism solutions of other institutions and previous researchresults. Combined with the published geological investigations and seismicreflection surveys, we suggest that the seismogenic structure of the 2020 Jiashiearthquake is the lower ramp of the Keping thrust fault and the abrupt fault bendbetween the lower and upper ramp may limit the propagation of the coseismicrupture to the surface. The limited rupture of this event is dominated by theirregularities in fault geometry along strike and dip, as well as the lower rock strength of the cover above the detachment, which contribute to a deeperunderstanding of the seismic behavior in fold-and-thrust belts and the moderatemagnitudeseismicity in the southwestern Tian Shan region.
Добавил в систему: Зимин Михаил Викторович

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InSAR coseismic deformation field and seismogenic structure of the 2020 Mw6.0 Jiashi earthquake and the implication for the moderate-magnitude seismicity in the southwestern Tian Shan, western Chinaстатья Исследовательская статья

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