DOI: 10.1016/j.epsl.2021.117081
论文题名: Interplay of seismic and a-seismic deformation during the 2020 sequence of Atacama, Chile
作者: Klein E. ; Potin B. ; Pasten-Araya F. ; Tissandier R. ; Azua K. ; Duputel Z. ; Herrera C. ; Rivera L. ; Nocquet J.M. ; Baez J.C. ; Zigone D. ; Madariaga R. ; Ampuero J.P. ; Ruiz S. ; Vigny C.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 570 语种: 英语
中文关键词: Atacama
; Chilean subduction zone
; earthquake sequence
; GPS
; post seismic
; seismology
英文关键词: 3D modeling
; Earthquakes
; Atacama
; Chilean subduction zone
; Coseismic slips
; Earthquake sequences
; Large earthquakes
; Mainshock
; Post seismic
; Rupture areas
; Seismic deformation
; Slip model
; Global positioning system
; aftershock
; coseismic process
; deformation
; displacement
; earthquake magnitude
; earthquake rupture
; GPS
; seismic source
; seismology
; subduction zone
; Atacama
; Chile
; Copiapo
; Atacama
英文摘要: An earthquake sequence occurred in the Atacama region of Chile throughout September 2020. The sequence initiated by a mainshock of magnitude Mw= 6.9, followed 17 hours later by a Mw= 6.4 aftershock. The sequence lasted several weeks, during which more than a thousand events larger than Ml= 1 occurred, including several larger earthquakes of magnitudes between 5.5 and 6.4. Using a dense network that includes broad-band, strong motion and GPS sites, we study in details the seismic sources of the mainshock and its largest aftershock, the afterslip they generate and their aftershock, shedding light of the spatial temporal evolution of seismic and aseismic slip during the sequence. Dynamic inversions show that the two largest earthquakes are located on the subduction interface and have a stress drop and rupture times which are characteristics of subduction earthquakes. The mainshock and the aftershocks, localized in a 3D velocity model, occur in a narrow region of interseismic coupling (ranging 40%-80%), i.e. between two large highly coupled areas, North and South of the sequence, both ruptured by the great Mw∼8.5 1922 megathrust earthquake. High rate GPS data (1 Hz) allow to determine instantaneous coseismic displacements and to infer coseismic slip models, not contaminated by early afterslip. We find that the total slip over 24 hours inferred from precise daily solutions is larger than the sum of the two instantaneous coseismic slip models. Differencing the two models indicates that rapid aseismic slip developed up-dip the mainshock rupture area and down-dip of the largest aftershock. During the 17 hours separating the two earthquakes, micro-seismicity migrated from the mainshock rupture area up-dip towards the epicenter of the Mw 6.4 aftershocks and continued to propagate upwards at ∼ 0.7 km/day. The bulk of the afterslip is located up-dip the mainshock and down-dip the largest aftershock, and is accompanied with the migration of seismicity, from the mainshock rupture to the aftershock area, suggesting that this aseismic slip triggered the Mw= 6.4 aftershock. Unusually large post-seismic slip, equivalent to Mw= 6.8 developed during three weeks to the North, in low coupling areas located both up-dip and downdip the narrow strip of higher coupling, and possibly connecting to the area of the deep Slow Sleep Event detected in the Copiapo area in 2014. The sequence highlights how seismic and aseismic slip interacted and witness short scale lateral variations of friction properties at the megathrust. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165547
Appears in Collections: 气候变化与战略
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作者单位: Laboratoire de géologie, CNRS UMR 8538, Ecole normale supérieure, PSL University, Paris, France; Departamento de Geofísica, Universidad de Chile, Santiago, Chile; Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, F-75005, France; Institut Terre et Environnement de Strasbourg, Université de Str asbourg/EOST/ENGEES, CNRS UMR 7063, 5 rue Descartes, Strasbourg, F-67084, France; School of Earth and Ocean Sciences, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada; Université Côte d'Azur, IRD, CNRS, Observatoire de la Côte d'Azur, Géoazur, Sophia Antipolis, 250 rue Albert Einstein, Valbonne, 06560, France; Centro Sismológico Nacional Universidad de Chile, Blanco Encalada 2002, Santiago, CP 8370449, Chile
Recommended Citation:
Klein E.,Potin B.,Pasten-Araya F.,et al. Interplay of seismic and a-seismic deformation during the 2020 sequence of Atacama, Chile[J]. Earth and Planetary Science Letters,2021-01-01,570