DOI: 10.1016/j.epsl.2018.05.020
Scopus记录号: 2-s2.0-85047423114
论文题名: Fault behavior and lower crustal rheology inferred from the first seven years of postseismic GPS data after the 2008 Wenchuan earthquake
作者: Diao F. ; Wang R. ; Wang Y. ; Xiong X. ; Walter T.R.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 495 起始页码: 202
结束页码: 212
语种: 英语
英文关键词: afterslip
; postseismic deformation
; seismic hazard
; viscoelastic relaxation
; Wenchuan earthquake
Scopus关键词: Deformation
; Elasticity
; Faulting
; Geodetic satellites
; Global positioning system
; Viscoelasticity
; afterslip
; Postseismic deformation
; Seismic hazards
; Viscoelastic relaxation
; Wenchuan Earthquake
; Earthquakes
; complexity
; crustal deformation
; earthquake mechanism
; fault slip
; GPS
; lithospheric structure
; postseismic process
; rheology
; seismic hazard
; seismic velocity
; Sichuan earthquake 2008
; viscoelasticity
; China
; Qinghai-Xizang Plateau
; Sichuan Basin
英文摘要: Long-term and wide-area geodetic observations may allow identifying distinct postseismic deformation processes following large earthquakes, and thus can reveal fault behavior and permit quantifying complexities in lithospheric rheology. In this paper, the first 7 years of GPS (Global Positioning System) displacement data following the 2008 Mw7.9 Wenchuan earthquake are used to study the relevant mechanisms of postseismic deformation. Two simple models that consider either afterslip or viscoelastic relaxation as the unitary mechanism of the postseismic deformation are tested at first. After analyzing the limitations and complementarity of these two separated models, a combined model incorporating the two main mechanisms is presented. In contrast to previous studies, which mostly assume that afterslip and viscoelastic relaxation are independent, our combined model includes the secondary viscoelastic relaxation effect induced by transient afterslip. Modeling results suggest that the middle- to far-field postseismic deformation is mainly induced by viscoelastic relaxation of the coseismic stress change in the lower crust, whereas the near-field displacement is dominantly caused by stress-driven aseismic afterslip. The seismic moment released by the transient afterslip corresponds to an Mw7.4 earthquake, or 25% of that released by the Mw7.9 main shock. With a characteristic decay time of 1.2 yr, most afterslip (∼80%) is released in the first 2 years. Negligible aseismic afterslip is observed in the seismic gap between the Wenchuan and Lushan earthquakes, indicating the locked state of the fault within this segment. The effective lower crustal viscosity of the eastern Tibetan Plateau is estimated to be 2.0×1018Pas, at least two orders of magnitude smaller than that of the adjacent Sichuan Basin. This finding is consistent with previous observations of low seismic velocity and high electrical conductivity in this region, all of which support the assumption that the crustal thickening in the eastern Tibetan Plateau is dominantly caused by ductile lower crustal flow, with important implications for understanding both long- and short-term crustal deformation processes. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109817
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan, 430074, China; GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, D-14473, Germany; National Earthquake Infrastructure Service, Beijing, 100045, China
Recommended Citation:
Diao F.,Wang R.,Wang Y.,et al. Fault behavior and lower crustal rheology inferred from the first seven years of postseismic GPS data after the 2008 Wenchuan earthquake[J]. Earth and Planetary Science Letters,2018-01-01,495