气候变化领域集成服务门户(CCPortal): Postseismic Deformation Following the 2015 Mw7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation

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DOI	10.1029/2020JB019852
	Postseismic Deformation Following the 2015 Mw7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation
	Liu-Zeng J.; Zhang Z.; Rollins C.; Gualandi A.; Avouac J.-P.; Shi H.; Wang P.; Chen W.; Zhang R.; Zhang P.; Wang W.; Li Y.; Wang T.; Li Z.
发表日期	2020
ISSN	21699313
卷号	125 期号:9
英文摘要	We report Global Positioning System (GPS) measurements of postseismic deformation following the 2015 Mw7.8 Gorkha (Nepal) earthquake, including previously unpublished data from 13 continuous GPS stations installed in southern Tibet shortly after the earthquake. We use variational Bayesian Independent Component Analysis (vbICA) to extract the signal of postseismic deformation from the GPS time series, revealing a broad displacement field extending >150 km northward from the rupture. Kinematic inversions and dynamic forward models show that these displacements could have been produced solely by afterslip on the Main Himalayan Thrust (MHT) but would require a broad distribution of afterslip extending similarly far north. This would require the constitutive parameter (a − b)σ to decrease northward on the MHT to ≤0.05 MPa (an extreme sensitivity of creep rate to stress change) and seems unlikely in light of the low interseismic coupling and high midcrustal temperatures beneath southern Tibet. We conclude that the northward reach of postseismic deformation more likely results from distributed viscoelastic relaxation, possibly in a midcrustal shear zone extending northward from the seismogenic MHT. Assuming a shear zone 5–20 km thick, we estimate an effective shear-zone viscosity of ~3·1016–3·1017 Pa·s over the first 1.12 postseismic years. Near-field deformation can be more plausibly explained by afterslip itself and implies (a − b)σ ~ 0.5–1 MPa, consistent with other afterslip studies. This near-field afterslip by itself would have re-increased the Coulomb stress by ≥0.05 MPa over >30% of the Gorkha rupture zone in the first postseismic year, and deformation further north would have compounded this reloading. © 2020. American Geophysical Union. All Rights Reserved.
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187594
作者单位	State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing, China; Institute of Surface Earth System Science, Tianjin University, Tianjin, China; Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China; School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States; China Earthquake Networks Center, Beijing, China; Department Research Center of China Earthquake Administration, Beijing, China
推荐引用方式 GB/T 7714	Liu-Zeng J.,Zhang Z.,Rollins C.,et al. Postseismic Deformation Following the 2015 Mw7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation[J],2020,125(9).
APA	Liu-Zeng J..,Zhang Z..,Rollins C..,Gualandi A..,Avouac J.-P..,...&Li Z..(2020).Postseismic Deformation Following the 2015 Mw7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation.Journal of Geophysical Research: Solid Earth,125(9).
MLA	Liu-Zeng J.,et al."Postseismic Deformation Following the 2015 Mw7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation".Journal of Geophysical Research: Solid Earth 125.9(2020).