气候变化领域集成服务门户(CCPortal): Postseismic Deformation Following the 2015 M(w)7.8 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 M(w)7.8 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.
通讯作者	Rollins, C (通讯作者)
发表日期	2020
ISSN	2169-9313
EISSN	2169-9356
卷号	125 期号:9
英文摘要	We report Global Positioning System (GPS) measurements of postseismic deformation following the 2015 M(w)7.8 Gorkha (Nepal) earthquake, including previously unpublished data from 13 continuous GPS stations installed in southern Tibet shortly after the earthquake.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)sigma 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 similar to 3.10(16)-3.10(17) Pa.s over the first 1.12 postseismic years. Near-field deformation can be more plausibly explained by afterslip itself and implies (a - b)sigma similar to 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.
关键词	W 7.8 GORKHA EASTERN HIMALAYAN SYNTAXIS TIBETAN PLATEAU CRUSTAL DEFORMATION VELOCITY-FIELD FAULT RHEOLOGY BENEATH BASIN CONSTRAINTS
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000577119500006
来源期刊	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/260046
推荐引用方式 GB/T 7714	Liu-Zeng, J.,Zhang, Z.,Rollins, C.,et al. Postseismic Deformation Following the 2015 M(w)7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation[J]. 中国科学院青藏高原研究所,2020,125(9).
APA	Liu-Zeng, J..,Zhang, Z..,Rollins, C..,Gualandi, A..,Avouac, J. -P..,...&Li, Z..(2020).Postseismic Deformation Following the 2015 M(w)7.8 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 M(w)7.8 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).