DOI: 10.1016/j.tecto.2020.228366
论文题名: Constraints on the shallow deformation around the Main Frontal Thrust in central Nepal from refraction velocities
作者: Liu Y. ; Hubbard J. ; Almeida R.V. ; Foster A. ; Liberty L. ; Lee Y.S. ; Sapkota S.N.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 777 语种: 英语
中文关键词: Main Frontal Thrust
; Nepal Himalaya
; P-wave velocity
; Sediment thickness
; Seismic refraction
; Water table
英文关键词: Refraction
; Seismic waves
; Seismology
; Velocity
; Wave propagation
; Himalayas
; Main Frontal Thrust
; P-wave velocity
; Sediment thickness
; Seismic refraction
; Water tables
; Groundwater
; deformation
; earthquake event
; Himalayan orogeny
; P-wave
; sediment thickness
; seismic refraction
; seismic velocity
; thrust fault
; water table
; wave velocity
; Nepal
英文摘要: The youngest fault system in the Himalayan orogeny is the Main Frontal Thrust (MFT), the frontal ramp of the Main Himalayan Thrust, which is expected to host the largest and most damaging earthquakes in Nepal. We characterize the upper few hundred meters below the surface across two MFT fault strands using ten high-resolution seismic profiles that we acquired in 2014 and 2015 with a 6-tonne Vibroseis source. We use first arrival picks from 625,416 seismic traces to derive P-wave seismic velocity models using a wavepath eikonal traveltime inversion method, and derive estimates of alluvium thickness and water table depth across these faults (the Patu and Bardibas thrusts), allowing us to constrain the subsurface geometry of the MFT. Our results show that 1) seismic velocities range from 255 to 3660 m/s, consistent with dry and saturated alluvium, and Siwalik bedrock; 2) low-velocity alluvium varies between ~20–50 and ~80–120 m thick in the hanging wall and footwall of the Bardibas thrust, respectively, corresponding to ~60–70 m of uplift of the hanging wall since deposition; 3) the two thrusts are soft-linked, and the western tip of the Bardibas thrust lies ~6 km west of its surface expression; 4) during the dry season, the water table is ~25–100 m higher in the hanging walls of the faults than in their footwalls, due to the larger thickness of permeable alluvium in the footwalls, and the water table shallows towards the east in the hanging wall of the Bardibas thrust; and 5) consistent with previous studies, the Patu thrust breaches the surface, while the Bardibas thrust is blind at Ratu Khola. These results also demonstrate that it should be possible to constrain the rate of uplift above the Bardibas thrust by drilling and dating sediments on both sides, which would complement existing measurements from terrace uplift. © 2020 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170649
Appears in Collections: 气候变化与战略
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作者单位: Asian School of the Environment, Nanyang Technological University, 50 Nanyang Ave., Singapore, 639798, Singapore; Earth Observatory of Singapore, Nanyang Technological University, 50 Nanyang Ave., Singapore, 639798, Singapore; Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, Canada; Department of Geosciences, Boise State UniversityID, United States; Department of Mines and Geology, Kathmandu, 44600, Nepal; School of Earth Science, Energy and Environment, Yachay Tech University, Ecuador
Recommended Citation:
Liu Y.,Hubbard J.,Almeida R.V.,et al. Constraints on the shallow deformation around the Main Frontal Thrust in central Nepal from refraction velocities[J]. Tectonophysics,2020-01-01,777