Normal faults and tectonic model of the Bamei-Kangding segment within the southern Xianshuihe fault zone in Eastern Tibet
Author(s)
Type
Journal Article
Abstract
The left-lateral strike-slip Xianshuihe fault (XSHF) located in the eastern Tibetan Plateau is considered one of the most tectonically active intra-continental faults in China. Despite extensive research on the XSHF, the detailed late Quaternary slip rates of secondary faults and mechanisms for significant normal faulting observed within the Bamei-Kangding segment remain poorly understood. Through integrated analysis of satellite imagery, field surveys, and small Unmanned Aerial Vehicle photogrammetry-derived Digital Elevation Models, coupled with multiple dating methods (10Be Terrestrial Cosmogenic Nuclide and Optically Stimulated Luminescence) to date moraines offset by the faults, we reveal a unique tectonic setting where the left-stepping NW Xianshuihe fault and Moxi fault create a releasing stepover that accommodates right-stepping secondary faults and explains normal faulting. The 24-km-long Mugecuo fault is characterized by two primary branches (southern and northern), with sinistral slip rates of 1.2 ± 0.1 mm/yr and 1.1 ± 0.1 mm/yr, and vertical slip rates of 0.1 mm/yr and 0.8 ± 0.1 mm/yr, respectively. The Zheduotang fault exhibits distinct segmentation with its northwestern segment showing a higher sinistral slip rate of 6.7 ± 1.4 mm/yr compared to its southeastern segment. These newly constrained slip rates indicate a strike-slip-dominated system with subordinate normal faulting and progressive strain migration toward a more geometrically smooth configuration. The secondary faults vertically connect to form a negative flower structure, elevating cascading rupture potential. Fresh scarps along the Mugecuo fault may be related to the 1725 M 7.0 Kangding earthquake, highlighting significant seismic hazard implications for this region.
Date Issued
2025-10-01
Date Acceptance
2025-09-24
Citation
Tectonics, 2025, 44 (10)
ISSN
0278-7407
Publisher
Wiley
Journal / Book Title
Tectonics
Volume
44
Issue
10
Copyright Statement
Copyright © 2025. American Geophysical Union. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Subjects
ACTIVE FAULT
cosmogenic nuclide dating
DEFORMATION
EARTHQUAKE SEQUENCE
Geochemistry & Geophysics
HIGH-RESOLUTION
HOLOCENE
MONSOON RECORD
normal faulting
NUCLIDE PRODUCTION-RATES
Physical Sciences
QUATERNARY SLIP-RATE
releasing stepover
Science & Technology
slip rate
Tibetan Plateau
TOPOGRAPHY
WESTERN SICHUAN
Xianshuihe Fault
Publication Status
Published
Article Number
e2025TC008925
Date Publish Online
2025-10-09