Rupture termination at restraining bends: The last great earthquake on the Altyn Tagh Fault

Strike‐slip rupture propagation falters where changes in fault strike increase Coulomb failure stress. Numerical models of this phenomenon offer predictions of rupture extent based on bend geometry, but have not been verified with field data. To test model predictions of rupture barriers, we examine...

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Bibliographic Details
Published in:Geophysical research letters 2015-04, Vol.42 (7), p.2164-2170
Main Authors: Elliott, Austin J., Oskin, Michael E., Liu-Zeng, Jing, Shao, Yanxiu
Format: Article
Language:English
Subjects:
Alluvial fans
Altyn Tagh Fault
Barriers
Basins
Bend tests
Bends
Constraining
Coulomb friction
earthquake
Earthquakes
Escarpments
Failure
fault bend
Fault lines
Faults
Geological hazards
Geomorphology
Holocene
Mathematical models
Mountains
Numerical models
Offsets
Parameters
Plate tectonics
Pleistocene
Rupture
rupture barrier
rupture mechanics
Rupturing
Sedimentation & deposition
Seismic activity
Seismic hazard
Seismic phenomena
Seismology
Slip
Stress propagation
Strikes
surface rupture
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Summary:Strike‐slip rupture propagation falters where changes in fault strike increase Coulomb failure stress. Numerical models of this phenomenon offer predictions of rupture extent based on bend geometry, but have not been verified with field data. To test model predictions of rupture barriers, we examine rupture extent along a section of the sinistral Altyn Tagh Fault punctuated by three major double bends. We measure 3–8 m offsets and map >95 km of continuous scarps that define the most recent surface rupture. We document the eastern terminus of this rupture within the Aksay bend, where an undeformed Pleistocene alluvial fan we mapped and dated overlaps the fault. We conclude, based on this geomorphologic evidence, that multiple Holocene ruptures have stopped in the Aksay bend. Our field data validate model predictions of rupture termination at a >18° restraining bend and support use of geometric parameters to define expected earthquake sizes in seismic hazard models. Key Points The most recent rupture of the eastern Altyn Tagh Fault stopped at major bends No Quaternary fault rupture has propagated continuously through the Aksay bend Observations validate model result that >18 degree bends halt fault rupture
ISSN:0094-8276
1944-8007
DOI:10.1002/2015GL063107