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Strain Accommodation Along the Northeast Altyn Tagh Fault System and the Potential for a Future Large-Magnitude, Multi-Fault Rupture

Description: 

Large continental strike-slip fault systems typically comprise a principal displacement zone and subordinate splay faults, exhibiting complex geometry and variations in fault distribution. Understanding the architecture, interconnections, and synchronous rupture patterns of these faults is crucial for comprehending their tectonic evolution, strain distribution, and earthquake behavior. Here we provide a comprehensive analysis of Quaternary deformation, interconnection, and late Holocene ruptures along the EW-trending Nanjieshan Fault (NJSF), a major branch fault of the Altyn Tagh Fault (ATF) system. The calculated strike-slip rate of the master NJSF is ~0.5 mm/a since ~45 ka, consistent with the low slip rates observed on other faults NW of the ATF. Moreover, the NJSF may have experienced an exceptionally high slip rate since the late Pleistocene, implying a potential change in fault strain distribution along the northern ATF. New trench data across the NJSF reveals three surface-rupturing events in the last 2500 years. Significantly, these millennium-scale events coincide temporally with the last two major earthquakes documented on the principal ATF, suggesting quasi-simultaneous rupture behavior. We conclude that accurate evaluation of paleoearthquake magnitudes and potential rupture behavior on major continental strike-slip fault systems should include field studies of both the principal fault and subordinate branching faults.

Session: Learning Across Geological, Geophysical & Model-Derived Observations to Constrain Earthquake Behavior - I

Type: Oral

Date: 5/1/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Haibo

Student Presenter: No

Invited Presentation: 

Authors