Quaternary rupture behavior of the Karakoram Fault and its relation to the dynamics of the continental lithosphere, NW Himalaya–western Tibet

• The Karakoram Fault displays variable seismic activity at the millennial scale.
• We define the instantaneous slip rate (ISR).
• Seismic activity on the subducting Indian plate may modulate stress along the Karakoram Fault.

The Karakoram Fault is a major strike-slip system that partitions strain between the compressional regime of the NW Himalaya and the translational and extensional fault systems of western Tibet. Although seismic and geodetic observations suggest that the fault is currently locked, a high millennial slip rate infers a dominant role in the deformation of western Tibet. We examine all Quaternary data available for the Karakoram Fault and attempt to explain the temporal and spatial variability of fault slip rate. We show that the Karakoram Fault stress level could be modulated by Coulomb stress changes associated with varying seismicities on the subducting Indian plate beneath western Tibet. Our model has implications for the understanding of stress transfer between large fault systems and their interaction with lithosphere deformation. We suggest that while the long-term deformation of Tibet may be modeled as a partially viscous medium, the slip rates of major faults may vary by one order of magnitude during the Quaternary. Our analysis may resolve the frequently observed discrepancy between millennial and decadal records of fault slip rates.