Abstract
Summary The central Pamir plateau moves northward and collides into Eurasia at a rate that varies significantly over its 600 km-wide extension. However, the active structures accounting for such internal shear strain remain enigmatic. In this study, we use Interferometric Synthetic Aperture Radar (InSAR) data to investigate the coseismic and postseismic deformation of the ${M}_w6.9$ Sarez earthquake on 23 February 2023. Using a Bayesian framework, we find the most likely seismogenic fault geometry and explore the full solution space of slip distributions. Our results highlight the mainshock ruptures a nearly NNE fault dipping to the southeast. The finite-fault model exhibits a purely left-lateral strike-slip mechanism with little to no slip reaching the surface. Most of the coseismic slip remains confined to a depth of ∼5 to 20 km, consistent with a large shallow slip deficit. Postseismic afterslip, which decays rapidly within the month following the mainshock, cannot compensate for such coseismic shallow slip deficit. Integrating the analysis of coseismic slip, postseismic deformation, and regional seismic activity, we argue that in the central Pamir, significant north-south shear strain is accommodated along multiple parallel faults, often unmapped, hence posing a significant seismic hazard.
Published Version
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