Three-dimensional anisotropy of seismite deformation constrains seismogenic fault location

Earthquake ground motion is inherently directional and governs deformation in near-surface sediments, yet whether this directional information is preserved in geological archives remains poorly constrained. Soft-sediment deformation structures produced by earthquakes (seismites) are widely used to reconstruct past earthquake catalogues but are generally assumed to lack information on seismic-wave direction, limiting their ability to identify seismogenic faults. Here we develop a three-dimensional physical framework integrating numerical simulations with field observations to resolve how different seismic-wave components control deformation anisotropy in water-saturated sediments. We show that horizontally polarized shear waves dominate anisotropic deformation, producing systematically stronger shear and folding on planes oriented perpendicular to wave propagation. This behaviour is quantified using a dimensionless deformation index and fold counts measured on orthogonal profiles. Applying this framework to a well-preserved three-dimensional seismite in the Pamir region, we demonstrate that contrasts in deformation intensity robustly record seismic source direction and enable identification of causative seismogenic faults, together with reconstruction of a sequence of paleo-earthquakes when integrated with chronological constraints. These results establish that near-surface geological deformation can preserve directional information on seismic-wave propagation, opening new opportunities to reconstruct seismic source direction from sedimentary cores and outcrop-scale geological records worldwide.