Estimating Hillslope-Scale Topographic Amplification from Space

Abstract

Topographic amplification (TA) alters seismic-wave propagation and can intensify ground shaking and earthquake damage. Yet observational assessments of TA remain largely constrained to hillslope and regional scales, and spatially varying TA footprints are still documented primarily through earthquake simulations rather than direct observations. Here, we present an observation-driven approach to estimate TA across contrasting tectonic settings using InSAR-derived coseismic displacement fields from nine earthquakes (Mw 6.0–7.8), with strike-slip, thrust, and normal-fault events equally represented. We quantified TA for each hillslope as the relative increase in coseismic deformation in its upper section compared with its lower section across all sites. These observational patterns were then evaluated with numerical earthquake simulations to address the key limitation of using coseismic displacement as a proxy for amplification in ground shaking. Overall, this work aims to numerically assess how topographic amplification varies across earthquake mechanisms and space.