Mountain resonance shapes the distribution of earthquake-induced landslides

TL;DR

This study reveals that mountain-scale resonance significantly influences the distribution and size of earthquake-induced landslides, emphasizing an overlooked physical mechanism in hazard assessment.

Contribution

It demonstrates that mountain resonance frequencies control landslide occurrence and size, integrating modal analysis with landslide data to reveal a new physical mechanism.

Findings

Landslides occur on mountains with resonant frequencies overlapping earthquake frequencies.

Affected mountains have systematically lower resonant frequencies than stable ones.

Larger landslides are associated with lower-frequency mountains.

Abstract

Earthquake-induced landslides are among the most destructive cascading hazards, yet the physical mechanisms governing their spatial distribution and size remain incompletely understood. While amplification of seismic waves by local topography is well documented, the role of mountain-scale resonance has remained largely untested. Here we demonstrate that the resonant frequency of mountains exerts a statistically significant control on the occurrence, spatial pattern, and size of coseismic landslides. Using the 2015 Mw 7.8 Gorkha earthquake in Nepal, which triggered more than 25,000 landslides, we combine three-dimensional modal analysis of 3,130 mountain bodies with a high-resolution landslide inventory. Landslides preferentially occur on mountains whose resonant frequencies (0.5-1.2 Hz) overlap with the dominant frequency content of the earthquake. Mountains affected by landslides exhibit systematically lower resonant frequencies than stable mountains, and larger landslides are associated with lower-frequency mountains. These findings provide quantitative evidence that mountain-scale resonance amplifies seismic ground motion sufficiently to influence landslide triggering, highlighting an overlooked mechanism that should be incorporated into assessments of earthquake-induced landslide hazard.