Coseismic landslides are a major hazard associated with large
earthquakes in mountainous regions. Despite growing evidence for their
widespread impacts and persistence, current understanding of the
evolution of landsliding over time after large earthquakes, the hazard
that these landslides pose, and their role in the mountain sediment
cascade remains limited. To address this, we present the first
systematic multi-temporal landslide inventory to span the full rupture
area of a large continental earthquake across the pre-, co-and
post-seismic periods. We focus on the 3.5 years since the 2015 Mw 7.8
Gorkha earthquake in Nepal and show that throughout this period both the
number and area of mapped landslides have remained higher than on the
day of the earthquake itself. We document systematic upslope and
northward shifts in the density of landsliding through time. Areas where
landslides have persisted tend to cluster in space, but those areas that
have returned to pre-earthquake conditions are more dispersed. Whilst
both pre-and coseismic landslide locations tend to experience persistent
post-earthquake landsliding, a wider population of newly activated but
spatially-dispersed landslides has developed after the earthquake. This
is particularly important for post-earthquake recovery plans that are
typically based on hazard assessments conducted immediately
post-earthquake and thus do not consider the evolving landslide hazard.
We show that recovery back to pre-earthquake landsliding rates is
fundamentally dependent on how that recovery is defined and measured.
Clarity around this definition is particularly important for informing a
comprehensive and precautionary approach to post-earthquake landslide
hazard and risk.