Satellite datasets capture forest disturbance and recovery patterns from
explosive volcanic eruption
Abstract
The characteristics and extent of forest damage and subsequent patterns
of recovery reflect the intensity of an explosive volcanic eruption and
have the potential to be a novel proxy for eruption magnitude and
impact. Using vegetation damage and recovery patterns following the 2015
explosive eruption of Calbuco, Chile, we develop a satellite-based
approach to assess impact on surrounding temperate forests. The Calbuco
eruption resulted in tephra deposition over 100skm2, pyroclastic flows
extending 6km and lahars extending 15km. We explore NDVI derived from
optical imagery (June 2013 - May 2023) as well as radar backscatter and
phase coherence (October 2014 - June 2023) through time series analysis,
clustering and estimation of recovery timescales to find patterns in
forest disturbance and recovery. We find that forest damage and recovery
correspond primarily with deposit type, thickness and dispersal
directions. The thickest tephra deposits (> 40cm) correlate
with the most vegetation loss, so our vegetation impact maps allow us to
refine the spatial mapping of tephra fall-deposit isopachs to give a
revised eruption volume of 0.28km3. Vegetation recovery rates relate to
initial impact intensity, but also local topography, aspect and
altitude. Our results demonstrate the potential of vegetation
disturbance as a novel proxy that can be used to determine eruption
extents and magnitudes, especially in remote and densely vegetated
environments, and to refine field-based analyses in inaccessible or
intensely damaged zones.