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Satellite datasets capture forest disturbance and recovery patterns from explosive volcanic eruption
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  • Megan L Udy,
  • Susanna K Ebmeier,
  • Sebastian Watt,
  • Andrew Hooper,
  • Alberto Parades
Megan L Udy
University of Leeds

Corresponding Author:[email protected]

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Susanna K Ebmeier
University of Leeds
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Sebastian Watt
University of Birmingham
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Andrew Hooper
University of Leeds
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Alberto Parades
Universidad Austral de Chile
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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.
22 May 2024Submitted to ESS Open Archive
28 May 2024Published in ESS Open Archive