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Monitoring long-term deformation of coastal volcanoes in Southeast Asia with Sentinel-1 InSAR

Edgar U. Zorn1,2 , Falk Amelung3, Francesco Massimetti4, Marco Laiolo4, Diego Coppola4, Yan Lavallée1, Thomas R. Walter2, Herlan Darmawan5

  • Affiliations: 1Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München, Germany; 2GFZ Helmholtz Centre for Geosciences, Helmholtzstraße 6/7, 14467 Potsdam, Germany; 3Department of Marine Geosciences, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA; 4Department of Earth Sciences, University of Torino, Via Valperga Caluso 35, 10125 Turin, Italy; 5Laboratory of Geophysics, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, 55281, Yogyakarta, Indonesia 

  • Presentation type: Talk

  • Presentation time: Tuesday 14:45 - 15:00, Room R290

  • Programme No: 6.3.3

  • Theme 6 > Session 3

Abstract

Deformation of volcanoes and their flanks is a ubiquitous process at many volcanoes worldwide but presents a major concern due to the potential of flank instabilities and collapse. This is particularly relevant for volcanoes near the coast as such a collapse into the sea could trigger a far-reaching tsunami. We collected multi-year Sentinel-1 InSAR data to investigate surface deformation of 18 near-sea volcanoes in Southeast Asia with the aim to identify potential flank instability and tsunamigenic potential. We further correlate this with the volcanic activity measured by the volcanic radiative power (VRP) and reported periods of unrest or eruptions. We find that over 80% of the studied volcanoes exhibit signs of persistent or episodic surface deformation, in most cases expressed as Line-of-Sight (LOS) increase reflecting subsidence and/or slope movement with large variability in spatial extent and displacement rates, ranging from mm/yr to dm/yr. In multiple cases, subsidence is likely associated with gravitational processes that imply flank instability. We highlight likely ongoing flank instability at Anak Krakatau and Ulawun, and present results for multiple other volcanoes showing potential signs of gravity-driven movements, though data coverage is often insufficient to be conclusive. Additionally, we identify multiple cases where deformation rates appeared to accelerate in direct response to increased volcanic activity or eruptions and remaining elevated for several years after. This data offers key insights into the spatio-temporal scales of volcano deformation in Southeast Asia and reveals a direct link to eruptive activity, which may facilitate flank instability and potential collapse hazards.