Seismic evidence of multi-stage volcanic flank collapse and refined deposit volume offshore Fogo, Cabo Verde
Abstract
Gravitational volcanic flank collapses are recurrent processes producing large-scale landslides, commonly associated with secondary instabilities and destructive tsunamis. Ocean island volcanoes are particularly prone to such failures, yet the dynamics, emplacement mechanisms, and tsunamigenic potential of gravitational collapses remain poorly constrained due to the scarcity of direct observations. The ~ 68 ka Monte Amarelo flank collapse at Fogo, Cabo Verde, is one of the prominent examples of tsunamigenic gravitational collapses globally. But key parameters, including the collapse volume and the number of collapse stages, remain debated. We identify an extensive (914 km2) debris avalanche deposit associated with the Monte Amarelo volcanic flank collapse using high-resolution multibeam bathymetry and multichannel seismic reflection data. In addition, we find a smaller, previously unknown debris avalanche deposit superimposed on the northern half of the main deposit. Our results indicate that the Monte Amarelo collapse involved up to ~ 98 km3 of material—the first volume estimate constrained by direct imaging of the submarine debris avalanche deposit through seismic data. The local morphology and internal structure of the main deposit suggest rapid emplacement and high tsunamigenic potential. The presence of a second deposit indicates multiple stages of collapse. Our results provide new constraints on the dynamics, volume, and sequence of events of one of the most recent gravitational collapses of a volcanic island in the Atlantic. These findings have important implications for tsunami generation and modelling and contribute to an improved understanding of hazards associated with gravitational collapses of volcanic islands.
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BibTeX
@article{hadre2026seismic,
title = {{Seismic evidence of multi-stage volcanic flank collapse and refined deposit volume offshore Fogo, Cabo Verde}},
author = {Emma Hadré and Elodie Lebas and Ricardo S Ramalho and Henrik Grob and Rui Quartau and Rachel Barrett and Janne M Scheffler and Ingo Klaucke and Steffen Kutterolf and Sebastian Krastel},
journal = {Bulletin of Volcanology},
year = {2026},
month = jul,
doi = {10.1007/s00445-026-02014-3},
url = {https://hal.science/hal-05743732v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Seismic evidence of multi-stage volcanic flank collapse and refined deposit volume offshore Fogo, Cabo Verde
AU - Emma Hadré
AU - Elodie Lebas
AU - Ricardo S Ramalho
AU - Henrik Grob
AU - Rui Quartau
AU - Rachel Barrett
AU - Janne M Scheffler
AU - Ingo Klaucke
AU - Steffen Kutterolf
AU - Sebastian Krastel
PY - 2026
DA - 2026/07/11
JO - Bulletin of Volcanology
DO - 10.1007/s00445-026-02014-3
UR - https://hal.science/hal-05743732v1
AB - Gravitational volcanic flank collapses are recurrent processes producing large-scale landslides, commonly associated with secondary instabilities and destructive tsunamis. Ocean island volcanoes are particularly prone to such failures, yet the dynamics, emplacement mechanisms, and tsunamigenic potential of gravitational collapses remain poorly constrained due to the scarcity of direct observations. The ~ 68 ka Monte Amarelo flank collapse at Fogo, Cabo Verde, is one of the prominent examples of tsunamigenic gravitational collapses globally. But key parameters, including the collapse volume and the number of collapse stages, remain debated. We identify an extensive (914 km2) debris avalanche deposit associated with the Monte Amarelo volcanic flank collapse using high-resolution multibeam bathymetry and multichannel seismic reflection data. In addition, we find a smaller, previously unknown debris avalanche deposit superimposed on the northern half of the main deposit. Our results indicate that the Monte Amarelo collapse involved up to ~ 98 km3 of material—the first volume estimate constrained by direct imaging of the submarine debris avalanche deposit through seismic data. The local morphology and internal structure of the main deposit suggest rapid emplacement and high tsunamigenic potential. The presence of a second deposit indicates multiple stages of collapse. Our results provide new constraints on the dynamics, volume, and sequence of events of one of the most recent gravitational collapses of a volcanic island in the Atlantic. These findings have important implications for tsunami generation and modelling and contribute to an improved understanding of hazards associated with gravitational collapses of volcanic islands.
SN - 0258-8900
SN - 1432-0819
ER -