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Evidence of mass-wasting and large flank-collapse at Fogo, Cape Verde: New insights from marine geophysical data

Emma Hadré 1, Elodie Lebas2, Janne Scheffler3, Elisa Klein3, Rachel Barrett1,4, Andreas Klügel5, Steffen Kutterolf3, Ricardo Ramalho6, Morelia Urlaub3, Sebastian Krastel1

  • Affiliations: 1Institute of Geosciences, Christian-Albrechts-Universität zu Kiel, Kiel, Germany; 2Université Paris Cité, Institut de Physique du Globe de Paris, Paris, France; 3GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany; 4Monterey Bay Aquarium Research Institute, Moss Landing, USA; 5Faculty of Geosciences, University of Bremen, Bremen, Germany; 6School of Earth and Environmental Sciences, Cardiff University, Cardiff, UK

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 156

  • Programme No: 2.2.20

  • Theme 2 > Session 2

Abstract

Gravitational instabilities are recurrent processes affecting volcanic islands during their lifetime. Flank collapses, as a result of instability, can trigger secondary failures and tsunamis that may cause damage to coastal and offshore infrastructure. A complex history of mass-wasting events has been described in the Cape Verde Archipelago using marine geophysical datasets, including the ca. 73 ka Monte Amarelo flank collapse at Fogo which triggered a mega-tsunami. To better understand the emplacement of the submarine Monte Amarelo debris avalanche deposits and the interplay between landslides, intrusions and volcanism, we investigated high-resolution multichannel seismic (MCS) reflection data gathered in 2019 during the research cruise M155 onboard R/V METEOR. The internal architecture of the Monte Amarelo deposits as captured by the MCS data, in combination with high-resolution bathymetric data, allows precise estimates of their volume and extent and helps us to decipher its emplacement and impact on pre-existing sediments. MCS data covering Fogo's southern volcaniclastic apron show multiple mass-wasting events coinciding with volcanic intrusions and associated faulting. These deposits are predominantly located above high-amplitude reflector packages, which we interpret to represent increased input of volcaniclastic material. In combination with ongoing work on sediment cores, we aim to establish a chronological timeframe of landslide processes in the Cape Verde Archipelago and estimate recurrence periods. Our results contribute to the understanding of flank collapse and mass-wasting at volcanic islands, and their relation to tectonic and volcanic activity, along with improving hazard assessments and monitoring at unstable volcanoes.