Karstens, Jens , Urlaub, Morelia and Berndt, Christian (2022) State of the art in the study of volcanic flank collapses. [Talk] In: International Conference on Seafloor Landforms, Processes and Evolution. , 04.06.2022-06.06.2022, Valetta, Malta .

Abstract

Gravitational forces act on the steep and commonly
unstable flanks of volcanoes. This can lead to flank
deformation on a variety of temporal and spatial
scales ranging from slow creep to catastrophic sector
collapse. The catastrophic collapse of the volcano
Anak Krakatau in the Sunda Strait (Indonesia) on 22
December 2018 caused a tsunami with >400 fatalities.
The largest part of coastal and ocean island volcanoes,
as well as the remnants of their past collapses, are
often below sea level. Using examples from different
volcanoes worldwide, we show how seafloor
morphology, geophysical imaging, seafloor geodesy,
and numerical modelling can help to reconstruct past
flank collapses and to understand the present state of
unstable volcano flanks. From these observations, we
propose that flank collapse involves two processes that
are potentially linked: large-scale slow flank sliding on
a deep detachment (the interface to the pre-volcano
basement) and catastrophic collapse of a fraction of
the sliding flank along a shallower failure surface. Better
understanding of this link is crucial for assessing the
hazard associated with the numerous marine or coastal
volcanoes worldwide that are known to have seaward-
sliding flanks

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