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Abstract:
Volcanic eruptions are often preceded by episodes of inflation and emplacement of magma along tensile fractures, forming dikes or sills. Here, we present evidence for crater alignments and for a complex tensile fracture dissecting part of the eruption cone, during the very late stages of the Cumbre Vieja eruption. We use satellite radar amplitude image observations, together with photogrammetrically processed drone and time-lapse camera data, to determine scale and complexities associated with the late fracturing event. In a rapid response task force we acquired in-situ data, which we complement by the use of analog models to show that formation of the tensile fractures are strongly influenced by topography, diverging at topographic highs and converging at topographic lows. The observations at the late eruption phase and from our models are of importance for understanding tensile fracture sets at the already pronounced volcano topography of La Palma, and allow speculation of a shallow topographic driver responsible for a localized dike propagation.
