Interactions of magmatic intrusions with the multiyear flank instability at Anak Krakatau volcano, Indonesia: Insights from InSAR and analogue modeling

Zorn, Edgar U and Vassileva, Magdalena and Walter, Thomas R. and Darmawan, Herlan and Röhler, Leonie and Amelung, Falk (2023) Interactions of magmatic intrusions with the multiyear flank instability at Anak Krakatau volcano, Indonesia: Insights from InSAR and analogue modeling. Geology, 51 (4). pp. 340-344. ISSN 00917613

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Abstract

Volcano flank collapses have been documented at ocean islands worldwide and are capable of triggering devastating tsunamis, but little is known about the precursory processes and deformation changes prior to flank failure. This makes the 22 December 2018 flank collapse at Anak Krakatau in Indonesia a key event in geosciences. Here, we provide direct insight into the precursory processes of the final collapse. We analyzed interferometric synthetic aperture radar (InSAR) data from 2014 to 2018 and studied the link between the deformation trend and intrusion occurrence through analogue modeling. We found that the flank was already moving at least 4 yr prior to collapse, consistent with slow décollement slip. Movement rates averaged ∼27 cm/yr, but they underwent two accelerations coinciding with distinct intrusion events in January/February 2017 and in June 2018. Analogue models suggest that these accelerations occurred by (re)activation of a décollement fault linked to a short episode of magma intrusion. During intrusion, we observed a change in the internal faults, where the outward-directed décollement accelerated while inward faults became partially blocked. These observations suggest that unstable oceanic flanks do not disintegrate abruptly, but their collapse is preceded by observable deformations that can be accelerated by new intrusions.

Item Type: Article
Uncontrolled Keywords: decollement; deformation mechanism; igneous intrusion; magmatic differentiation; satellite data; satellite imagery; synthetic aperture radar; volcanology
Subjects: Q Science > QC Physics
Divisions: Faculty of Mathematics and Natural Sciences > Physics Department
Depositing User: Ismu WIDARTO
Date Deposited: 24 Sep 2024 05:16
Last Modified: 24 Sep 2024 05:16
URI: https://ir.lib.ugm.ac.id/id/eprint/7481

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