The 2018-2019 seismo-volcanic crisis offshore Mayotte: depletion of a deep offshore magmatic reservoir
Abstract
A complex seismic sequence has affected a region offshore Mayotte Island, in the Northern Mozambique channel, since May 2018. Seismic signals include a swarm of volcano-tectonic (VT) earthquakes and energetic, long-lasting very long period (VLP) signals. The seismic sequence was accompanied by a large surface deflation, recorded by multiple GNSS stations at Mayotte Island. The deflation confirms the volcanic origin of the sequence and points at the depletion of a large and deep reservoir. We use local and regional seismic data, teleseismic seismic data and the GNSS data at Mayotte to reconstruct the complex magmatic process and the mechanical response of the Earth's crust to magma transport and drainage. We identified and characterized thousands of VTs and hundreds of VLPs that suggest a sequence of processes including propagation of a magmatic dike, sea floor eruption and reservoir depletion. The first stage of the process involved upward and lateral migration of VTs, suggesting ascent of a magmatic dike, which opened a path for the magma to the seafloor, where a new submarine volcano was recently discovered. In a second phase, VTs changed location and focal mechanisms, suggesting brittle weakening in the reservoir overburden. VLPs suggest the resonance of a sub-horizontal magmatic body, with a diameter of ~10-15 km.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V52D..04C
- Keywords:
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- 8499 General or miscellaneous;
- VOLCANOLOGY