Direct observation of degassing during decompression of basaltic magma
Transitions in eruptive style during volcanic eruptions strongly depend on how easily gas and magma decouple during ascent. Stronger gas-melt coupling favors highly explosive eruptions, whereas weaker coupling promotes lava fountaining and lava flows. The mechanisms producing these transitions are still poorly understood because of a lack of direct observations of bubble dynamics under natural magmatic conditions. Here, we combine x-ray radiography with a novel high-pressure/high-temperature apparatus to observe and quantify in real-time bubble growth and coalescence in basaltic magmas from 100 megapascals to surface. For low-viscosity magmas, bubbles coalesce and recover a spherical shape within 3 seconds, implying that, for lava fountaining activity, gas and melt remain coupled during the ascent up to the last hundred meters of the conduit. For higher-viscosity magmas, recovery times become longer, promoting connected bubble pathways. This apparatus opens frontiers in unraveling magmatic/volcanic processes, leading to improved hazard assessment and risk mitigation.
Authors
- Robert Atwood (ORCID: https://orcid.org/0000-0001-6708-1085)
- Jonathan Fellowes (ORCID: https://orcid.org/0009-0008-7224-537X)
- Barbara Bonechi (ORCID: https://orcid.org/0000-0002-0242-4320)
- Jean‐Louis Hazemann (ORCID: https://orcid.org/0000-0002-3717-2151)
- Fabio Arzilli (ORCID: https://orcid.org/0000-0002-5293-7300)
- Richard A. Brooker (ORCID: https://orcid.org/0000-0003-4931-9912)
- Roy A. Wogelius (ORCID: https://orcid.org/0000-0002-5781-2152)
- Sebastian Marussi (ORCID: https://orcid.org/0000-0003-4537-210X)
- Margherita Polacci (ORCID: https://orcid.org/0000-0003-3318-8700)
- Mike Burton (ORCID: https://orcid.org/0000-0003-3779-4812)
- Giuseppe La Spina (ORCID: https://orcid.org/0000-0001-6736-7884)
- Peter Lee (ORCID: https://orcid.org/0000-0002-3898-8881)
Institutions
- Institut polytechnique de Grenoble (FR)
- Università di Camerino (IT)
- Rutherford Appleton Laboratory (GB)
- Centre National de la Recherche Scientifique (FR)
- Diamond Light Source (GB)
- University of Manchester (GB)
- Istituto Nazionale di Geofisica e Vulcanologia (IT)
- University of Bristol (GB)
- Research Complex at Harwell (GB)
- Institut Néel (FR)
- University College London (GB)
- Université Grenoble Alpes (FR)
Publication Details
- Journal
- Science Advances
- Published
- 2024-08-16
- DOI
- https://doi.org/10.1126/sciadv.ado2585
- Citations
- 10
- Primary Topic
- Geological and Geochemical Analysis
- Type
- article
- Field-Weighted Citation Impact
- 5.34
Funders
- Sight Research UK
- Natural Environment Research Council