Unexpected large eruptions from buoyant magma bodies within viscoelastic crust

2020

Article référencé dans le Web of Science WOS:000536569900001

Sigmundsson F., Pinel Virginie, Grapenthin R., Hooper A., Halldorsson S. A., Einarsson P., Ofeigsson B. G., Heimisson E. R., Jonsdottir K., Gudmundsson M. T., Vogfjord K., Parks M., Li S. Q., Drouin V., Geirsson H., Dumont S., Fridriksdottir H. M., Gudmundsson G. B., Wright T. J., Yamasaki T.

Nature Communications, 2020, 11 (1), p. art. 2403 [11 p.] ISSN 2041-1723

Large volume effusive eruptions with relatively minor observed precursory signals are at odds with widely used models to interpret volcano deformation. Here we propose a new modelling framework that resolves this discrepancy by accounting for magma buoyancy, viscoelastic crustal properties, and sustained magma channels. At low magma accumulation rates, the stability of deep magma bodies is governed by the magma-host rock density contrast and the magma body thickness. During eruptions, inelastic processes including magma mush erosion and thermal effects, can form a sustained channel that supports magma flow, driven by the pressure difference between the magma body and surface vents. At failure onset, it may be difficult to forecast the final eruption volume; pressure in a magma body may drop well below the lithostatic load, create under-pressure and initiate a caldera collapse, despite only modest precursors. Large-volume volcanic eruptions can occur despite only limited precursory activity. Here the authors show that modelling the combined effects of buoyant magma, viscoelastic earth behaviour, and sustained magma channels can explain such behaviour of volcanoes and gives an estimate of pressure evolution in magma bodies.

Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Géophysique interne [066]

ISLANDE ; BARDARBUNGA VOLCAN

Fonds IRD [F B010078123]

fdi:010078123