Magma degassing and intermittent lava dome growth | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Magma degassing and intermittent lava dome growth

Type de publication:

Journal Article

Source:

Geophysical Research Letters, Volume 35, Ticket 20 (2008)

ISBN:

0094-8276

Numéro d'accès:

WOS:000260596700004

Mots-clés:

Dynamique des Fluides Géologiques ; N° de contribution : 2431, UMR 7154

Résumé:

<p>After its 1980 explosive eruption, Mount St Helens developed a lava dome that grew intermittently for several years. Each growth episode was followed by a long repose, suggesting that the magma column above the reservoir was in hydrostatic equilibrium. A mechanism allowing an increasingly thicker dome is proposed. Loading of the crater floor by the dome acts to prevent gas leakage from magma by closing fractures around the volcanic conduit. Fractures get closed down to a depth that increases as the dome grows. Calculations of dome thickness as a function of dome radius are in good agreement with observations. Renewed growth is triggered by the spreading of the dome. Gas retention over a larger depth extent allows smaller magma densities and a taller magma column above the reservoir. According to this model, small domes can in fact promote explosive volcanic conditions and be unstable. Citation: Taisne, B., and C. Jaupart (2008), Magma degassing and intermittent lava dome growth, Geophys. Res. Lett., 35, L20310, doi: 10.1029/2008GL035432.</p>