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GEOPHYSICAL RESEARCH LETTERS,
VOL. 33,
L03312,
4 PP., 2006
doi:10.1029/2005GL024870
Unprecedented pressure increase in deep magma reservoir triggered by lava-dome collapse
College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
Department of Terrestrial Magnetism, Carnegie Institution Washington, Washington, D. C., USA
Department of Terrestrial Magnetism, Carnegie Institution Washington, Washington, D. C., USA
Department of Geosciences, University of Arkansas, Fayetteville, Arkansas, USA
Department of Earth Sciences, Bristol University, Bristol, UK
College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
Division of Earth and Ocean Sciences, Duke University, Durham, North Carolina, USA
Division of Earth and Ocean Sciences, Duke University, Durham, North Carolina, USA
College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
Montserrat Volcano Observatory, Flemings, Montserrat, BWI
Geosciences, Arizona State University, Tempe, Arizona, USA
Montserrat Volcano Observatory, Flemings, Montserrat, BWI
Department of Geosciences, University of Arkansas, Fayetteville, Arkansas, USA
Department of Terrestrial Magnetism, Carnegie Institution Washington, Washington, D. C., USA
School of Earth Sciences, Leeds University, Leeds, UK
Montserrat Volcano Observatory, Flemings, Montserrat, BWI
The collapse of the Soufrière Hills Volcano lava dome on Montserrat in July 2003 is the largest such event worldwide in the historical record. Here we report on borehole dilatometer data recording a remarkable and unprecedented rapid (∼600s) pressurisation of a magma chamber, triggered by this surface collapse. The chamber expansion is indicated by an expansive offset at the near dilatometer sites coupled with contraction at the far site. By analyzing the strain data and using added constraints from experimental petrology and long-term edifice deformation from GPS geodesy, we prefer a source centered at approximately 6 km depth below the crater for an oblate spheroid with overpressure increase of order 1 MPa and average radius ∼1 km. Pressurisation is attributed to growth of 1–3% of gas bubbles in supersaturated magma, triggered by the dynamics of surface unloading. Recent simulations demonstrate that pressure recovery from bubble growth can exceed initial pressure drop by nearly an order of magnitude.
Received 6 October 2005; accepted 5 January 2006; published 10 February 2006.
Citation: (2006), Unprecedented pressure increase in deep magma reservoir triggered by lava-dome collapse, Geophys. Res. Lett., 33, L03312, doi:10.1029/2005GL024870.
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