Magma storage beneath axial volcano on the Juan de Fuca mid-ocean ridge

Publication Type  Journal Article
Year of Publication  2001
Authors  West, M.; Menke, W.; Tolstoy, M.; Webb, S.; Sohn, R.
Journal Title  Nature
Volume  413
Issue  6858
Pages  833-836
Journal Date  Oct 25
ISBN Number  0028-0836
Accession Number  ISI:000171750200043
Key Words  east pacific rise; de-fuca; partial melt; sea-floor; ground deformation; seismic tomography; velocity structure; 1998 eruption; rocks; temperature
Abstract  

Axial volcano, which is located near the intersection of the Juan de Fuca ridge and the Cobb-Eickelberg seamount chain beneath the northeast Pacific Ocean, is a locus of volcanic activity thought to be associated with the Cobb hotspot(1). The volcano rises 700 metres above the ridge, has substantial rift zones extending about 50 kilometres to the north and south, and has erupted as recently as 1998 (ref. 2). Here we present seismological data that constrain the three-dimensional velocity structure beneath the volcano. We image a large low-velocity zone in the crust, consisting of a shallow magma chamber and a more diffuse reservoir in the lower crust, and estimate the total magma volume in the system to be between 5 and 21 km(3). This volume is two orders of magnitude larger than the amount of melt emplaced during the most recent eruption(3,4) (0.1-0.2 km(3)). We therefore infer that such volcanic events remove only a small portion of the reservoir that they tap, which must accordingly be long-lived compared to the eruption cycle. On the basis of magma flux estimates, we estimate the crustal residence time of melt in the volcanic system to be a few hundred to a few thousand years.

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485JATimes Cited:12Cited References Count:30

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