Journal Article

Constraints on a plume in the mid-mantle beneath the Iceland region from seismic array data

M. J. Pritchard, G. R. Foulger, B. R. Julian and J. Fyen

in Geophysical Journal International

Volume 143, issue 1, pages 119-128
Published in print October 2000 | ISSN: 0956-540X
Published online October 2000 | e-ISSN: 1365-246X | DOI:
Constraints on a plume in the mid-mantle beneath the Iceland region from seismic array data

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Teleseismic P waves passing through low-wave-speed bodies in the mantle are refracted, causing anomalies in their propagation directions that can be measured by seismometer arrays. Waves from earthquakes in the eastern Pacific and western North America arriving at the NORSAR array in Norway and at seismic stations in Scotland pass beneath the Iceland region at depths of ∼ 1000–2000 km. Waves arriving at NORSAR have anomalous arrival azimuths consistent with a low-wave-speed body at a depth of ∼ 1500 km beneath the Iceland–Faeroe ridge with a maximum diameter of ∼250 km and a maximum wave-speed contrast of ∼ 1.5 per cent. This agrees well with whole-mantle tomography results, which image a low-wave-speed body at this location with a diameter of ∼ 500 km and a wave-speed anomaly of ∼ 0.5 per cent, bearing in mind that whole-mantle tomography, because of its limited resolution, broadens and weakens small anomalies. The observations cannot resolve the location of the body, and the anomaly could be caused in whole or in part by larger bodies farther away, for example by a body imaged beneath Greenland by whole-mantle tomography.

Keywords: array; Iceland; mantle; plume; seismology

Journal Article.  4956 words.  Illustrated.

Subjects: Geophysics

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