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Imaging the crustal magma sources beneath Mauna Loa and Kilauea volcanoes, Hawaii

Paul G. Okubo·Harley M. Benz·Bernard A. Chouet
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Abstract

Three-dimensional seismic P-wave traveltime tomography is used to image the magma sources beneath Mauna Loa and Kilauea volcanoes, Hawaii. High-velocity bodies (>6.4 km/s) in the upper 9 km of the crust beneath the summits and rift zones of the volcanoes correlate with zones of high magnetic intensities and are interpreted as solidified gabbro-ultramafic cumulates from which the surface volcanism is derived. The proximity of these high-velocity features to the rift zones is consistent with a ridge-spreading model of the volcanic flank. Southeast of the Hilina fault zone, along the south flank of Kilauea, low-velocity material (<6.0 km/s) is observed extending to depths of 9–11 km, indicating that the Hilina fault may extend possibly as deep as the basal decollement. Along the southeast flank of Mauna Loa, a similar low-velocity zone associated with the Kaoiki fault zone is observed extending to depths of 6–8 km. These two upper crustal low-velocity zones suggest common stages in the evolution of the Hawaiian shield volcanoes in which these fault systems are formed as a result of upper crustal deformation in response to magma injection within the volcanic edifice.

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Paul G. Okubo, Harley M. Benz, Bernard A. Chouet. 1997. Imaging the crustal magma sources beneath Mauna Loa and Kilauea volcanoes, Hawaii. https://doi.org/10.1130/0091-7613(1997)025%3C0867%3Aitcmsb%3E2.3.co%3B2

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