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High-resolution bathymetry using Alvin scanning sonar at the Southern East Pacific Rise and its implication to the formation of collapsed lava lakes

Earth, Planets and Space200759:BF03353101

https://doi.org/10.1186/BF03353101

Received: 8 September 2005

Accepted: 16 December 2006

Published: 7 May 2007

Abstract

A high-resolution bathymetric map of a collapsed lava lake on the ridge crest of the superfast-spreading Southern East Pacific Rise was constructed. The data were acquired during the MOAI’98 Cruise using a pencil-beam scanning sonar that was installed on the submersible Alvin. The map covers an area of 200 × 350 m at the Oasis hydrothermal site (17°25.4′S, 113°12.3′W) where low-temperature fluids are venting from a collapsed lava lake. The collapsed lava lake is 250 m long, with a mean width of 10 m in parallel to the spreading axis on the western flank of the ridge crest. The estimated volume of lava that has drained out is about 7000 m3 erupted from a single event. This small amount of melt and frequent contacts between “young” and “younger” flows indicate that volcanism at the superfast-spreading ridge system is characterized by frequent eruptions of very small volumes of magma.

Key words

Collapsed lava lakescanning sonarEast Pacific Risehydrothermal activitysubmersible Alvinmid-ocean ridge