High-resolution bathymetry using Alvin scanning sonar at the Southern East Pacific Rise and its implication to the formation of collapsed lava lakes
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2007
Received: 8 September 2005
Accepted: 16 December 2006
Published: 7 May 2007
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.