Message #8149

[Adam Hawthorne]

GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L13609, doi:10.1029/2005GL023205, 2005

Evidence of explosive seafloor volcanic activity from the Walvis Ridge, South Atlantic Ocean

J. H. Haxel

Cooperative Institute for Marine Resources Studies and NOAA Pacific Marine Environmental Laboratory, Oregon State University, Newport, Oregon, USA




R. P. Dziak

Cooperative Institute for Marine Resources Studies and NOAA Pacific Marine Environmental Laboratory, Oregon State University, Newport, Oregon, USA




Abstract
Hydrophones moored in the North Atlantic Ocean recorded a sequence of explosive, volcano-acoustic signals originated at the Walvis Ridge in the South Atlantic Ocean. 365 explosive signals were detected from the Walvis Ridge beginning 24 November 2001 continuing through March 2002. The largest swarm began on 19 December at 2329 GMT, and lasted 1.25 hrs producing 32 locatable events. Swarm locations are centered on the northern flank of an unnamed seamount (−32.96°S; −5.22°W), northwest of Wüst Seamount. These signals are interpreted as volcanogenic explosions due to similarities with acoustic signals recorded from a confirmed submarine eruption in the Caribbean in 2001 (Kick'em Jenny volcano). The observations presented suggest recent magmatic activity along the Walvis Ridge may be unrelated to the Tristan da Cunha mantle plume. Furthermore, these events lend support for an extensional fracture-zone model resulting in the recurrence of volcanic activity along older segments of large-scale sea floor lineaments.

Received 11 April 2005; accepted 10 June 2005; published 15 July 2005.

Index Terms: 3045 Marine Geology and Geophysics: Seafloor morphology, geology, and geophysics; 3075 Marine Geology and Geophysics: Submarine tectonics and volcanism; 3035 Marine Geology and Geophysics: Midocean ridge processes.


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