Report on Kavachi (Solomon Islands) — March 1981
Scientific Event Alert Network Bulletin, vol. 6, no. 3 (March 1981)
Managing Editor: Lindsay McClelland.
Kavachi (Solomon Islands) Submarine activity continues
Please cite this report as:
Global Volcanism Program, 1981. Report on Kavachi (Solomon Islands). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 6:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198103-255060.
8.991°S, 157.979°E; summit elev. -20 m
All times are local (unless otherwise noted)
Solair Captain Peter Cox overflew Kavachi on 9 January at 1540. At 30- to 60- minute intervals steam fountains rose to a height he estimated at 150 m. The sea was stained light brown for as much as 15-20 km from the volcano, but Cox saw no floating pumice.
Ministry of Natural Resources geologist A. Smith observed minor eruptive activity on 25 February. Submarine explosions apparently originating at 5-10 m depth transmitted shock waves to the surface. Some gas bubbles could be seen but no ejecta were evident. The prevailing wind drove seas to the NE, carrying an expanding plume of yellow-brown to yellow-green water visible on the surface for at least 2 km from the volcano.
Geologic Background. Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is one of the most active submarine volcanoes in the SW Pacific, located in the Solomon Islands south of Vangunu Island about 30 km N of the site of subduction of the Indo-Australian plate beneath the Pacific plate. Sometimes referred to as Rejo te Kvachi ("Kavachi's Oven"), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.
Information Contacts: D. Tuni, Ministry of Natural Resources, Honiara.