Additional Report for Kermadec Pumice

Floating Pumice (Kermadec Islands)

W of the Kermadec Islands, S Pacific Ocean


Index of Monthly Reports

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04/1983 (SEAN 08:04) Bubbling and floating pumice

08/1983 (SEAN 08:08) Pumice in the Tuamoto Archipelago; source unknown


Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

All times are local (= UTC + 12 hours)

04/1983 (SEAN 08:04) Bubbling and floating pumice

While sailing on his yacht Cookoos' Nest, Captain J. McInnis passed through the edge of a roughly 1-hectare area of small pieces of pumice on 6 April at 1206. He reported some "bubbling" but noted no smells. His location at the time of the sighting was fixed by satellite at 27.58°S, 177.40°E, several hundred kilometers W of the Kermadec volcanic trend. Previous pumice rafts in the area have drifted generally toward the W. Water depths in the area of the sighting are in excess of 4,000 m. Seismic records in New Zealand (roughly 1,400 km from the site) showed no earthquakes associated with the activity, and nothing was reported by the observer on Raoul Island (in the Kermadecs and about 460 km from the site).

Information Contacts: I. Everingham, Mineral Resources Dept., Fiji; W. Smith, DSIR, Wellington.

08/1983 (SEAN 08:08) Pumice in the Tuamoto Archipelago; source unknown

The source of the pumice remains unknown. Analysis of March and April records from the Réseau Sismique Polynésien (RSP) revealed no acoustic waves (T-phase) from eruptions other than that of Macdonald Seamount. However, the numerous small islands in the area of the Kermadecs, Tonga, Samoa, and Fiji interfere with acoustic waves, preventing effective T-phase monitoring of volcanic activity in some parts of the South Pacific. J. Talandier notes that measurements of surface currents in French Polynesia and similar latitudes suggest that pumice from Macdonald should drift eastward, away from the 6 April site.

Pumice came ashore at both the SE and NW ends of the Tuamoto Archipelago, on the Gambier Islands (23.15°S, 134.97°W) and at Rangiroa (15.00°S, 147.67°W), 4,800 km E and 3,900 km ESE of the 6 April observation. No information on the amount of pumice or the date of its arrival at these locations was available. Talandier noted that Rangiroa is very remote from known active volcanoes other than those in the Mehetia region, where eruptions occur at depths that are too great for production of pumice.

Information Contact: J. Talandier, Lab. de Géophysique, Tahiti.