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Metis Shoal Volcano | John Seach
Tonga
19.18 S, 174. 87 W
summit elevation 43 m
submarine volcano
Metis Shoal is located between Kao and Late islands.
During the 1995 eruption a 43 m high island formed, composed of a solid lava dome above the surface.
In December 2006 a flyover revealed an island still present at Metis Shoal. The island is temporary and sometimes erodes due to wave action. Areas of discolored water were present next to the island, the result of either erosion or fumarolic activity.
2019 Activity
Pilot observed white plume up to 17,000 ft altitude on 15 October 2019. No ash emission.
1995 Eruption
An eruption of Metis Shoal was observed on 6th June 1995. An island rose above the surface on 12th June. The eruptions produced a lava dome which grew to a diameter of 200-500 m and a height of 50-80 m.
1979 Eruption
In May 1979, floating pumice was seen in Tongan waters, on uncertain origin. On 19th June, the location was identified as Metis Shoal. In mid July, an island was observed 300 m long, 120 m wide, and 15 m high. In July 1979, pumice had reached N and E shores of Santa Isabel Island, in the Solomon Islands.
1967-68 Eruption
An eruption was observed at Metis Shoal volcano on 12th December 1967. In January 1968 eruption sent lava to a height of 300 m, and a island formed half a mile wide and 100 feet high. Reports from nearby ships described the eruption as intense and violent.
Captain Peter Bennett from the ship Tofua reported on the eruption of Metis Shoal volcano on 12th December:
"At the closest approach of 9 miles the volcanic eruption had the appearance of an incandescent island about half a mile long and 150 feet high, glowing cherry red at constant intensity. Above this island a dense pillar of steam and smoke ascended to 3000 feet and at approximately 1 minute intervals molten lava or boulders in parabolic arcs were observed being ejected to a height of 1000 feet."
Observations from a New Zealand airforce plane on 14th December recorded eruptions at Metis Shoal volcano:
"At the site of the eruption an island had formed and it was variously estimated to be 20 to 40 feet high and as much as 150 to 300 yards long. At the eastern (upwind) extremity of the island was a crater guessed to be 10 to 20 yards across. Its shape was circular with dark grey lips. Inside, the grey soon changed to a dark cherry red becoming brighter and more orange with increasing depth. These details were observed only momentarily when for a few seconds the smoke cleared about the crater..."
On 19th December Captain C. H. Hill-Willis of the vessel Aonui observed the island at Metis Shoal from a distance of 4 miles:
"the island was one third of a mile long and approximately 80 feet high. It was erupting from a single cone at intervals of roughly 3 minutes, with steam vapour rising to some 8,000 feet."
Chronology of events, Metis Shoal, Tonga (1967-68 eruption)
1. Submarine eruption begins at an unknown date.
2. Island emerges, subaerial eruptions—probably not earlier than 10 December 1967
3. First observation and report of subareal eruption 12 December 1967
4. Activity reached peak 31 December 1967 and ended by 7-8 January 1968
5. Maximum length, 700 m; width, 100 m; height, 15 m (±50%) 7 January 1968
6. Erosion of island down to "rocky outcrops" 25 January 1968
7. Island only "jagged rocks and water washing across" 1 February 1968
8. Island submerged, very high breakers on subsurface rock: 19 February 1968
9. Shoal completely beneath water with no breakers 1 April 1968
Further reading
Bryan, W.B., Stice, G.D. and Ewart, A., 1972. Geology, petrography, and geochemistry of the volcanic islands of Tonga. Journal of geophysical research, 77(8), pp.1566-1585.
Melson, W.G., Jarosewich, E. and Lundquist, C.A., 1970. Volcanic eruption at Metis Shoal, Tonga, 1967-1968: description and petrology. Smithsonian Contributions to the Earth Sciences.
Metis Shoal Volcano Eruptions
1995, 1979, 1967-68, 1894, 1886, 1878, 1858, 1852, 1851.