From: "Scott, Brad"
Date: Wed, 12 Jul 1995 10:17:58 +1200 Subject: New volcanic eruption Tongan update (4 JULY); On friday June 23 the Tongan govt. asked the New Zealand govt. for advise on the eruption at Metis Shoal. I was able to fly up on a RNZAF maritime patrol flight on Sunday June 25 for a good look. I was also able to get a ride on a tug boat up to the island on 27-28 June but 2m seas prevented access. Below is a brief summary of the eruption to date. Activity was first observed on June 6, and the growth of the lava dome above sealevel was first observed on 14 June. By 20 June the lava dome was 240x280m and about 54m above sea level. Volcanic eruptions were also reported from 2 other locations. As part of the over flight we flew the 2 other reported eruption sites and can confirm there is only one eruption source. They are evidently the location of the aeroplanes which observed activity!. Volcanic activity is reported from Metis in 1851, 52, 1858, 1878, 1886, 1894, 1967 and 1979. On at least 5 occasions it appears that islands were formed. The 1967 and 1979 events erupted dacitic pumice and formed low angle tuff cones, which were soon eroded away. The 1995 lava type is not known at this time. Metis volcano rises about 1500m from the sea floor. We have no detailed bathymetry of the cone. The present eruption has formed a steep sided lava dome which has split and subsided between June 20 and 25 as the NE part flows down some form of topographic slope. On June 20-21 a small lobe was been extruded onto the top of the dome. By June 25 this lobe had been displaced NE about 40-50m and was lower than the highest point which is now on the south side. The NE front of the dome was actively growing on June 20-21 but had stopped by June 25. The Tongan govt. has been advised to place a no go zone around the island. They have also been breifed about LAZE (acid rain/fume), explosive outbursts, dome collapse and the formation of further shoals. Locally these volcanoes are known as 'Fonwafo'ow', which translates as Jack in a box! Brad Scott Volcano Surveillance Institute of Geological & Nuclear Sciences New Zealand