White Island (Whakaari) is New Zealand’s most continuously active and largest volcano by volume. It is an uninhabited island about 2 km in diameter and 48 km from the coast of the Bay of Plenty. It marks the northern end of the Taupo Volcanic Zone.
70% of the cone is under the sea, and the the highest point reaches 321 m altitude. Most of the island is occupied by the Main Crater, with the crater floor being less than 30 m above sea level.
White Island has been active for at least 150,000 years, It is a strato-volcano, (composite cone volcano) made of layers of andesite lava flows and pyroclastic deposits (tephra). Since human settlement in New Zealand there has been continual low level activity and small eruptions. From 1976 until 1993 there were frequent small eruptions making this the island’s most active period in hundreds of years. Ash and gas plumes rose as high as 10 km when lava bombs and blocks were thrown into the sea and occasionally the glow of red hot rock was visible at night from the Bay of Plenty coast.
Sulphur mining occurred at intervals from the 1880’s until the 1930’s and the remains of a factory can be seen on the island. Eleven miners were killed by a debris avalanche in 1914, when part of the crater rim collapsed.
Gases dissolved in the magma escape and rise towards the surface where they mix with, and heat the groundwater beneath the crater floor. This produces fumaroles, and the white steam/gas cloud which is usually present above White Island. This acidic cloud can sting the eyes and skin, affect breathing and damage equipment and clothes. Source: GNZ Science.
I was an invited scientist to assist with with the repair of the telimetry equipment that was on the island which had been damaged by a major eruption in 1976. We headed out to the Island on the Saturday, after the significant eruption
had occurred on the previous Thursday, which took the island's seismic monitor
and transmitter off-line.
The following images are of my return trip in November 2010 and with some of them I compare the same scenes as in 1976 with those in 2010.
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