Ash from Taupo eruption found across Pacific

Press, 24 July 1986, Page 37

Ash from Taupo eruption found across Pacific

PA Wellington Volcanic ash from the southern hemisphere’s largest-known eruption, which occurred in the Taupo area about a quarter of a million years ago, has been found in sea floor sediments across much of the Pacific ocean.

The eruption from an ancient volcano in the Taupo-Wairakei area is now thought to be about 40 times as big as the famous Krakatoa eruption last century which blew apart an Indonesian island.

The earth’s climate cooled immediately after the eruption, leading to speculation that the gigantic amounts of ash thrown into the atmosphere by the eruption may have caused a “volcanic winter”.

Dr Lionel Carter, a marine geologist from the D.S.I.R.’s Division of Marine and Freshwater Science said that ash from what is known as the Mount Curl eruption

might have landed as far away as the sea off South America. It covered the area of about 30 million square kilometres to a depth of 2cm. A paper on the underocean find was published in the leading British science journal, “Nature.” earlier this year. It was a joint project from scientists from the universities of Victoria, Waikato and California and the D.S.I.R.

The study was based on core samples of ocean mud taken by Dr Cam Nelson, of Waikato University, on the United States drilling ship Glomar Challenger in 1984 and from similar samples undertaken by the former New Zealand oceanographic research ship Tangaroa off New Zealand.

Dr Paul Froggatt, of Victoria University, used an electron microprobe to compare tiny fragments of volcanic glass in the ash layers with other ash deposits already studied in New Zealand.

The Mount Curl eruption is thought by recent work by New Zealand volcanologists to have thrown out perhaps 1000 cubic kilometres of magma, including at least 700 cubic kilometres of ash.

By comparison the 1980 eruption of Mount St Helens in the United States erupted only about one cubic kilometre of material.

The Taupo area is known for its huge but infrequent eruptions. The most recent, about 1800 years ago, was one of the biggest at 100 cubic kilometres, but still a 10th the size of Mount Curl.

Dr Jim Cole, reader in geology at Victoria University, said the world’s largest known volcanic eruption was in the Yellowstone Park area of the United States about 6000 years ago. This erupted about 2400 cubic kilometres of material, more than double the size of the. Mount Curl eruption.