Craters of The Moon (geothermal Site) - History

History

In 1859 Ferdinand von Hochstetter, an Austrian geologist who traveled through the area, reported a colossal column of steam from the Karapiti Blowhole (fumarole), observable from about 20 km away. It was difficult to approach because steam vents and springs covered the valley floor and the ground was warm, soft, iron-stained clay for great distances around. By the beginning of the 20th century the Blowhole was a tourist attraction, albeit not of the level of the nearby Wairakei Geyser Valley. It's worthwhile reading the “Impression of a Trip” in 1927, in which the Karapiti Blowhole is named “the safety valve of the North Island”:

”After dinner (which was served at 6 p.m.) we took our seats in the car which went to Karapeeti (the safety valve of the North Island) and the “Huka” falls, a little higher up the Waikato.

Karapeeti blow hole is an escaping volume of superheated steam with a pressure of 180 lbs. to the square inch coming through an aperture two feet by one foot. The guide lit a sack sprinkled with kerosene so that the visitors could see the escaping steam in the darkness and after the sack had partly burnt away he picked it up on a stick and shook the burning pieces down into the blow hole. These were immediately carried up in the jet of steam and presented a very weird fireworks effect, the sparks remaining alight, proving that it was super-heated or dry steam. This blow hole, according to Maori tradition, has been constant for the last 200 years and the Maoris of the early days of New Zealand used this column of steam as a beacon to guide them with their canoes across Lake Taupo which is six miles distant.”

An information leaflet of New Zealand Railways of 1940 speaks about the “Inferno of Karapiti”. The phenomenon was usually viewed at night. A piece of smouldering sacking was applied to the blowhole. Then the “jet, filled with smoke and burning shreds becomes a whirling inverted cone flashing with thousands of yellow sparks in a brilliant pyrotechnic display”.

In 1950 the area was described as being mostly warm clay with small patches of hot ground and mudpools. “The Karapiti Blowhole was still impressive, though apparently much less intense than when Hochstetter saw it”.

A most important change in the region has been the building of the Wairakei Power Station (150 MW) in the 1950s, about 2 km. north of the field. This reduced the pressure in the hot water systems below the earth surface. Since then much of the geothermal activity in the region has dramatically changed, as did the geothermal activity at Craters of the Moon. The geysers at Wairakei Geyser Valley totally disappeared, but the heat output at Craters of the Moon increased. A lot of hydrothermal eruptions occurred, which formed the craters.

In 1950, the total heat output at Craters of the Moon was about 40 MW (megawatts). By 1958, it had increased to about 90 MW. In 1964 it was 420 MW. After 1964 the output declined to about 220 MW in 1979. The most recent estimate being about 200 MW in 2000.

Heat output from the Karapiti Blowhole followed a similar pattern. In the 1950 it was 12 MW. It increased to a maximum of about 38 MW during the mid 1960s. Then it dropped to about 7 MW in 1978. The blowhole finally ceased altogether in 1987.