The Craters of the Moon thermal area in Wairākei is a typical acid sulfate geothermal system, with abundant fumaroles, steaming ground, mud pools, explosion craters and colourful soils.
Activity here hotted up as a consequence of the development of the Wairākei field for electricity generation, in 1958. As hot water was withdrawn from deep within the field, the water level in the deep reservoir dropped and the remaining water boiled more violently, producing more steam. Large quantities of this extra steam were able to escape at Craters of the Moon. The total heat output increased dramatically from a pre-development value of 40 megawatts to a high of 420 megawatts in 1964. It has since stabilised at about 200 megawatts.
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Photograph by Lloyd Homer
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