Earthquake Commission IQ

Hydrothermal Activity

Introduction

Hydrothermal activity is the expulsion or action of hot, water-rich fluids returning to the surface after having been heated by hot rock or magma at depth. Ground water seeping down into the crust is heated and rises back to the surface through fissures and cracks, where it sometimes exits under pressure as super-heated water or steam. The most common examples are geysers, fumaroles (vents from which volcanic gas escapes) and hot springs.

Most of New Zealand’s hydrothermal activity occurs in the Taupo Volcanic Zone, a 250km long area that extends from Mt. Ruapehu to White Island.

Pohutu Geyser at Whakarewarewa in Rotorua (Institute of Geological and Nuclear Sciences)

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