Hidrológiai Közlöny 1995 (75. évfolyam)

4. szám - Scheuer Gyula–Szentirmai Lászlóné–Szentirmai László: Új-Zéland gejzírjei és legismertebb hévizes területei

251 The geysers ind the mala thermái water resources In New Zealand Scheuer, Gy, Ms and Mr Szentlrmal, L. Abstract: The northera island of New Zealand is a highly active member of the seismic beit surrounding the Pacific Basio. Several volcanoes (Tongario, Ruapehu, etc.) axe still active on the island. Recent volcanism is associated with the NRE-SW oriented tectonic lines traversing the central part of the island. The origins of volcanic activity have been traced back to the Mesosoic Age. One of the largest eruption in recent times occurred in 1886 (Tarawa). Mostly pyroclastic debris (volcanic tuff) was created during the eruptions, lava spills having been of inferior importance. The most common volcanic rocks in the island is rhyolite and the tuffs thereof. Neogenic volcanism was accompained by vigorous hydrothermal activity. The hydrotherms in the area between the Totorua and Taupo lakes are most important and best known, where gases, steam and hot water emerge to the surface from volcanic rocks at five sites. The geysers are the most spectacular forms in which these appear. Thermal springs are know to exist in a number of places. As regards hydrochemistry, the upwelling hot waters belong to the sodium chloride group with a high (150 - 700 mg/L) silicate contept. Somé of these were found to be enriched in rarer substances, such as arsenic, anthimony, sulphur, manganese, etc.). The geothermal resources have been developed at two of the sites. The first, the Wairakei power station was commissioned as eariy as 1958 to generate electric power from the steam rising to the surface with the springs originating between 600 and 1200 m depths. Geothermal power stations provide presently 8 % of the power demand in the country. From the surveys performed the geothermal resources available for development have been estimated at 2660 MW, of which 300 MW have already been developed. Keywords: Thermal water resources, geysers, hydrothermal eruptions, geothermal energy.