RUAPEHU ERUPTS

Waimarino Bulletin, Volume 6, Issue 267, 13 December 1988, Page 1

RUAPEHU ERUPTS

A hydrothermal eruption of Ruapehu occured last Thursday, at 10.10am. The eruption measured "quite strongly" on the Whakapapa seismograph, according to a Department of Conservation officer. Two earthquakes preceeded the eruption, one at 8.48am measuring 3.0 on the Richter Scale at one at 9.03am measuring 2.6. A hydrothermal eruption is an upwelling of hot water from the lake bottom, which upon Teaching the surface is emitted as clouds of steam. DoC staff at Whakapapa observed two clouds during the eruption, one appearing from the centre of the lake and one from the western part of the lake. One was a blue coloured cloud of sulphur dioxide gas. The eruption lasted about one minute and 40 seconds. DSIR scientist Peter Ottway from Wairake, who regularly monitors the crater, was at Mt Ruapehu after the eruption to measure the crater rim for distortion. Prior to the eruption the lake had been a blue colour and nine degreed celsius, which is the coolest the lake water had been since measurements began in the 1970's. The blue colour indicates no volcanic activity at the lake bottom. Since the eruption the lake water has turned grey.