No practice for volcanologists

Waimarino Bulletin, Volume 6, Issue 228, 26 January 1988, Page 9

No practice for volcanologists

A pattern of activity in Mt Ruapehu's Crater lake had DSIR investigating signs of possible pending eruption with more than usual interest last week. A Taupo based surveyor with the NZ Geological Survey, Mr Peter Otway, said lake temperature fluctuations and other signals started to show a pattern recOgnised from past experience as a precursor to eruption. But a check on the mountain's 'vital signs' last week revealed the pattern had bcen broken and the

situation was quite norma!'. A precise survey of the Crater lake is carried out by the DSIR monthly. Temperatures are recorded and the diameter of the crater measured for the constrictions or expansions that could indicated a build-up of pressure under the vent. Mr Otway said the recent changes were very minor. It was their particular pattern which indicated something might be up. Eruption is a term that denotes different things to different people. To the experts, bubbling or the geyser-like sprays from the

Crater Lake last AugustSeptember are termed 'eruptions'. To local residents the term often induces fears of something a great deal more violent. Scientists are confident of being able to predict certain classes of eruption, but the last few years at Mt Ruapehu had been relatively quiet. "There is a tremendous potential threat from Ruapehu with so many people on its slopes at a time. The lahar warning system would tell us if a large eruption was taking place so people could be moved from lower slopes." Contd on back page.

Volcanology practice

cont from P9. Those monitoring actiVity wanl to get to the stage of foreseeing the risk before it happens but the ironic fact is the lack of big eruptions recently "makes it hard to practice." Those involved are trying all sorts of different approaches but in a way the more they learn, the more they see how complex nature is, Mr Otway said.