'Quake swarm felt locally

Waimarino Bulletin, Volume 4, Issue 23, 4 November 1986, Page 2

'Quake swarm felt locally

Several tremors have been felt in the Ohakune region over the last two weeks. The first was felt as a single sharp jolt preceded by a loud rumbling noise in the early hours of Thursday morning 23 October. !t happened at 0549. The second occurred the next day on Friday evening, 24 October. at about 7.30pm. The third was on Sunday, 26 October, at 12.54pm. It was felt as a swaying motion accompanied by a rumble lasting 2-3 seconds. On Mopday evening. (Labour Day), another quake was felt at 5.26pm. The Bulletin contacted the Seismological Observatory in Wellington to seek an explanation for this series of earthquakes. They said they had recorded only two of them - the one on Labour Day which measured 5.8 on the Richter Scale and was centred at a depth of 100km below Taupo and the one on Friday evening which measured 4.0 on the Richter Scale but its location was still to be determined.

They were interested to hear about the other two which they said must have been a local rather than a regional phenomenon because they were not recorded on the Wellington seismograph. They explained that theirequipment in Wellington only detects tremors measuring above 3.0 on the Richter Scale. We then contacted Paul Dale. Chief Ranger at Whakapapa, who said that all these tremors had been recorded on their equipment. He also said that there had been a very slight increase in the temperature of the Crater Lake since the previous reading a month earlier. It measured 22.5°C. but this was not significant because the temperature varied between 10° and 45° and often increased after a spell of cold weather. "But what was interesting was when we took this temperature we noticed the lake level surging by about 200mm." "However no trendscould be read into the pattern of tremors or the behaviour of the lake at this stage and I'm not planning to pack my bags yet," he said.