Volcanic activity on Ruapehu increases

Ruapehu Bulletin, 11 July 1995, Page 1

Volcanic activity on Ruapehu increases

The Department of Conservation has issued a public warning for people to stay away from the Crater Lake area on Mt Ruapehu following an increase in volcanic activity on the mountain. Two eruptions from the Crater Lake have occurred in the last seven days, accompanied by volcanic earthquakes recorded on seismic equipment at Mt Ruapehu. Continued frequent hydrothermal activity has also been observed. The first eruption last Thursday deposited lake water and debris on the surrounding shore, including on the Institute of Geological and Nuclear Science (IGNS) Argos monitoring equipment. A second eruption, recorded on Monday last week threw lake water and sediment into the air and resulted in a small lahar (mudflow) about 30 to 50 metres wide from the lake' s

outlet down the Whangaehu River. The lahar was not large enough to be recorded by equipment at Tangiwai. Residents of the nearby National Park and Ohakune

towns have reported feeling several earth tremors. However these tectonic earthquakes (as opposed to volcanic earthquakes) are Turn to Page 2

Volcanic activity on Ruapehu increases

FROMPAGEl thought to be unconnected to the increase in volcanic activity. DoC has warned the public to stay away from the Crater Lake and Basin areas until further notice. The heightened state of activity means the area is considered to be dangerous. DoC spokesperson, Lianne Fraser said that although

hydrothermal activity has been happening regularly over a period of months, the recent eruptive activity is unpredictable and people should not go any closer than the Dome Shelter or high ridges around the lake. The areas on Mt Ruapehu most at risk from a major lahar are the Whakapapa Skifield and Whakapapa Village. Both DoC and the

skifield operator have safety plans in place to handle a lahar situation and staff are trained to react quickly to any change in alert status. Lianne Fraser said that visitors to Mt Ruapehu should make sure they follow instructions from skifield and DoC staff should a lahar warning occur. Scientists from IGNS will continue to monitor the situation using scientific recording equipment and DoC staff are carrying out visual checks as weather conditions permit. It is 50 years since the last major eruption of Mt Ruapehu although moderate lahars occurred in 1969 and 1975. To mark the-5Qth anni versary various activities, including a Civil Defence/DoC Lahar Exercise has been planned. DoC staff have commented that the mountain seems to be making its own anni versary event.