The website GeoNet has reminded New Zealanders that while the snow has arrived and Mount Ruapehu is a magnet, skiers and walkers need to be reminded that it is one of the country’s most active volcanoes.
Though it was now almost 10 years since the last eruption from Mt Ruapehu’s Crater Lake, there was a need to monitor activity.
Small eruptions only affect the summit plateau around Crater Lake, however the larger ones can generate lahars down the slopes.
“These larger, lahar generating eruptions occur on average about once every seven years and can impact the ski fields. So, remembering Ruapehu is an active volcano, it is a good idea to check out the hazard information before heading to the ski fields,” GeoNet said.
There are hazard posters and video clips that can be checked.
The monitoring of Ruapehu volcano and its Crater Lake includes seismic, acoustic, GPS sensors around the volcano, gas flights and sampling of the Crater Lake. The temperature and water level of the lake are also monitored by data-logger.
The website said on Friday Crater Lake was now cool, with the lake temperature at 19 degrees.
Research on the eruptive history of Ruapehu through Crater Lake has shown that the probability of an eruption increases when the lake was significantly warmer or cooler than the median temperature range.
“Eruptions have been significantly more frequent when the lake was hot rather than cold. Despite the current lower lake temperature, the likelihood of an eruption remains low - in the 10 years since the last eruption the lake has cooled seven times to below 16°C and heated six times to over 38°C with no eruptions,” GeoNet said.
The GeoNet monitoring of the volcano and Crater Lake does however indicate the volcano is alive.