New Zealand volcano shows unusual unrest
03 Jul 2008
Heavy snowfalls over New Zealand's North Island ski resorts at the heart of the Central Plateau might have brought chilly temperatures and delighted skiers but scientists are more interested in a hotspot that remains in the Mt Ruapehu crater lake.
Temperatures and gas in the crater lake are still high nine months after the last eruption when debris spewed five thousand metres into the sky and triggered two lahars.
Scientists say it doesn’t necessarily mean an eruption is likely, but the current unrest is unusual. Crater lake temperatures and gas levels usually follow a predictable pattern of returning to normal after eruptions.
Emergency management agencies have met to brush up on Mt Ruapehu eruption response plans and have identified ways to improve communications. The Central Plateau Volcanic Advisory Group reassured the public that they were watching the situation on Ruapehu very closely.
Last ‘Blue-sky’ eruption
Mt Ruapehu which sits in the middle of the North Island is one of the world’s most active volcanoes and last year crowds flocked to the area to witness the aftermath of the eruption. As the North Island’s highest point the region is home to two of New Zealand's largest commercial skifields, Whakapapa and Turoa.
The eruption last October occurred without warning and generated a 2.8 magnitude volcanic quake. Pilots flying in the area reported an ash column of about 5000 metres. It was described as a 'blue-sky' eruption, coming without warning, and going from nothing to full-on in about a minute.
Mt Ruapehu's last major eruptions occurred in 1995 and 1996 and just last year the tephra dam, which had been holding back the crater lake burst, sending a lahar down the mountain.
New Zealand has a number of active volcanoes including Raoul Island (Kermadecs), Mt Taranaki and White Island.
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