New Zealand - Eruption threat real, warns expert

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Eruption threat real, warns expert
SUSAN PEPPERELL - Sunday Star Times
Last updated 05:00 07/11/2010

Ash plume: Mt Ruapehu erupts.
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While Cantabrians may have upskilled themselves on surviving earthquakes since September's 7.1 shake, North Islanders are being told to bone up on volcanoes.

An eruption is coming, warns GNS Science volcanologist Dr Graham Leonard, and anyone living pretty much north of Wellington should be prepared.

Leonard is part of a group of volcano experts advising local bodies, emergency services, government agencies and district health boards at a conference in Taupo this week, on how they can best prepare to cope with the aftermath of an eruption.

The venue is deliberately fitting – the Taupo volcanic zone is the most productive volcanic system on Earth. Eruptions, when they happen, are big.

Participants will be told it's not the lava or the possibility of lahar that Kiwis need worry about, but ash. "Lava flows and lahars are very damaging, but they tend to be local. We spend a lot of time talking about volcanic ash because worldwide it's the most disruptive and travels a long way."

Fortunately, New Zealand volcanologists are world leaders when it comes to understanding the impact of ash fallout and know how it affects water and electricity supply, waste water treatment plants, pasture and buildings.

Expertise developed following the 1996 eruption of Mt Ruapehu, and this year Kiwi scientists were called in to advise on the likely impact of ash fallout following the eruption of Iceland's Mt Eyjafjallajokull, which closed airports across Europe.

Also on the agenda of the Taupo conference is an insight into supervolcanoes, capable of pushing out 500 cubic kilometres of magma or more.

"It's a number you can't fathom," says Leonard, who warns that there have been at least two in the world in the past 350,000 years.

New Zealand doesn't harbour any supervolcanoes but it does have its younger sibling, the caldera volcano. Taupo, Okataina and Rotorua are considered the most active though Leonard says the Taupo volcanic area has seven or eight calderas that have been active in the last million years.