Tarawera eruption warning

By JO-MARIE BROWN

Bay of Plenty civil defence chiefs have been urged to devise new plans following the release of new research into devastation another eruption from Mt Tarawera would have on the region.

A thesis written by University of Canterbury geology student Scott Barnard says an eruption from Tarawera, as occurred in 1886 when the Pink and White Terraces were destroyed, would wipe out some settlements and cause problems as far away as Whakatane and Tauranga.

Waves of superheated gas and ash would flatten homes around Lake Rotomahana, Rerewhakaaitu and Waimangu, and forest fires started by lava flows could quickly spread, Mr Barnard concluded.

Small rocks up to 3.2cm in diameter would rain down over a 20km radius; larger ones that could break windows or even kill people and animals would fall up to 12km away, while 12.8cm "bombs" may be thrown up to 6km from the volcano's vent.

Nearby in Rotorua, up to 30cm of ash could fall depending on the prevailing winds, causing roofs to collapse, roads and the airport to close, and large numbers of residents loca ls to evacuate.

Hazardous eruptions could also occur in the city's geothermally active areas and bursts of hydrogen sulphide and carbon dioxide could asphyxiate people standing nearby.

The thesis, tabled at an Environment Bay of Plenty meeting late last week, says light ash was likely to fall in Tauranga, disrupting the city's electricity supply.

Whakatane's roads and water supply would be affected.

Environment BOP's regional civil defence officer Russ Martin said the thesis was an extremely useful reminder of a disaster which the district would have to deal with at some stage in the future.

"If you talk to scientists they will tell you that anywhere from Ruapehu through to White Island an eruption could occur," Mr Martin said.

"There's absolutely nothing to say that any part of that area is completely secure."

The region's Civil Defence Emergency Management Group, which comprises the mayors of all six local councils and Environment BOP's chairman, will be asked to discuss the thesis and the steps it recommends to mitigate possible effects.

Suggestions Mr Barnard has made include not building any more homes near Mt Tarawera, moving earthmoving and road maintenance equipment away from Rotorua to protect it from ash, and stockpiling electricity cables to quickly replace downed transmission lines.

Environment BOP has also requested the civil defence group look at whether monitoring systems for the area are sufficient.

Institute of Geological and Nuclear Sciences volcano geophysicist Craig Miller says seismic activity around the Okataina volcanic area, which includes Mt Tarawera, was being monitored 24 hours a day.

"If there's going to be a big eruption, there's normally a lot of earthquake activity prior to that," he said.

Tarawera had erupted twice in the past 700 years and it was still considered an active volcano, but it was impossible to tell when the next eruption would occur.

Contingency plans

* Ban on building near Mt Tarawera recommended.

* Earthmoving and road maintenance equipment moved away from Rotorua to protect it from ash.

* Electricity cables stockpiled to quickly replace downed transmission lines.