Friday, March 23, 2007
Mt Ruapehu's eruption traps NZ farmers on their land
As farmers around the mountain began a clean-up, many were counting their blessings after little damage occurred when more than a million litres of debris inside the volcanic crater burst from the banks between 11am and 12 noon on Sunday (1000-1100 AEDT).
The stream of debris, known as a lahar, had been predicted for more than a decade, amid fears it could destroy bridges and harm people in the area.
A $NZ10 million warning system was in place to alert farmers that it was imminent.
Carla Doolan who owns a beef and sheep farm with her husband was still trapped on her property, after roads were covered over with mud and silt.
"We can't get out of our property. The bridge is still standing thankfully but that is still subject to an engineer's report before we can cross it. The access way on the approach to the bridge has completely washed out," Doolan said.
"It actually came down in stages ... Initially it was just a lot of logs and debris that came down first and then the river level gradually built up and it was more like silty mud flow type material," she said.
"It could definitely have been much worse."
"We have already had diggers in today and they have started the clean-up. They are just trying to establish access. It is still not passable and you definitely can't get there by vehicle, but we have had people fly in," she said.
Sue Blackburn, who lives locally, said she was grateful there was not more damage when the lahar flowed down a river on her property.
"It went right over a bridge that goes onto my son's place. It actually went over," she said.
"We had plenty of warning. All of the warning systems worked well," Blackburn said.
Dave Wakelin from New Zealand's Department of Conservation said the lahar caused little inconvenience.
"It passed down the river safely. We had a round-the-mountain walking bridge that was severely damaged. Apart from that, everything went according to plan," said Wakelin said.
"The response plan worked and if anything it was probably a minor inconvenience to the public rather than anything else," he said.
He said rocks as big as cars smashed together in the lahar, but there was little damage to people or structures in the remote area.
"There are obviously some people who live on farms further down, but not right on the banks of the river," Wakelin said.
The lahar was the 46th on Mount Ruapehu since 1953 when a giant lahar formed on Christmas eve, washing away a rail bridge as a train approached, killing 151 people.
"It is just the nature of a volcano. It is a natural event. This was a moderate lahar, because of the way it released. It released over almost an hour. It wasn't a big full-volume release of water," Wakelin said.
The muddy debris in Mt Ruapehu formed after eruptions in 1995 and 1996 caused volcanic material to block off an outlet for a lake in the crater, causing a dam to form.
"It always will be a danger. That is an active volcano. The most common lahars are eruption lahars, where the volcano, which is underneath the lake actually throws the water out of the lake and it can flow down the sides of the mountain or down the river itself," Wakelin said.