Lahar sends raging torrent of mud and debris down Whangaehu

A LAHAR surged down Mt Ruapehu yesterday sparking road closures and alarm, but causing no major damage or injuries.
The tephra dam on the mountain's crater lake burst about 11am creating a lahar, or mudflow, which carried debris down the mountain and into the Whangaehu River.
Witnesses said it "roared" down the river and was a spectacular sight with huge trees and boulders being swept against bridges.
Department of Conservation spokesman Dave Wakelin said the lahar was "moderate".
"The first indication that something was happening was some high sensor levels recorded from one of the geophones just after 10am," Mr Wakelin said.
The tephra dam was thought to have collapsed over a 45-minute period, releasing the lahar as a series of "pulses" and not a large explosive release.
Mr Wakelin said there were two lahars: a smaller one followed by a bigger flow about 15 minutes later. Witness Andy Jarden said big boulders "rumbled" against the piers of the Tangiwai Rail Bridge.
"They were smacking against them. There were big trees coming out of the water then completely disappearing," he said.
Mr Jarden said that initially the lahar wasn't what he expected.
"It wasn't the wave of water I was expecting, but after about 10 minutes the river was rising at a faster rate." DoC scientist Dr Harry Keys said the lahar generated a standing wave of about 3-4 metres in height as it passed down the Whangaehu River.
"It was nowhere near being a significant-sized one. The bund or embankment built to prevent a lahar flowing into the upper Waikato Stream and into the Tongariro River is intact? in fact, the lahar has come nowhere near it."
It flooded the area around the Tangiwai memorial and waters topped Strachan's Bridge, a small farm access bridge south of Tangiwai.
The state of the Crater Lake and what might remain of the tephra dam wouldn't be known until scientists could visit the crater, Dr Keys said.
While the river level was up because of the lahar it was contained without spilling on to the road.
Ruapehu District Council spokesman Paul Wheatcroft said there had been no major damage to infrastructure.
Police closed SH1 and SH49, but these were reopened late yesterday afternoon.
About 200 passengers on trains travelling between Wellington and Auckland were transferred to buses after a lahar forced the closure of a rail bridge at Tangiwai.
National rail operator Ontrack had engineers inspect the bridge but cleared it for use late in the afternoon.
The lahar sparked major interest from sightseers with dozens of cars flocking to Whangaehu to check for debris flowing down.
Conservation Minister Chris Carter praised all the agencies involved with managing the lahar.
"I am delighted with the way things have gone on Mt Ruapehu," he said. ? with NZPA