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Researchers install lahar measuring equipment at Ruapehu Crater Lake - 12/01/2007

Scientists from GNS Science and the Department of Conservation installed a set of lake-monitoring equipment on Mount Ruapehu last weekend.

The instruments include a sensor to measure the rate of fall in lake level during any break-out event and a fixed digital camera overlooking the tephra dam to record its erosion.

The equipment, purchased by the GeoNet project which is run by GNS Science, had been monitoring the crater lake on White Island. It was relocated due to the rising water levels at Mt Ruapehu. A professional kayaker from Kiwi River Safaris paddled out onto the lake to install the level sensor.

“By knowing the shape of the lake basin and measuring the rate and amount of drawdown, we can reconstruct how quickly the water escapes during initiation of a lahar,” said project leader for GNS Science Dr Vern Manville.

“We can compare this with measurements taken further downstream to see how the lahar evolves.”

Ruapehu Crater

The equipment is the second in a series of planned deployments that are being made over the summer months, to obtain as much information as possible from any lahar along the expected flow path.

Late last year researchers installed electronic equipment in the Whangaehu Valley to measure the speed and depth of a lahar.

A lahar could be caused by a collapse of the tephra barrier at the Crater Lake, or it could be triggered by a volcanic eruption. Lahars are common on Ruapehu and the data obtained from this research could have immense value worldwide.

The research is funded by a Royal Society Marsden grant, the Earthquake Commission, and the Foundation for Research Science and Technology, and is being undertaken jointly with Massey University.