For Those Who Ask About Thermal Activity

Not Far from Recent Small Eruption


190405ac1 Geothermal Eruption.
Huge geothermal eruption spews rocks into the sky
20.04.2005

By REBECCA DEVINE in Rotorua

When his cows started stampeding up the hill, Reporoa (name of the area btw) farmer Phil Morgan knew something wasn't quite right. But he couldn't have imagined the huge geothermal eruption which was taking place just behind him - throwing huge stones into the air and leaving a crater more than 50 metres wide.

Yesterday morning's eruption on Department of Conservation land near Tutukau Rd is believed to be one of the biggest in New Zealand in the past 50 years. It was bigger than the massive eruption at Rotorua's Kuirau Park in 2001 and has amazed a local geologist who described it as "a real beauty".

Mr Morgan said he turned around after the cows started stampeding and saw "a massive cloud heading up into the heavens". He said while the area had always been a geothermal site, he never had any inkling it would erupt the way it did.
"It hurled some big rocks a fair distance so it must have had a bit of grunt."

Geologist Ashley Cody was called to the farm after the eruption and was stunned by the extent of it. Mr Cody said the rocks that were thrown out of the crater were up to 60 centimetres in diameter and more than a hectare of land had been destroyed. The land within 20 or 30 metres of the crater was covered with ash and mud more than four metres thick. About a hectare of land has been left barren.

Mr Cody said it was both unusual and exciting to see such an event as they often happened when nobody was around.
"It is pretty rare to see an eruption on this scale."

While the major eruption came about 10.30am the area was still erupting at 3.30pm yesterday with stones being shot about 15 metres into the air and the steam column rising almost 50 metres. Mr Cody said geologists would be keeping an eye on the eruption and it was likely it would weaken as it lost its energy. This could take hours or even days.

It was lucky the eruption happened in the Department of Conservation's scenic reserve and not in an area where there were people. Mr Cody said it was possible that had someone been within 20 metres of the eruption, they "may have come to grief".

Before the eruption, head-high blackberry covered the land but now there was "not a skerrick of vegetation" left. The eruption has blocked the neighbouring stream which is expected to "run muddy" for days.

Mr Cody said while the area was not really thought of as a place for eruptions, it had been heating up over the past year, with trees dying and new springs breaking out. An almost identical eruption happened in the area in 1948.

There had been no obvious triggers for the eruption, such as earthquakes, heavy rain or changes in air pressure.
"Almost every geothermal field does this from time to time."

Mr Cody said he would be returning to the area in the next few days to keep an eye on the activity but didn't think other farmers in the area needed to be too worried about it. Meanwhile, Mr Morgan said he would be carrying on his normal farm duties today after yesterday's excitement.