Weather might have caused second eruption in Rotorua

6:10 pm on 30 November 2016

A second hydrothermal eruption in Lake Rotorua might be weather-related, according to a GNS volcanologist.

The geyser of water observed this afternoon was about 1m in height and about 3m in diameter.

An earlier eruption, on Monday morning, caused a much larger geyser, which shot several metres into the air.

A video of today's eruption was shared on the Steam n' Mud Rotorua Facebook page:

Brad Scott, who works for GNS Science at Wairakei, said the second eruption occurred in one of Lake Rotorua's bays near the Ohinemutu village.

It might have arisen as a result of a low-pressure weather system, which came through the area about 3pm, he said.

"When you lower the barometric pressure, you basically take the weight off the geothermal system and that allows more steam to come through. And if a hot spring is on the verge of erupting, it can let it erupt."

Mr Scott said those living at Ohinemutu Village were unlikely to be affected by the activity.

"The village here is built over an active geothermal system and they are living in a very dynamic area. where the event has occurred is a good 150m or more from the nearest houses, so I think the people are pretty safe in their normal built environment."

He said Rotorua's geo-thermal system was slowly recovering from over-use in the 1970s and 1980s, and this week's activity may just be part of that.

The Rotorua Lakes Council said a build-up of steam pressure caused Monday's eruption and, while the geyser was spectacular, there was nothing to worry about.

GeoNet described the earlier eruption as small-scale, and said it produced a geyser between 7m and 30m.

Mr Scott said at the time there was only a low probability it could have been caused by the recent earthquake sequences in Kaikōura and the East Cape.