Mt Ruapehu is experiencing tremors and its temperature is rising, but a volcanologist says while the volcano's chances of erupting are increasing, any eruption is likely to be small.
"The chances of eruption have clearly increased as we've gone through into this heightened unrest period," GNS volcanologist Geoff Kilgour told Newshub Live at 11:30am. "As to exactly what the probability is that's very, very difficult to say."
Mt Ruapehu is in its sixth week of raised volcanic activity with continued high levels of volcanic gas emissions and strong tremors.
GNS said the volcano has exhibited the strongest volcanic tremor in two decades, but an eruption would likely be confined to the lake basin.
On Tuesday morning a steam plume rose from Mt Ruapehu into the air. Kilgour explained the plume was down to the temperature of the lake.
"The cool calm conditions that were around the volcano basically allowed that steam plume to rise."
Kilgour said he thinks magma pushing its way towards the surface is driving the period of unrest.
"What we can say though is that if magma is rising to the surface, which we believe it is… Any eruptions that start will likely be very small."
"But it is very, very unlikely for any, at least initial eruption, to basically break through and generate a large eruption that impacts on to the ski field or further afield."
