Tongariro still restless

A 3km exclusion zone has been set up around Mt Tongariro after it blew rock and ash high into the air on Wednesday, with experts warning there is a very real chance of it erupting again.

GNS Scientist Nico Fournier said: "It has been a quiet night in the park. On the GeoNet website, people may have noticed some earthquake-like spikes in rapid succession at some stations on Thursday evening. These were caused by thunderstorm and lightening in the Tongariro National Park. They were not real earthquakes and were not caused by any of the volcanoes."

GNS Science yesterday cancelled its national advisory after the eruption from the Te Maari crater.

However, it says there remains a "significant probability of a sudden eruption within the next week".

Should a further eruption occur, a new national advisory or warning would be issued.

Signs of volcanic activity have settled but experts continue to monitor the mountain for changes.

GNS Science did not record any change of volcanic activity at Tongariro overnight but experts say Tongariro can still erupt at any time with little or no warning.

Thick grey smoke, gas and ash spewed 4km into the sky from Te Maari vent on the western side of the mountain during the unexpected eruption just before 1.30pm. It is the same place where Tongariro erupted in August, for the first time in more than a century.

GNS volcanologist Brad Scott said people up to 400km away could expect to smell sulphur from the volcano in the coming days but that was nothing to be concerned about.

The Department of Conservation has closed its tracks within a 3km radius of the crater.

The Tongariro Crossing would remain closed for at least the next three days.