Ash from the Tongariro eruption will be tested in Palmerston North today as scientists try to learn whether further volcanic activity is possible.

The first eruption on the mountain for more than 100 years could be a standalone event, or possibly a precursor to several days, weeks or even months of activity.

A Massey University vulcanologist said ash samples would be tested today to help understand the nature of Monday night’s event and to help predict further activity.

‘‘It gives us insight into what’s happening,’’ Dr Jon Procter said.

‘‘If there is new magma then we will find glass shards in the sample... if this is found there could be more eruptions.’’

Monday’s eruption closed state highways, disrupted flights and covered part of the Central North Island in up to 15 millimetres of volcanic ash.

Rocks were flung up to a kilometre from the mountain and the ash cloud reached Napier and Hastings.

Niwa said the ash cloud from the eruption was 25km long and 15km wide. It moved east, travelling 250km in four hours at an average speed of 18 metres per second.

Three active vents were spotted on Tongariro  yesterday though Geonet said the gases issuing from them did not contain ash.

Numerous domestic flights were delayed or cancelled yesterday, with no flights to Hawke’s Bay. Several flights to or from Palmerston North were cancelled.

An Air New Zealand spokesperson said passengers should check the company’s website for flight information over the coming days.

Skifields on neighbouring Mt Ruapehu are open but tracks and huts on Mt Tongariro are closed until further notice.

The NZ Army’s Central Plateau facilities were unaffected.

Major Pat Hibbs of the NZ Army’s Training and Doctrine Command said: ‘‘We had a number of people training in the region, who were evacuated from the training area as a precautionary measure once the eruption occurred.

‘‘There has been no sign of any ash in the Waiouru Military Training Area and as a result there is no risk to the health of any of our personnel.’’

The Desert Road and a section of State Highway 46 were closed for several hours yesterday.

Motorists who were on the Desert Road during the eruption reported low visibility caused by ash fall and flashes of light from the mountain.

Inspector Brett Crowe of Taupo police said they would work closely with the experts to determine what assistance they could provide.

The last time Tongariro erupted, volcanic activity lasted from November 1896 until October 1897. The mountain also erupted in 1869 and 1892.

Dr Procter said Tongariro’s awakening from its long slumber came after several weeks of unrest on the mountain.

‘‘It’s not a surprise as it’s still an active volcano,’’ he said.

He said GNS had been noticing changes on the mountain and there had been reports of a stronger smell of sulphur in the area.

Yesterday, Dr Procter surveyed the crater from a helicopter.

‘‘We saw a steam plume coming from a vent but we couldn’t see that vent as it was covered in low cloud.

‘‘We also saw the extent of where the ash has exploded. It’s stretched about 10 kilometres. It’s pretty cool to see this in your backyard.’’

Dr Procter said there was no connection between Tongariro and the eruptions on White Island last week.

- © Fairfax NZ News

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