‘Medium’ chance of another eruption

Volcanic tremor has continued to increase at Whakaari/White Island yesterday, with GeoNet saying there is a ‘‘moderate likelihood’’ of another eruption in the next 24 hours.

In an update just before 5pm yesterday, GNS Science duty vulcanologist Craig Miller said scientists had reviewed all available data at 11am.

They calculated there was a

40-60 per cent chance of an eruption that could have an impact outside the vent area on the volcano, within 24 hours.

As a comparison, an estimated

0.1-0.2 per cent chance of an eruption for a 24-hour period was calculated in late October, before the alert level for the island was raised to 2.

Since the 11am expert judgment, volcanic tremor had continued to increase.

In an earlier GeoNet update, around 10.30am yesterday, Miller said volcanic tremor had ‘‘significantly increased’’ during the morning ‘‘indicating that volcanic gas pressures remain high’’.

‘‘This has been accompanied by vigorous steaming and localised mud jetting in several of the craters created by the eruption on Monday,’’ Miller said.

GNS describes volcanic tremor as a small ground vibration that can be an almost continuous signal.

It can be caused by hot volcanic gases escaping from magma and passing through cracks on the way to the surface.

Miller said monitoring equipment on the island continued to function, providing continuous data on the volcano’s activity.

In a bulletin on Tuesday, GeoNet said that in the next 24 hours there was an equal chance of no eruption, or of an eruption that was smaller or of a similar size to Monday’s event.

At the time it said there was a high level of uncertainty associated with that estimate, and it was working to reduce the uncertainty.