White Island (Whakaari); Crater Lake reforming and an earthquake swarm. Overall the volcano remains quiet.

Published: Mon Mar 19 2018 4:00 PM

GeoNet monitoring teams visited White Island last week and found it quiet. Over the weekend a small earthquake swarm has occurred nearby. No changes in activity are apparent after the swarm.

Observations during a visit to White Island on Wednesday last week confirm that the volcano remains quiet. The monitoring team undertook a ground deformation survey, measured fumarole and vent temperatures, sampled springs and the Crater Lake. These activities are part of the routine monitoring undertaken at White Island every 3 months. These visits complement the seismic, acoustic, GNSS, web camera and gas data that are collected continuously.

The most significant change is the reappearance of a Crater Lake on the floor of the Active Crater area. This appears to be a response to the rainfall from the recent cyclones. The lake temperature is relatively cool at 27 ºC, and we were also able to sample the lake. The lake was last sampled in August 2017.

The newly formed Crater Lake at White Island

The newly formed Crater Lake at White Island

Temperatures of both the Dome vent in the active crater and Fumarole 0 on the Main Crater floor continue to decline. The Dome vent is now 128 ºC, down from 157 ºC in December 2017. While Fumarole 0 is down from 144 to 138 ºC. Spring and stream flows have also declined, which is consistent with the lower water level in the Crater Lake or following periods with no lake present. The ground deformation survey also shows subsidence towards the Active Crater of 2-5 mm per month.

The seismic activity has been low in recent months, however there was a sequence of small earthquakes near the island over the weekend. The largest earthquake was M3.3 at 11:37am on Saturday 17 March. We have not detected any changes at the island related to these earthquakes.

The seismic record on Saturday March 17 at White Island

The seismic record on Saturday March 17 at White Island

White Island is always capable of a new eruption at any time, often without any useful warning. We continue to monitor the volcano for possible renewed activity. The Volcanic Alert Level remains at Level 1. The Aviation Colour code remains Green.