A short, low-energy volcanic tremor was detected at Whakaari/White Island at 4am on Tuesday, June 1.
GNS Science's on-duty volcanologist said the signals recorded quickly returned to normal low levels.
Web cameras observed water filling the vents of the 2019 primary crater since May 18.
An observation flight on May 27 confirmed that the development of a small lake in the crater. Several steam and gas vents are now underwater.
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There is no evidence of new explosions around the crater.
Measurements taken in infrared and thermal imaging on other observation flights have confirmed the active vents are cooling significantly.
A bulletin from GNS Science said the amount of gas being released from the volcano has not changed much over the last few months. Whakaari continues to produce a weak-to-moderate gas and steam plume and this may cause weak acid rain downwind of the island as usual.
The level of the seismic tremor is reported to remain at background levels.
The Volcanic Alert Level remains at 1 and the Aviation Colour Code remains at Green.
GNS Science and the National Geohazards Monitoring Centre continue to monitor Whakaari for further changes in unrest.