A burst of ash was expelled from Whakaari/White Island over the weekend but the volcanic alert level remains at level 2.
It followed a notable volcanic earthquake recorded at Whakaari/White Island on Thursday evening.
Geonet says there was a short-lived period of about two minutes where ash emission was observed from the active vent area of the offshore volcano.
It took place at about 7.40am on Sunday.
The emission was not visible in camera images captured from Whakatāne.
"Based on the short duration of the activity, it is unlikely to have produced a plume large enough to create any ashfall, even on the island," Geonet said.
At 7pm on Thursday a volcanic earthquake took place at the volcano for about 10 minutes but was not accompanied by any eruptive activity.
"No relationship has been established between the volcanic earthquake and the minor ash
emission three days later," Geonet said. "Other seismic activity at the volcano has been minor.
"Webcam images continue to show night glow, suggesting that temperatures in the active vent area probably remain around 500-600°C, like recent observations.
"Satellite radar data continue to show small amounts of ground deformation around the active vent and lake area."
The recent observations do not change the recent interpretations a fresh magma intrusion to shallow levels has occurred since June.
The ash emission may be related to shallow magma beneath the active vents, however, its short duration suggested unstable material falling into the active vent then fragmented and ejected by gas pressure may be a more likely explanation, Geonet said.
"The current level of activity is consistent with moderate levels of unrest," Geonet said. "As such the Volcanic Alert Level remains at 2 and the Aviation Colour Code remains at Yellow.
The Volcanic Alert Level reflects the current level of volcanic unrest or activity and is not a forecast of future activity.
"While Volcanic Alert Level 2 is mostly associated with volcanic unrest hazards (including discharge of steam and hot volcanic gases, earthquakes, landslides and hydrothermal activity), potential for eruption hazards also exists and eruptions can still occur with little or no warning."
In December 2019, 22 people lost their lives – and more than 25 other people suffered serious injuries – after the once-popular tourist attraction Whakaari/White Island erupted.