According to the local observatory Geonet, observation flights on 15 July and today confirmed that the 2019 Primary Crater remains flooded associated with minor steam and gas activity around the area.
The volcano is currently characterized with only near-constant venting of steam emissions, formed in early June on the north side of the 2019 crater, and continue at low levels. There is no evidence of eruptive activity.
A gas flight on 20 July confirmed that the amount of gas being released from the volcano has not changed significantly over the past few months.
Thermal IR measurements on 15 July ranged from 498 to 654°C for vents on the 2019 lava extrusions (domes) and show a dramatic rise from 110-111°C measured there in late May-June. The high temperatures are like those measured in early-mid 2020.
The seismic activity including volcanic tremor has generally remained at low levels during the past months but there have been exceptions. On 2 June there was a short-lived tremor episode. Discrete acoustic signals were recorded on 18 June, and then overnight on 19-20 June some sharp increases and decreases in acoustic signal occurred with related geysering in the new vent north of 2019 Crater. A 15-minute-long low frequency volcanic earthquake was recorded on 30 June.
A night-time glow, reflecting higher vent temperatures, has been present since the 30 June earthquake.
For several months ground elevation change derived from the InSAR satellite data has consistently showed minor uplift of an area near the 2019 Primary Crater. However, in the past few weeks a mix of signals has indicated both subsidence and continued uplift.
Recent observations and data confirm volcanic unrest continues with some variability. As the Main Crater fills with water and the 2019 Primary Crater became flooded, there have been changes. As expected, vent temperatures initially cooled and then gas was being pushed sideways around the lava domes and changes in ground level were measured. Now, high temperature gas from magma at shallow depth is again reaching the surface through vents in the 2019 lava extrusions. The exact mechanism driving these changes is uncertain, but magma is involved either through its subsurface movement, or by new release of gases from a stationary body of magma.
The Volcanic Alert Level remains at 1 and the Aviation Colour Code remains at Green.
Source: GeoNet New Zealand volcano activity update 20 July 2021