A new crater has been formed on White Island as a result of Wednesday's eruption.
The site of the eruption was seen for the first time during an aerial inspection and the new crater, which has formed in the north-east corner of the 1978/90 Crater Complex, was glimpsed.
No vent was visible in this area before Wednesday.
GNS said significant collapse had occurred around the area and post-eruption land sliding was also present. Hot translucent gas had been emitted from the new vent.
Read more: White Island eruption overnight
Gas output is slightly elevated but well within the range of recent measurements, it said.
The volcanic alert level remained at level two.
GNS has said preliminary analysis of the eruption deposit suggested little or no new magma (lava) was ejected.
Laboratory analysis of the eruption deposit collected from the web camera site on the north rim has confirmed that most of the ash was strongly hydrothermally altered old rock material. No evidence of new, juvenile magma was found.
GNS said this suggested that no new lava material had been erupted and that the eruption was likely driven by steam and gas, like the eruptions in 2013 and 2013.