New Zealand's had only a few well-observed eruptions, so Japan's findings are helping Kiwi scientists with their predictions.
A GeoNet volcanologist described the event as "a vigorous steam-gas plume above the island".
The Volcanic Alert Level has been increased to 3.
It was the biggest atmospheric explosion in 100 years.
GNS Science principal scientist Graham Leonard said the volcanoes weren't talked about much.
An international team of scientists looked at how far fires could spread if sparked by a volcanic eruption.
The recent number and size of earthquakes is within GeoNet's expectations for a volcano at minor volcanic unrest.
"In the event of the Hunga eruption [it] showed that there's a lack of early warning from international tsunami warning systems and models."
An international study suggests New Zealand is underestimating the damage caused by volcanoes.
