Scientists say temperature tests from steam plumes at Mount Tongariro show there is unlikely to be an eruption of magma in the near future.
The mountain was quiet on Friday night, while White Island off the coast of Whakatane, is still active.
GNS Science has established three possible scenarios:
Either small steam eruptions similar to the event on Monday night will continue
There will be a bigger, magmatic eruption, or
Mt Tongariro will go back to sleep.
Professor Colin Wilson of Victoria University says temperature tests on the plume of steam from the volcano show it is not hot enough to be coming from magma.
He says steam from magma would be closer to 700 - 800 degrees Centigrade.
Professor Wilson says Massey University scientists are testing ash gathered 200 metres from the crater to find out if levels of arsenic and fluorine could affect water supplies and the health of livestock.
GNS Science says the volcano is expected to stay at its current low level of activity for the next week.
White Island could continue erupting for several months, emitting low levels of ash.