Further eruptions at Tongariro may occur with "little or no warning", according to a GNS vulcanologist.
GNS Science said today that activity at Tongariro remains low, but steam and gas plumes from the Te Maari area are always present.
"Tongariro has had no eruptive activity since the explosion on 21 November 2012."
Earthquake activity has been negligible since before the November 2012 eruption and the flux of volcanic gases has remained relatively stable for several months.
"After the eruption in November 2012 we had to consider the possibility that Tongariro might have entered an eruptive episode similar to one that occurred in the 1890s," GNS vulcanologist Brad Scott said.
"However, we do not know if further eruptions will occur or if the Te Maari crater area will just quietly discharge steam for several years. If further eruptions do occur we have to expect that they might have little or no warning."
GNS Science head vulcanologist Gill Jolly said it was difficult to be certain what would happen in the next few months.
"We expect that eruptions substantially larger than that in August 2012 should give us some warning signs."
In recent weeks GNS Science has received several reports describing unusually strong steam emission from the Te Maari crater area.
"Some of these can be attributed to weather conditions but others probably reflect natural variability in the steam and gas emission rates."
- Manawatu Standard
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