On 14 February GeoNet reported that Tongariro remained quiet with no eruptive activity being detected since the explosion on 21 November 2012. Steam-and-gas plumes rose from the Te Maari Craters, and were unusually strong during the recent weeks possibly due to weather conditions. The Aviation Colour Code remained at Yellow (second lowest on a 4 four-color scale) and the Volcanic Alert Level remained at 1 (on a scale of 0-5).

Geologic Background. Tongariro is a large andesitic volcanic massif, located immediately NE of Ruapehu volcano, that is composed of more than a dozen composite cones constructed over a period of 275,000 years. Vents along a NE-trending zone extending from Saddle Cone (below Ruapehu volcano) to Te Mari crater (including vents at the present-day location of Ngauruhoe) were active during several hundred years around 10,000 years ago, producing the largest known eruptions at the Tongariro complex during the Holocene. North Crater stratovolcano, one of the largest features of the massif, is truncated by a broad, shallow crater filled by a solidified lava lake that is cut on the NW side by a small explosion crater. The youngest cone of the complex, Ngauruhoe, has grown to become the highest peak of the massif since its birth about 2500 years ago. The symmetrical, steep-sided Ngauruhoe, along with its neighbor Ruapehu to the south, have been New Zealand's most active volcanoes during historical time.

Source: GeoNet