Jan 11 2011 - Volcanic activity in New Zealand 2010

No eruptive activity was recorded at any of the active volcanoes during 2010, similar to 2009.

The surveillance programme for White Island includes gas and water sampling, ground deformation and soil gas surveys and servicing. During the year the Crater Lake water level has fallen to about 14 metres below the overflow, however the temperature remains high at 57- 62 °C. Minor changes have been observed in an area of high temperature (118 - 200 °C) steam vents on the southern side of the Main Crater floor. These vents have been changing slowly for some years. The gas flux (measured from the air, from soil gas surveys and from the miniDOAS spectrometer) has remained low; carbon dioxide (CO₂₎ has ranged from 750 to 2,700 tons per day, while sulphur dioxide (SO₂) has ranged from 109 to 387 tons per day. The deformation survey confirmed continued uplift in the earlier part of the year, which has been recorded during the last 2 to 3 years, but this had stopped by the year's end. Volcano seismicity remained around typical background levels. The Volcanic Alert Level remained at Level 1 during the year.

Ruapehu Crater Lake temperatures started out low (20 - 25 °C) then warmed to over 30 °C later in the year. No eruptive activity was observed. Although activity has been low, gas flux has continued to vary during the year, with CO₂ ranging from 156 to 2,100 tons per day and SO₂ from 6 to 25 tons per day. Volcanic earthquake activity remained at low levels, as did volcanic tremor. Ruapehu remained at Volcanic Alert Level 1 throughout 2010.

Since early 2006, small low-frequency volcanic earthquakes have been present at Ngauruhoe. The level of seismicity has fluctuated over the year, with higher levels of activity in January, March, October, November and December. The highest levels were in January when activity reached 70 earthquakes per day. The Volcanic Alert Level remained at Level 0 during 2010.

Monitoring at Raoul Island has continued, with no anomalous trends having been observed in the temperatures or water levels of the Crater Lakes. The Volcanic Alert Level remains at Level 0.

Anomalous bore pressures and temperatures were reported from Rotokawa and Rotorua city in December. Water samples were collected from Rotokawa and show no changes from previous sampling. The Environment Bay of Plenty bores in Rotorua show a faster and stronger post-winter recovery, and the reported changes are attributed to that.

We continued to see evidence of small-scale eruptive activity at Monowai seamount on the Rarotonga seismic record during the year. No activity was confirmed by surface observations.

Small earthquakes have continued to occur in the Taupo Volcanic Zone, particularly offshore of Matata, south-west of Kawerau and at Waimangu, and along the Haroharo vent lineation within the Okataina Volcanic Centre. Not so many events have been located within Taupo Volcano, but activity continues to the south-west of the lake through Turangi to Lake Rotoaira. Events have also been recorded on the northern parts of Tongariro and around Ruapehu, in particular to the west of the volcano. No events have been recorded under Taranaki, but seismic activity continues to the west of the volcano.