Jan 12 2009 - Volcanic activity in New Zealand 2008

White Island's crater lake began to re-form late in 2007, after nearly emptying itself earlier in the year. By February 2008 it had risen 6 metres and by the year's end a further 10 metres, although it is still about 10 metres below overflow. Fluctuations in the lake level, together with its temperature and sometimes colour, are common and reflect changes in the amount of volcanic steam and gases entering the lake, and to a lesser extent variations in rainfall. In June a magnitude 5.4 earthquake occurred close to White Island and there was some concern that this might trigger an eruption, as this has occurred at some volcanoes overseas; fortunately nothing further happened. In October an area of high temperature (about 100 °C) steam vents, which has been changing slowly for some years, became more active and for a while threw out a small amount of mud and unpleasant acid rain. Although there were minor changes White Island remained at Volcanic Alert Level 1 throughout 2008.

Ruapehu experienced a period of elevated lake temperature (about 35 °C), high sulphur dioxide and carbon dioxide gas emission, and moderate volcanic tremor activity from April to June. This activity is thought to have been a continued response to the significant eruption in September 2007. After a low Crater Lake temperature of 16 °C in August, the temperature increased to 30 °C in December, but without the high gas and tremor activity seen earlier in the year. Ruapehu remained at Volcanic Alert Level 1 throughout 2008.

In May 2006 Ngauruhoe began experiencing elevated seismic activity and the Volcanic Alert Level was raised to level 1 because of it. During the second half of 2008 the seismic activity declined and the Volcanic Alert Level was lowered to zero in December. The return to normal levels of earthquake activity means that an eruption in the near future is unlikely without a renewed period of earthquake activity or other changes.

Over the last few years continuous GPS (Global Positioning System) monitoring equipment has been installed around Lake Taupo to record ground deformation and complement the seismic and lake levelling networks. An episode of small scale deformation began in mid-2008, along with a pulse of earthquake activity. A similar event was recorded in late 2007, but without the earthquakes. It appears that periods of ground deformation, possibly a result of pressure in the magma or geothermal systems beneath the lake, are probably quite common at Taupo, but have only been seen with recent improvements in monitoring. The level of activity was insufficient to make any alert level change and Taupo remained at Volcanic Alert Level zero throughout 2008.