article: Jul 4 2006 - Update on Ngauruhoe Observations

Since our last update three weeks ago the number of volcanic earthquakes recorded near Ngauruhoe has varied between approximately 20 and 40 per day. This level remains significantly above that normally recorded in this area. Using data from additional seismographs installed around Ngauruhoe we have been able to refine the location of the earthquakes to within about 1 km of the surface beneath the northern flank of Ngauruhoe. The largest earthquakes are approximately magnitude one.

Measurements of volcanic gas concentrations and temperatures made at the summit area of Ngauruhoe on June 26 were both normal, and show no significant changes from those made on June 8 and in 2003. The maximum fumarole temperature near the summit was 85°C.

We have recorded no other signs of unrest at Ngauruhoe. We have no evidence that an eruption of Ngauruhoe is imminent.

We will continue to operate the additional seismographs to help refine earthquake locations and measure volcanic gas concentrations and fumarole temperatures. We will monitor Ngauruhoe closely and will release updated information as it is available.

The accompanying graph shows the number of earthquakes recorded per day at Ngauruhoe since the start of May. Shown below are pictures of staff retrieving portable seismographs from beneath 1.5 m of snow and a picture of the summit fumarole.