Science Alert Bulletin NGA-2006/06 - Ngauruhoe Volcano

Published: Wed Nov 1 2006 5:00 PM

Volcanic Alert BulletinNGA-2006/06
Ngauruhoe Volcano
Volcanic Alert Level remains at 1

1 November 2006, 4:00 pm - Update on activity and observations at Ngauruhoe

Seismic activity at Ngauruhoe remains elevated. Measurements of temperature and volcanic gas concentrations at the summit area remain normal. Recent reports of steaming in the summit area are attributed to cloud rather than to any kind of volcanic activity. We have no evidence that an eruption is imminent, but will continue to monitor the volcano closely.

Alert Status

The Volcanic Alert Level remains at Level 1

Since our last update (27 July) elevated volcanic earthquake activity has continued at Ngauruhoe. Up to 30 earthquakes per day have been recorded since the activity began in late May, significantly above that normally recorded at Ngauruhoe. The largest earthquakes are about magnitude 1. Observations suggest that the earthquakes continue to occur within about 1km of the surface beneath the volcano’s northern flank.

Measurements of volcanic gas concentrations and temperatures were made at the summit area of Ngauruhoe today. These data have not changed since the unrest began in late May, and are similar to measurements made in 2003. The maximum fumarole temperature near the summit is about 85°C.

Over the last two months we have received several reports of steaming from an area of the summit where steaming does not normally occur. We have examined this area and can find no evidence for any new features that may have produced the steam that was reported. We conclude that the reports can probably be attributed to cloud.

We have recorded no other signs of unrest at Ngauruhoe, and have no evidence that an eruption of is imminent. We will continue to operate an additional seismograph to help monitor the earthquakes and we will measure volcanic gas concentrations and fumarole temperatures as necessary. We will release updated information as it is available.

Steven Sherburn
Duty Volcanologist