Government Information Service

The Volcanic Explanation
For The 24 Hour Period Ending 6 PM On Sunday December 29, 1996
A Presentation Of The Government Information Services
In Conjunction With The MVO.

The new dome is growing very quickly on top of the October 1 dome with rockfalls and small pyroclastic flows continuing. The seismic activity was mostly hybrid events, there were 138 hybrid, 6 long-period and 2 volcano-tectonic earthquakes. Also there were 36 rockfalls today (Sunday). The number of events were lower today but the individual events were bigger. Large collapses of the dome could occur quite suddenly and this could generate large pyroclastic flows into the Tar River Valley. The Gallway's Wall is still unstable and this could possibly lead to rapid escalation and explosive activity.

Due to low cloud cover observation was limited today, but it appears that rockfalls are continuing regularly. Last evening excellent conditions showed that the northeastern flank was glowing, with avalanches of incandescent blocks. The new dome is very dark in colour and smooth compared to older domes. A detailed analysis will be carried out when a sample is obtained.

COSPEC measurements made yesterday show a flux of 325 tonnes of sulphur dioxide. There has been no noticeable change since the mid-November reading.

NO EDM measurements were taken today. Water and gas samples were collected today as a part of routine environmental monitoring.

An attempt to measure the temperature of the new dome last evening was not possible as the instruments needed to be closer. Observations during the day suggest that the dome lava my be hotter than previous dome lava.

The alert level remains at ORANGE which means there should be on one in Zones A,B,C, and D on the revised volcanic alert map for December.

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