Government Information Service

The Volcanic Explanation
For The 24 Hour Period Ending 4 PM On Tuesday July 22, 1997
A Presentation Of The Government Information Services
In Conjunction With The MVO.

The alert level system has been revised by zones.

The Soufriere Hills Volcano Has been at about the same level as yesterday with rockfall the main seismic signals recorded. Very little activity was visible on the dome.

At about 5:00 am above Gages and Mosquito Ghaut and on the side further east, 3 incandescent chutes of hot rock were seen from the MVO. This indicates that dome growth is continuing above Mosquito Ghaut and Gages. The summit of the volcano was covered in low cloud today(Tuesday), but the flanks were clear for most of the day. A helicopter flight this morning indicated no new deposits in Gages, Galways, Tuitts Ghaut or the Tar River Valley. During the flight a small rockfall into Mosquito Ghaut was seen, this traveled about 500 m.

25 rockfalls, 5 long-period earthquakes , one volcano-tectonic earthquake and 2 regional events were recorded. The St. George's Hill seismic station recorded several periods of low amplitude broadband tremor today.

The recent pyroclastic flows and ash eruptions have not been associated with an increase in seismicity. Anyone entering the exclusion zone is at great risk. Further pyroclastic flows are most likely to occur in Mosquito Ghaut and Gages Valley but pyroclastic flows could also occur in Tuitts, Tar River Valley and White River. There has been no warning of the pyroclastic flows in Gages Valley and this makes Plymouth very dangerous. Belham River Valley could be the sight of pyroclastic surges or hot mudflows. These mudflows are at or near boiling point and travel very fast and may go further than pyroclastic surges.

Government Information Service