Government Information Service

The Volcanic Explanation
For The 24 Hour Period Ending 4 PM On Friday July 18, 1997
A Presentation Of The Government Information Services
In Conjunction With The MVO.

The alert level system has been revised by zones.

The level of activity at the Soufriere Hills Volcano today (Friday) was at the same level as yesterday and was dominated by rockfall signals.

The clear conditions allowed good views of the dome, except for the summit.. Observations from the helicopter show that the scar from the 25th June activity has almost completely filled in. Material from the new dome is spilling onto the north-eastern flank of the pre-June 25th dome. All areas above Whites Ghaut are being built up to the rim of the crater and rockfalls will probably feed into the ghaut. Small pyroclastic flow deposits were seen in Galways, Gages, Mosquito Ghaut and the eastern flanks of the dome. A few small rockfalls were seen in Gages Valley as well.

29 rockfalls an increase from yesterday (Thursday), 3 long-period earthquakes and 2 hybrid events were recorded. The St. George's Hill seismometer recorded several periods of low level tremor throughout the day.

The EDM measurements of line lengths between Waterworks and Lees Yard with the Total Station was made twice. Again no change was seen.

The recent pyroclastic flows and ash eruptions have not been associated with an increase in seismicity or tiltmeter readings. 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.

Today marks the 2nd Anniversary of the Soufriere Hills Volcano erupting. There have been 105 million cubic metres of fresh rock produced, 60% has formed the lava dome. The rest has been deposited as pyroclastic rock fragments on the sides of the volcano and in the sea. Over 10,000 volcanic earthquakes have been recorded, but very few have been felt locally. The MVO wants to assure Montserratians that they will continue to do their best to provide adequate information and advise on the ongoing eruption.

Government Information Service