Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 16 July
to 16:00 17 July 1996

The level of volcanic activity at the Soufriere Hills Volcano during this reporting period was similar to that during the previous twenty four hours. Small- to moderate-sized rockfalls from the flanks of the growing lava dome dominated the activity.

There were 24 rockfall events detected by the seismic system, compared to 15 yesterday. The largest rockfalls occurred at 18:17 on 16 July and 13:05 on 17 July. The first of these generated a small amount of ash which could be seen in the plume and cloud drifting over the Upper Gages area. The second generated a small ash cloud which rose to a height of 1,000 to 2,000 feet above the crater and drifted west over Plymouth. There were 14 hybrid and 8 long-period events recorded, most of which were small in size. Short bursts of low-amplitude broadband tremor were recorded by the Gages seismic station during much of the day. This was most probably related to increased steam emission in the Crater.

Visibility was good at times and a number of observations of the dome were made. There was vigorous steaming from most of the dome. A small amount of new material appears to have come over the Gages Wall. There was also a small amount of new material against the Galways Wall. Very little rockfall activity was observed. Observers on Perche's Mountain noted that most of the rockfall activity appeared to be on the southwest flank of the dome. A small block and ash flow was seen coming down the eastern flank of the dome at 11:57.

EDM measurements were made today on the lines in the eastern triangle. The data is still being processed. A combined GPS and gravity survey was carried out on a radial line on the western flank of the volcano. A new benchmark was installed on Perche's Mountain and will be used for both the GPS and gravity surveys.

No COSPEC measurements were made today.

The Soufriere Hills Volcano is still considered to be highly dangerous to people and property on it's eastern and upper western flanks. Visits to the evacuated zone must be kept to a minimum. The Tar River and Long Ground areas to the east and upper Fort Ghaut, Gages Village and Upper Amersham areas to the west are all extremely dangerous. All access roads to these areas remain closed and people should not enter these areas under any circumstances. If they do, they put themselves and others at direct risk of serious injury or death.

Montserrat Volcano Observatory