Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 18 July
to 16:00 19 July 1996

The level of volcanic activity at the Soufriere Hills Volcano during this reporting period was relatively low, as it has been since 12 July. Small- to moderate-sized rockfalls from the flanks of the lava dome dominated activity.

There were 20 rockfall events detected by the seismic system, compared to 16 yesterday. The largest rockfalls occurred at 16:05 on 18 July and at 02:30, 06:22, 10:13 and 15:14 on 19 July. All except the 02:30 event produced small ash clouds which could be seen drifting to the west of the volcano, towards Upper Gages, Amersham and Plymouth. Hybrid and long-period events continue to be recorded at almost unchanged levels. There were 11 hybrid and 12 long-period events recorded in this reporting period, most of which were small in size. There were 4 VT earthquakes. Three of these were located at depths of less than 2 km close to Engish's Crater. The fourth was too small to be located accurately. Intermittent, relatively short-duration, low-amplitude broadband tremor was recorded by the Gages seismic station during most of the reporting period. There were two periods of near-continuous tremor, between 22:23 on 18 July and 01:50 on 19 July and between 09:50 and 10:20 on 19 July.

Visibility was poor for much of the day, although there were some periods when the lower flanks of the dome could be seen from the east and north. A field party working at Farrell's heard fairly-frequent rockfall activity and observed one rockfall which descended the northeastern flank of the dome.

COSPEC measurements of the SO2 flux in the plume were carried out during the afternoon. This data has not yet been processed. EDM measurements were made on lines in the eastern triangle. GPS measurements were made at stations on the northern side of the volcano. A combined GPS/gravity survey was carried out along a radial line to the north of the crater.

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