Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 29 July
to 16:00 30 July 1996

Activity at the Soufriere Hills Volcano remained at a relatively elevated level, although not as high as during the peak yesterday afternoon. There were many rockfalls and a few small pyroclastic flows into the Upper Tar River Valley. There were also several periods of occurrence of repetitive hybrid events which have been associated in the past with periods of dome growth.

Eighty nine (89) rockfall events were recorded in this reporting period. Only one of these was associated with an ash cloud, at 13:23 today. Repetitive hybrid earthquakes have been occurring since 28th July. At times, these have been so large and frequent that they resemble continuous seismic tremor. Up until the pyroclastic flow activity yesterday afternoon, episodes of hybrid activity were occurring very regularly at approximately four hour intervals. After the pyroclastic activity, the spacing between episodes shortened to about 3 hours. This type of activity has been associated in the past with increased dome growth. There were 6 long-period events and 20 VT events recorded during this reporting period, levels very similar to yesterday.

Visibility was poor for most of the day. Observations of the lower flanks of the dome showed that the rockfall activity was still concentrated on the northeast flank of the dome. A helicopter inspection in the late afternoon showed that the flows yesterday afternoon occupied the entire Tar River Valley area, burning most of the vegetation.

Further GPS measurements were made today, but this data is not yet available. EDM measurements were made at stations in the eastern triangle: Whites, Long Ground and Castle Peak. The results from yesterday's measurements (29 July) show that the Tar River to Castle Peak line shortened by 17.5 cm since the 05 July while the Whites to Castle Peak and Long Ground to Castle Peak lines shortened by about 3 mm and 1.3 cm respectively compared to data obtained on 26 July. Today's measurements indicate that the Whites to Castle Peak and Long Ground to Castle Peak lines lengthened by 1 cm and 2.3 cm respectively. The height to the top of the dome was measured today as 3029 ft, compared to 3088 ft obtained on 12 July.

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