Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 26 November
to 16:00 27 November 1996
The current alert level is AMBER

Observations of Galway's Wall this morning confirmed that failure of all or part of the wall is a real possibility. This could trigger a directed blast, maybe without any warning, which would devastate St. Patrick's and the surrounding area. People must not enter any part of zone A, in particular the area south of Gingoes Ghaut. The dome is still in a highly dangerous condition and rockfall activity could escalate at any time. This means that the Tar River and Long Ground areas are especially dangerous and anyone entering or remaining in these areas is risking death.

Inspections were made of the outside of Galway's Wall this morning, from the ground and the helicopter. There had clearly been further rock avalanches from the wall since the last inspection yesterday. Some of the fractures in the wall seemed to have grown, and the wall looked extremely unstable. Several small avalanches were observed, and these were followed by a large avalanche from the upper part of the wall at 11:10 a.m. This event was recorded as a large rockfall signal by all the seismic stations. No further observations were possible, as field parties made a rapid withdrawal from the area. Attempts to establish monitoring positions were abandoned. Since 11:10 am, no further avalanches have been recorded by the seismic networks.

The small swarm of VT earthquakes which started two days ago continued, although there has been a gradual reduction in the size and rate of the events. 50 VT events were recorded in this reporting period. These were all located at shallow depths beneath the crater. Four rockfall signals were recorded today. Two of these were from avalanches on Galway's Wall, at 03:04 and 11:10 a.m. This is the first time Galway's avalanche signals have been identified in the seismic records, and today's avalanche is the largest to date. The other two rockfalls were relatively small dome events. Tremor has been recorded on the Gages seismometer throughout the reporting period.

A GPS survey of the network which straddles the volcano was completed this afternoon. This survey was started yesterday. The results have not yet been processed.

Further observations of the Galways Wall will be made tomorrow from the helicopter. At the moment it is considered too dangerous to approach the Galways area by road. If the wall stabilises, it may be possible to allow short visits into the evacuated area during the next few days. In the meantime, however, the situation must be regarded as extremely serious, and nobody should venture into the area.

Montserrat Volcano Observatory