Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 30 November
to 16:00 01 December 1996
The current alert level is ORANGE

Activity at the volcano has remained at an increased level today with continuation of the swarm of volcano-tectonic earthquakes which started yesterday. The level of surface activity was low, with only a few rockfalls from the October 1 dome. However, further rock avalanches have occurred from the Galway's Wall in the past 24 hours and the wall remains very unstable. Further and bigger avalanches from the wall could happen at any time. A major collapse of the wall could expose hot, gas-rich magma from the lower sections of the dome, and trigger a lateral blast. This has the potential to cause major damage to St Patrick's and the surrounding areas, and the death of anyone in the area.

The October 1 dome is still growing, and further rockfalls and pyroclastic flows are likely down its northeastern and northern flanks. This means that the Tar River and Long Ground areas are especially dangerous and anyone entering in these areas is risking death. Continued collapse of the lava dome or catastrophic collapse of the Galway's Wall could lead rapidly to a further escalation in volcanic activity, and all residents of Montserrat are urged to follow the alert procedures and remain vigilant.

Inspections were made of the Galway's Wall during the day from the helicopter. Several new landslides were noted and new cracks are appearing each day. The wall remains highly unstable.

Seismic activity has been at a high level today, with continuation of a swarm of volcano-tectonic earthquakes. A total of 178 VTs have been recorded during the reporting period, all located at depths of less than 2 km beneath the crater. In addition to the VTs, 6 rockfall signals from the lava dome and one regional earthquake triggered the seismic network. Signals from rock avalanches on the Galway's Wall are now more easily distinguished and there were three which triggered the seismic network during the past 24 hours.

Excellent conditions enabled good views of the dome, a thorough dome survey and close inspection of the Galway's Wall to be made today. Dome growth appears currently to be concentrated in the northern sector of the October 1 dome, from where material might soon start spilling out and piling up against the Farrell's Wall.

An initial assessment of the possible tsunami (tidal wave) hazard from a catastrophic collapse of the Galway's Wall has shown that the only island under any significant threat is Guadeloupe, although even here, any tsunami is likely to be very small. In addition to the visit of Dr Barry Voight from tomorrow, several teams of French scientists will be on island during the week to help with further assessment of the landslide, lateral blast and tsunami hazards, especially with respect to how these activities might impact upon Guadeloupe.

Montserrat Volcano Observatory