Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 1 December
to 16:00 2 December 1996
The current alert level is ORANGE

Activity at the volcano increased today. The VT earthquake swarm intensified and there is more evidence of serious instability of the Galway's Wall. 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 everyone in the area. The Tar River and Long Ground areas are still threatened by pyroclastic flows and anyone entering these areas is risking death. All residents of Montserrat should follow the alert procedures and remain vigilant.

Several inspections were made of Galway's Wall during the day from the helicopter. Two substantial cracks were seen cutting across Chances Peak, on the Galway's Wall side. These cracks can be traced for over 300 ft and show vertical movements of several centimeters. It is thought that these cracks penetrate vertically downwards through the northern end of the wall. Although no major landslides were witnessed, there was clear evidence of further landslide activity from the Galway's Wall. The wall appears to be becoming more unstable every day and catastrophic failure may be imminent.

Excellent visibility allowed observations of the dome both today and last night. Very little surface activity was seen and there were very few rockfalls from the dome. The small central spine on the new dome has grown noticeably. One small rockfall at 3:10 pm generated a very small ash cloud.

The VT earthquake swarm which started on 30 November continues. 165 VT events were recorded today, located at shallow depths beneath the crater. The size of the events has increased noticeably during this reporting period. 12 rockfall signals were recorded today. Most of these were from landslides on the Galway's Wall. The number of signals suggests an increase in landslide activity since yesterday. Further analysis of the seismic records is underway to verify this.

The EDM reflector on Chances Peak was restored today. Also, installation of reflectors on the northern end of the Galway's Wall was undertaken to try to better measure movements on the wall. The lines to Chance's Peak show some shortening since last measured in October at a rate higher than the previous trend.

Dr Barry Voight of Pennsylvania State University arrived on Montserrat this morning. He will be assisting with the assessment of Galway's Wall and its stability. Mr Michel Feuillard, Head of the Volcano Observatory of Guadaloupe arrived on Montserrat this afternoon with three scientists from BRGM; Mr Herve Traineau, Mr Olivier Sedan and Mr Simeon. They will be discussing the stability of Galway's Wall and the possibility of a large landslide generating a tsunami which could reach Guadeloupe.

Montserrat Volcano Observatory