Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 2 December
to 16:00 3 December 1996
The current alert level is ORANGE

Because of increasing concern over the volcano and particularly the condition of Galway's Wall, the evacuation of Zones A, B , C and D is being strictly enforced. No access is allowed to these zones until further notice.

Activity at the volcano increased again today. The VT earthquake swarm intensified further and Galway's Wall continues to show signs of weakness. 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. The cracks in Chances Peak appear to be slightly larger. One of them can now be traced down the inside wall of the crater. There were also a number of small landslides on the Galway's Wall, both inside and outside. The wall appears to be becoming more unstable every day and catastrophic failure may be imminent.

Very little surface activity was seen on the dome today and there were very few rockfalls. Two small dome rockfalls were observed, one of which appeared to have been triggered by a large VT earthquake. Both generated small ash clouds. In addition, there was a rockfall from the northern flank of the dome, an area previously stable.

The VT earthquake swarm which started on 30 November has intensified. 239 VT events were recorded today compared to 165 yesterday. The increase has been gradual throughout this reporting period. All the events were located at shallow depths beneath the crater. The size of the larger events also increased noticeably. Four rockfall signals triggered the seismic network today, all from landslides on the Galway's Wall. Some of these appeared to be triggered by large VTs, one of which was felt at the Galway's Wall observation post.

Attempts were made to measure lines to the EDM reflectors on Chances Peak and Galway's Wall first thing this morning. The line from O'Garra's to Chances Peak showed no movement above the error of the technique overnight. The reflectors on the Galway's Wall could not be measured due probably to atmospheric conditions; attempts are currently being made measure them again.

A dome survey was carried out today; this should enable estimates to be made of the dome growth rate, which appears to have slowed over the past few days.

The sirens will be tested between 3 and 6 pm tomorrow.

Dr Barry Voight and Prof Steve Sparks will give a public lecture on the volcano at the Pelican Room, Vue Pointe Hotel on Thursday December 5, at 7:30 pm.

Montserrat Volcano Observatory