Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 9 December
to 16:00 10 December 1996
The current alert level is ORANGE

The volcano remains very dangerous, with the continuation of the volcano-tectonic earthquake swarm that began yesterday. Galway's Wall has become increasingly unstable, with large blocks of rock falling from it and more cracks appearing. The wall could collapse at any time, and trigger a lateral blast. The areas designated as zone A/B in the temporary risk map are extremely dangerous, as a lateral blast may cause pyroclastic flows and surges in any direction. In the very worst case, such surges could affect the top of St Georges Hill, and that area, or any other part of zone C/D, should not be occupied at night. Residents of zone E must remain alert, as the conditions could change suddenly and require the evacuation of zone E. At this time, the scientists are confident that zone E remains safe.

A total of 210 VT earthquakes were recorded during the last 24 hours. This swarm has now reached the same intensity as the previous swarm. The largest earthquakes today were about the same size as the largest earthquakes in the previous swarm. Last night a few larger earthquakes occurred, the largest in the current period of activity. All the earthquakes were located at shallow depths beneath the crater.

Eight landslides from the Galways Wall were detected by the seismic network during the last 24 hours. This is an increase since yesterday, and indicates that the wall becomes increasingly unstable during intense earthquake activity.

Helicopter inspections were made of the Galway's Wall this morning and afternoon. There were more landslides from the middle section of the wall overnight, and large blocks have fallen from the top of the wall towards the dome. Cracks along the wall are now about 20 m (60 ft) deep. There are also cracks across the top of the wall, making it very unstable.

Some views of the dome were possible today, and no changes were seen.

EDM measurements were attempted on the eastern triangle late this afternoon when the weather conditions cleared briefly. Unfortunately only a few measurements were possible, as the cloud level fell again.

Work has continued on installing a CCTV camera at the Galway's observation point. Hopefully this work will be completed tomorrow, and the pictures will be transmitted to the Observatory, allowing us to view the wall continuously during day light hours.

Montserrat Volcano Observatory