Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 01 August
to 7 am 02 August 1997

Activity at the volcano overnight has remained at an elevated level with moderate to large rockfalls and pyroclastic flows being recorded for most of the period. Two hybrid swarms and one period of heightened pyroclastic flow activity have also occurred.

Yesterday evening, a hybrid earthquake swarm began at 16:17 and ended at 18:04 and consisted of 16 events. This was followed by a period of high amplitude tremor and pyroclastic flow activity from about 18:44 until 20:00. At this time glowing from behind St. George's Hill was seen periodically. This was most likely due to pyroclastic flows in the Gages valley.

A further hybrid earthquake swarm with about one event per minute began at 4:42 today and is still continuing at the time of reporting. This is a more intense swarm than the previous swarms this week and contains some very large hybrid events. It is expected that pyroclastic flow activity will soon follow on from this swarm. Although the most likely pathway for these flows will be the Gages valley towards Plymouth, pyroclastic flows could occur in any direction. The Gages valley is now filled up and flows and surges will overspill the valley anywhere along its length, and under no circumstances should people be in this area.

The activity is following a cyclical pattern in the tiltmeter with regular inflation and deflation of the volcano corresponding to the earthquake swarms and continuous pyroclastic flows respectively. However, pyroclastic flows have also occurred outside the most probable time period, and so at no time is it safe to enter the exclusion zone, including the Belham river valley.

A small mudflow signal also occurred last night at about 1:10. This emphasises that there is still a potential hazard from re-mobilisation of fresh pyroclastic flows deposits by heavy rain and all ghauts on the flanks of the volcano could be affected.

The new ash is still in the air in the west of Montserrat and therefore dust masks should always be worn in these areas. Drivers should also be considerate whilst driving in ashy conditions. The Belham River valley is very dangerous and should not be entered. Access to the exclusion zone is completely restricted, and people should stay completely away from the flanks of the volcano. Everyone should continue to stay alert, and listen to Radio Montserrat for any announcements.

Montserrat Volcano Observatory