Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 21 April
to 16:00 22 April 1996

The seismic activity at the Soufriere Hills Volcano has been dominated by rockfall signals during the last 24 hours. Moderate-sized rockfalls occurred at 21:47 and 22:26 last night, and 02:56 and 06:35 this morning. The repetitive hybrid earthquakes that have occurred since 09 April have continued, but the events are smaller and the rate has decreased to about one earthquake every three or four minutes.

EDM measurements were made on the eastern triangle of the EDM network. The results are still being processed. A total of nine lines to the north and east of the volcano were remeasured using the GPS equipment. The data collected will be processed overnight. The results are now available from repeated measurements of the same lines over the last week. It has been calculated that the precision in the line length measurements is better than one centimetre. So far, the line lengths have all changed by less than one centimetre, which is consistent with the volcano deforming only slowly.

Visual observations of the volcano have been restricted by low cloud. Several rockfalls were heard by scientists working in the east, and some of these produced small ash clouds that drifted west. This afternoon, a brief cloud clearance allowed observers at Harris' Lookout to see the present spine. The spine has fallen over, and is now lying at the top of an unstable slope. It is expected that the spine will collapse and fall down the slope soon.

The Soufriere Hills volcano still remains highly active and dangerous. The Montserrat Volcano Observatory continues to urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

Professor Steve Sparks and Dr Jenni Barclay joined the MVO staff over the weekend. They will be helping to estimate the volume of the dome and also assist with other aspects of the volcano monitoring over the next few weeks.

Montserrat Volcano Observatory