Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 10 May
to 16:00 11 May 1996

The activity at the Soufriere Hills Volcano during this period has been at a slightly higher level than that observed during the previous 24 hours, although overall it is still relatively low. Seismicity continues to be dominated by small- to moderate-sized rockfalls. Many of these rockfalls generated small ash clouds which were blown on the wind towards the west and some of them were associated with very small pyroclastic flows in the Upper Tar River Valley area. Several of the ash clouds resulted in small quantities of ash being deposited in the Upper Gages, Amersham and Fort Barrington areas. A few small long period events were also recorded. Intermittent low amplitude broadband tremor was recorded at the seismic stations closest to the volcano. Two small volcano-tectonic earthquakes were located: one at a depth of less than one km beneath the crater and the other at a depth of 2.5 km beneath St. George's Hill.

The Eastern EDM triangle was measured today and the results show a small shortening of 3 mm for the lines to Castle Peak compared to yesterday's values. The University of Puerto Rico GPS network was also reoccupied but the data is still being processed.

Visual observations of the crater area were attempted from various ground points and the helicopter although visibility during most of the day was variable. A small pyroclastic flow which had travelled about 300 m from the base of the Old Castle Peak dome into the Upper Tar River Valley area, just south of the area scorched by the flows of early April, had set fire to some trees. Rockfalls were concentrated on the eastern flank of the dome. No significant changes were noticed in the areas of the moat beneath the Gages and Farrell's walls. Steam emissions were seen from several areas of the dome, with the most active region being the southwestern moat.

Chandradath Ramsingh of the Seismic Research Unit returned to Trinidad yesterday after a month's tour of duty at the MVO.

The present level of activity at the Soufriere Hills Volcano continues to cause concern to the scientists. The MVO urges 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.

Montserrat Volcano Observatory