Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 13 March
to 16:00 14 March 1997
The current alert level is AMBER

Activity at the volcano has been slightly higher than yesterday with the occurrence of another shallow earthquake swarm. Several small pyroclastic flows travelled over Galway's Wall. The new spine, first seen on 11 March, shows little signs of any further growth.

Seismic activity at the volcano has been dominated by another swarm of volcano-tectonic and hybrid earthquakes. The swarm began at 2:24 am this morning and is continuing past the end of the current reporting period. A total of 136 hybrids and 33 volcano-tectonic events have been recorded so far. Rockfall activity has been slightly lower with only 3 events recorded. However 5 pyroclastic flows over the Galway's Wall. Some of these events continue to coincide with volcano-tectonic earthquakes. An isolated pyroclastic flow signal was also recorded at 3:54 am. It is thought that this originated from somewhere on the eastern side of the dome complex. Low amplitude tremor was also recorded on the Gages seismic station.

Visual observations have been hampered by low cloud around the volcano. However some brief views of the eastern side of the dome complex were had this morning. Minor rockfall activity was observed from Whites originating from several areas of the dome complex. The CCTV located at the observation post at Galway's has allowed good views of the pyroclastic flow activity in this area. The maximum run-out distance of these flows is of the order of 1km from the crater wall. The spine on the summit of the dome which was first seen 3 days ago has shown little further growth. Overall it appears that visible growth of the dome complex has slowed.

No GPS surveys were performed today.

EDM measurements on the northern triangle (Windy Hill-Farrell's-St. George's Hill) indicate that there has been no departure from the stable trend which has been maintained over the past year.

A COSPEC run was carried out this afternoon between Fox's Bay and Gingoes. The data is currently been processed and will be available for a future report.

During the last few days the eastern slope of the dome continues to be unstable. Given that the dome is now large and continuing to grow, albeit slowly at the moment, a large collapse and pyroclastic flows could happen with little warning. The increase in activity from the Galway's Wall makes this area particularly hazardous. It is dangerous to spend the night in evacuated areas, because the situation could worsen rapidly over a period of a few hours. People entering Zone C are reminded to remain alert at all times, and spend the minimum possible time in the evacuated zone. The Tar River Valley and the upper Galway's area are very dangerous and should not be entered at any time.

Montserrat Volcano Observatory