Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 21 March
to 16:00 22 March 1997
The current alert level is AMBER

The level of activity at the volcano has been at the same elevated level as yesterday. Activity up to midday was dominated by rockfall and small pyroclastic flow signals. Following this a swarm of VT and hybrid earthquakes have become the main source of seismic signals.

The current hybrid and volcano-tectonic earthquake swarm began at 12:09 pm this afternoon and is continuing. So far 33 hybrid earthquakes and 6 volcano-tectonic earthquakes have been recorded. As in previous swarms, there has been further small pyroclastic flows over the Galway's Wall associated with large hybrid earthquakes. One such event just outside the reporting period produced an ash column to a height of about 5000 feet. This was blown to the north-east by the wind. In total 23 rockfall and pyroclastic flow signals have been recorded during the reporting period. Two (2) long period events have been recorded today. Continuous low amplitude tremor on the Gages seismometer began at about 3:00 pm this afternoon and is continuing

Visual observations from the eastern side of the volcano suggest that growth is continuing in the uppermost parts of the dome. Rockfalls and small pyroclastic flows were observed during the day originating from this area. Observers at Harris Lookout last night took advantage of the very clear condition. Incandescence was most pronounced from the upper most areas of the January dome with lesser amounts present on the October dome.

A COSPEC run was started this morning but unfortunately had to be abandoned due to unfavourable wind conditions.

No EDM or GPS surveys have been done today. Processing of the data collected during the fan survey yesterday has begun. The results will be available in a future report.

The dome is now continuing to grow freely in the summit region. The dome is now very large, and a large collapse and pyroclastic flows could happen with little warning. It is dangerous to spend the night in evacuated areas, because the situation could worsen rapidly over a period of a few hours. The night-time visits by scientific teams into zones B and C are part of the routine monitoring and should not be taken as an indication that it is safe to spend the night in such areas. 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. People visiting the north-eastern flanks in zone C should remain attentive while there is increased activity of the dome in the north adjacent to the Farrells wall.

Dr Angus Miller returned to MVO today after a brief but well deserved holiday. Mr Richard Luckett (Team Seismic) left the island today after a 2 month tour of duty at MVO.

Montserrat Volcano Observatory