Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 23 March
to 16:00 24 March 1997
The current alert level is AMBER

The level of activity at the volcano has been low over the last 24 hours. Rockfalls are the predominant phenomena observed in the field and recorded by the seismic network.

There have been a total of only 2 volcano-tectonic and 3 hybrid earthquakes in the current period. 20 rockfall signals were recorded, which is about the same number as yesterday. There have also been 11 long-period earthquakes. These long-period earthquakes are small, but the number of events has been increasing in the last few days.

Visual observations were made from the helicopter yesterday evening and this morning. At dusk yesterday, the southern side of the dome was very active. In particular, there was incandescence from the summit of the January dome right down to the talus, and there was some glowing of the pre-September, 1996 material. Two early flights this morning confirmed that the southern face of the dome above Galway's Wall is very active, with a substantial amount of new debris shed from the active area. A few rockfalls were seen today.

A long occupation GPS experiment was started today from Harris Lookout to Farrell's crater wall. This will be completed tomorrow.

Nine COSPEC runs were completed today along the road to the west of the volcano. The data will be analysed tomorrow and published in a later report.

Results from the survey of the pyroclastic fan completed on Friday show that the current total volume of the delta, above and below sea level, is 15.5 million cubic metres, which is about one third of the current size of the dome.

The width of one of the cracks on Chances Peak was measured today. This has shown some opening of the crack over the last couple of months. Today's measurements showed that the side of the crack furthest away from Chances Peak had sheared south-westwards by 3.4 cm, but had not opened significantly since it was last measured on 8 March.

Fresh growth at the summit of the dome has been observed in the last few days. 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. 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