Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 24 March
to 16:00 25 March 1997
The current alert level is AMBER

The level of activity at the volcano has remained low over the last 24 hours. The southern part of the dome is active, and rockfalls continue to dominate the seismic record.

Visual observations were made today during a helicopter trip to Galway's Mountain. The upper section of the southern face of the dome is active, and producing small rockfalls. The top of this face has some large extruded blocks. The September explosion scar in this area is nearly filled. So far, the scar has prevented fresh, hot material from falling over the top of the Galway's Wall, but soon there will be no barriers to prevent this from happening.

Fresh cracks have been observed on the eastern shoulder of Galway's Mountain, which lies at the eastern end of the Galway's Wall, in the last two weeks. This morning, a field party visited this are by helicopter, and made measurements of the size of the cracks. The cracks will be monitored to see if they are opening further.

There have been only 4 volcano-tectonic, 7 hybrid and 4 long-period earthquakes during the 24 hour period. There were 28 rockfall signals, a slight increase since yesterday.

The long-occupation GPS experiment continued today, with the GPS equipment being moved from Farrells to Hermitage. The data collected overnight show that the Farrells rim point has moved by 3 cm to the north-west since it was last measured on 8 March. There has been a total of 17 cm movement since this point was first measured on 18 January.

EDM measurements were made on the northern triangle. The final results are not ready yet, but the initial indications are that no movement has occurred in recent weeks.

Fresh growth at the summit of the dome has been observed in the last few days. The dome is now very big, and a dome collapse with large 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