Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 22 March
to 16:00 23 March 1997
The current alert level is AMBER

The level of activity at the volcano has been slightly lower in the last 24 hours, with an earthquake swarm but fewer pyroclastic flows in the Galway's area.

The hybrid and volcano-tectonic earthquake swarm which began yesterday had died down by midnight, and finally ended at about 3:30 am. There were a total of 32 volcano-tectonic and 37 hybrid earthquakes in the period. The largest earthquakes in the swarm were of a similar size to those of the previous swarms. One strong earthquake at 4:06 pm caused a pyroclastic flow over the Galway's Wall, and an ash cloud to about 5,000 ft above sea level. There was a slightly larger earthquake at 7:57 pm, but no pyroclastic flow could be seen associated with this event. The VT earthquakes are not usually felt on Montserrat, and are small in comparison with tectonic earthquakes which occur in the Caribbean and around the world. However, the recent swarms have contained some earthquakes that are larger than any of the volcanic earthquakes recorded recently. These earthquakes suggest that the magma pressure may be high, and an intrusion may be occurring at shallow depths within the volcano.

A total of 18 rockfall signals were recorded, a slight decrease in numbers since yesterday. There have also been 12 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 eastern side of the volcano, but there have not been any major changes in the dome. The Galway's Wall area has been quiet today, with no pyroclastic flows observed since the cessation of the earthquake swarm.

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