Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 09 March
to 16:00 10 March 1997
The current alert level is AMBER

The level of activity at the volcano has been slightly higher during the last 24 hours, with the recurrence of a volcano-tectonic and hybrid earthquake swarm. There were also a few small rockfall signals recorded throughout the day.

The seismicity today was higher than in previous days with a return to swarm activity. During the earthquake swarm, which lasted from 7.30 pm last night to 9.00 am this morning, 98 volcano-tectonic and 98 hybrid earthquakes were recorded. The volcano-tectonic earthquakes were located at shallow depths beneath the crater. There were also 7 rockfall signals, and significantly none of these rockfalls occurred during the earthquake swarm. Low level tremor has also been recorded at Gages seismic station at several times during the day.

Intermittent good views of the crater area were obtained today from Whites, Hermitage and Harris. There was continuous small-scale rockfall activity from the eastern face giving almost continuous light ash production, but in general the dome was quiet. The dome appeared very similar to previous days with only minor changes to the surface, but it does continue to grow slowly.

A long occupation GPS experiment is currently being run to a site at Hermitage. Results from yesterday's experiment confirmed that a baseline between Harris and the crater wall above Farrells shortened by 6.5 cm between 18 th January and 3 rd March. Re-measurement of the baseline yesterday did not show any further shortening.

The MiniCOSPEC was used to measure sulphur dioxide flux to the west of the volcano this afternoon. The results are currently being processed.

During the last few days the eastern slope of the dome has become more unstable. Given that the dome is now large and continuing to grow, 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 dramatically 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