Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 11 March
to 16:00 12 March 1997
The current alert level is AMBER

Activity at the volcano has been quieter than yesterday but dome growth continues with associated rock avalanches into the Tar River valley. Poor visibility for most of the day did not allow any good views of the summit area.

Seismic activity at the volcano has been relatively quiet since the end of the last earthquake swarm at 14:16 pm yesterday. Activity since this time has been dominated by rockfall signals with another volcano-tectonic earthquake swarm beginning at 14:58 pm today and continuing past the end of the reporting period. A total of 12 hybrids, 6 volcano-tectonic events, 7 rockfalls and 1 long-period earthquake were recorded during the period. Low amplitude tremor was also recorded on the Gages seismic station for most of the night,

Low cloud cover prevented any clear views of the crater area today. Views of the lower flanks of the dome from the eastern side of the volcano indicate that rockfall activity continue to be concentrated in a wide area extending from the south-eastern to the north-eastern part of the dome. The CCTV located at the observation post at Galway's has allowed good views of rockfall activity in this area. This has enabled a direct correlation between volcano-tectonic earthquakes and rock avalanches from the Galway's wall.

Another long occupation GPS experiment between Harris Lookout and Hermitage was carried out during the past 24 hours. This is intended to verify the results obtained in the measurements carried out during the period March 10-11th. The results from this latest occupation is not yet available.

EDM measurements were made today on the radial lines between Upper and Lower Amersham and Lower Amersham and Chances Peak steps. The results of these measurement are not yet available and would be given in a later report.

During the last few days the eastern slope of the dome has become increasingly 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 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