Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 10 October
to 16:00 11 October 1996
The current alert level is AMBER

Despite generally poor visibility, continued rockfall activity at the October 1 dome suggest that the dome growth continues. Seismic activity remains low and is still dominated by rockfall signals.

Six small rockfall events were recorded by the seismic network today; a slight reduction n numbers compared to yesterday. The increase in occurrence of large long period earthquakes noted yesterday has subsided and only one long period event was recorded today. One regional event and one hybrid earthquake was also recorded during the period. The regional event occurred at 05:27 early this morning. A single volcano-tectonic event which was located just south of Bethel at a depth of 1.55 kmwas also recorded today. Intermittent broadband tremor on the Gages seismic station, was recorded throughout the period with an increase in amplitude from 02:20 to 05:48 on 11 October.

Visibility was poor for most of the day since low cloud cover only allowed views of the lower flank of the volcano. Observations from Whites very early today revealed that there were regular small cascades of incandescent material from both shoulders of the eastern face of the dome. Occasional slippage of material also occurred from a central gully which has developed on the eastern side of the dome. Some rockfalls were observed during the day from the coastline at the mouth of the Tar River. Rockfall activity during the past two days have been quite frequent but have often been too small to be recorded by seismic stations closest to the volcano.

Very choppy conditions prevented an attempt to conduct a bathymetric survey of the sea in the area of the new delta today. This exercise, when completed, would allow a more accurate estimate to be made of the volume of material erupted by the volcano during the course of the eruption.

No EDM or GPS measurements were made today.

Calibration of all the recently installed broadband seismic stations began today and should be completed by tomorrow.

Mr Desmond Seupersad of the Seismic Research Unit left Montserrat today after another 4 week tour of duty.

The continued rapid growth of the October 1 dome means that large rockfalls and possibly pyroclastic flows may occur during the next few days. The volcano remains highly active, and pyroclastic flows could trigger another explosive eruption with very little warning. Everyone who enters the evacuated zone must remain alert and be ready to move at short notice. Individuals who go beyond the Long Ground area into the Tar River valley are risking death. All residents of Montserrat are urged to become familiar with the new alert system and evacuation procedures which was published in the newspaper today.

Montserrat Volcano Observatory