Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 1 January
to 16:00 2 January 1997
The current alert level is ORANGE

Activity during this reporting period has been dominated by rockfalls and small pyroclastic flows from the October 1 dome as it continues to grow. The activity could escalate at any time with little warning. Large pyroclastic flows into the Tar River Valley area are most likely but a sudden collapse of the Galway's Wall is still a possibility. Either of these could uncover fresh lava in the dome which might then lead to a lateral blast or a vertical eruption. These could have serious consequences for much of the evacuated area. There is no access to zone A/B. Restricted access is allowed to zone C/D but only for essential purposes and by people who can leave rapidly. There is normal occupation of all other zones.

Visibility has been moderate for much of today. Rockfalls and small pyroclastic flows have continued from the October 1 dome, mainly down its eastern face in the area close to Castle Peak. The rockfall activity has been at a relatively high level all through the reporting period and the longest flows have reached beyond the Tar River Soufriere. Many of the rockfalls and flows generated ash clouds which drifted to the west and south west forming a semi-continuous ash plume which could be tracked at a height of about 4,000 ft over 60 miles westwards from Montserrat.

A total of 62 rockfalls triggered the seismic network and many other smaller ones were recorded throughout the day. In addition to rockfalls, 1 volcano-tectonic earthquake and 36 hybrid events were recorded. The banded seismic tremor which had been recorded over the past few days died out overnight.

COSPEC measurements were made today of the level of sulphur dioxide in the gas plume. The average value was about 300 tonnes per day, similar to recent results.

EDM measurements to the reflector on Castle Peak were attempted. These were unsuccessful, probably due to ash deposits on the reflector.

Gravity and GPS measurements were made today along a radial line to the north of the volcano.

Montserrat Volcano Observatory