Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 9 January
to 16:00 10 January 1997
The current alert level is ORANGE

The October 1 dome has been active during this period, producing many rockfalls and pyroclastic flows. The level of activity has been slightly lower in the last 24 hours. However observations of the dome show that parts of the dome are very unstable, so further pyroclastic flows are expected in the next few days. A major collapse of the dome could result in another explosion, similar to the September 1996 event. At the moment, the scientists are confident that zone E, which includes Cork Hill and the airport, remains safe. However, the situation could change rapidly, and residents of Montserrat should remain alert and continue to listen to Radio Montserrat.

Visibility has been good today, and observations of the dome were made from Whites, Harris' and from the helicopter. Sometime during the last two days, at least one pyroclastic flow has reached the sea. The ongoing rockfall and pyroclastic flow activity has produced an ash plume at an altitude of about 4,000 feet, with occasional ash columns to about 6,000 feet. The ash has been blown over Plymouth There has been heavy erosion of the chute which runs through Castle Peak, and there is now a large unstable block in the middle of the chute. There appears to be new growth in the northwestern side of the October 1 dome. This growth is still contained with in the scar left by the September 1996 explosion, and so the new growth does not directly threaten the Gages Wall.

The seismic activity continues to be dominated by rockfalls and pyroclastic flows. A total of 103 rockfalls were recorded today, a decrease from the number recorded yesterday. Other seismic signals included 8 hybrid earthquakes, and three long-period events.

Sampling of airborne dust particles was carried out in Plymouth today. The samples collected will be sent to England for analysis. COSPEC measurements made today gave a result of 390 tonnes per day of sulphur dioxide, a decrease since yesterday.

Gravity and GPS measurements were made this afternoon along a line in the southwest of the volcano, from Chances Steps to the sea. This is a continuation of a line that was measured previously. EDM measurements were attempted from the reflector on Chances Peak, but could not be made due to the amount of ash in the atmosphere.

Montserrat Volcano Observatory