Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 21 October
to 16:00 22 October 1996
The current alert level is AMBER

The level of volcanic activity has increased slightly since yesterday. The seismicity has been dominated by rockfalls from the growing dome, which have produced small ash clouds.

There were twelve rockfalls signals today. The largest signals were at 21:00 last night and 12:39 today. Both events probably resulted in small ash clouds. Ash was seen from the second event, and it drifted to the west. Light ashfall was also noted in Plymouth this morning.

Only four volcano-tectonic earthquakes were recorded, a sharp decrease in numbers since yesterday. Two of these were at a depth of about 2 km beneath St Georges Hill, and one was at a depth of 5 km to the north of the crater. The fourth earthquake was too small to locate. There was only one small long-period earthquake.

Observations of the volcano have been possible from Whites and the helicopter today. The height of the October 1 dome has increased from 808 metres (2640 ft) to 829 metres (2710 ft) since 18 October, an increase of 70 ft. Several rockfalls were observed on the eastern face, and the dome appeared to be more active than in recent days. Some material was also falling from the northern side of the scar. Vigorous steaming occurred from the south of the October 1 dome.

No COSPEC measurements were carried out today. The results of yesterday's measurements gave an average sulphur dioxide flux of 580 tonnes per day. This is lower than the measurement made on 17 October.

EDM measurements were carried out on the eastern and western triangles today. The western triangle measures lines between Amersham and Chance Steps, while the eastern triangle is between Castle Peak, Long Ground and Whites. The results are being processed just now, and will be reported tomorrow. GPS measurements were made on the network that straddles the volcano. This network was last measured on 12 October. The results are currently being processed.

The volcano remains in an active and highly dangerous state. Further activity, possibly leading to an explosive event could occur with little warning in the near future. 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.

Montserrat Volcano Observatory