Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 14 October
to 16:00 15 October 1996
The current alert level is AMBER

Activity at the volcano increased slightly today, and three large long-period earthquakes were recorded. The largest earthquake at midday was accompanied by a small ash cloud. Views of the crater area have been restricted by low cloud.

The seismicity has been dominated by three large long-period earthquakes which were recorded at 04:11, 12:00 and 14:29. The largest of these occurred at 12:00 and was accompnied by a dark-brown ash cloud which rose about 2000 ft above the volcano, and was blown to the west. These earthquakes are thought to be due to small explosions within the dome.

Five volcano-tectonic earthquakes and a moderate rockfall signal were also recorded. Four of the VT earthquakes were located close to the crater, at depths of about 2 km. A slightly deeper earthquake, with depth of 5.5 km was located near Roches Mountain.

Visibility has been poor today, but some views of the October 1 dome were obtained from Whites this morning. A new spine was noted on the northern side of the dome, and several small rockfalls were seen on the eastern face.

EDM measurements were made today from Whites to Castle Peak, but the results are not yet available. Processing of the GPS data collected during the last few days is still continuing, and the results should be available tomorrow.

More measurements of sulphur dioxide gas were made today with the COSPEC instrument. The measurements made on Sunday show sulphur dioxide emissions of about 550 tonnes, which is similar to the measurements made several weeks ago.

Richie Robertson left Montserrat today for a short trip to Trinidad. In his absence, Willy Aspinall is acting head of the Observatory.

The small ash cloud and the long-period earthquakes that occurred today indicate that the volcano remains in an active and highly dangerous state. Further activity, possibly leading to an explosive eruption, could occur with 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.

Montserrat Volcano Observatory