Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 6 December
to 6 pm 7 December 1997

Seismicity has been at about the same level today, with mainly rockfall signals being recorded. Visibility has been good and reasonable views of the dome were achieved.

Between 16:00 yesterday and 16:00 today, the broadband seismic network recorded 121 rockfall signals, 46 long period and 17 hybrid earthquakes. This activity indicates that the dome is still growing.

Visibility was good today, and reasonable views of the dome were obtained from a helicopter flight this afternoon. Observations were also made from Jack Boy Hill and Old Towne. Photographs were taken from these locations and at Garibaldi Hill, and will be used to determine the current size of the dome. The active growth is still concentrated in the Galways area, but some small rockfalls were also observed into Tuitts Ghaut. Small continuous rockfalls from the western side of the talus slope above Galways appear to be eroding the side of Chances Peak. Diffuse ash clouds have been produced throughout the day from these rockfalls. The wind direction today was towards the north and north-west, and some areas of Woodlands experienced light ashfall overnight. However, measurements of the average dust levels over the last 24 hours in St. Johns, St. Peters and Woodlands were still low.

Electronic distance measurements were made today on the triangle between MVO south, Garibaldi Hill and Lees Yard. A GPS campaign was also completed on the stations at Old Towne, St. George's Hill, Waterworks and Lees Yard. The data are still being processed from both these sets of measurements.

Although activity is still mainly focused on the southern side of the volcano, past experience has shown that the area of growth on the dome can change very quickly and pyroclastic flows could occur down any of the ghauts around the volcano with little or no warning.

Dr. Willy Aspinall returned to Montserrat from Antigua today, and Dr. Simon Young and Mr. Gordon Woo also visited for a brief time this afternoon.

Montserrat Volcano Observatory