Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 7 June
to 4 pm 8 June 1997
The current alert level is ORANGE

Pyroclastic flow activity has continued during the last 24 hours, with small pyroclastic flows in the Tar River valley and Tuitt's Ghaut. Excellent views of the dome were possible this afternoon.

The level of pyroclastic flows was about the same today as yesterday, with peaks in activity between 4 pm and 8 pm last night and 8 am and 12 pm this morning. During the peaks in the activity, small pyroclastic flows and rockfalls were observed regularly on a wide sector of the dome, from the south-east round to the northern slopes. Most of the pyroclastic flows were in the Tar River valley, and a few ran down the upper reaches of Tuitt's Ghaut. There were also a few small rockfalls at the top of Mosquito Ghaut. Many of the pyroclastic flows were preceded by falling and bouncing boulders, which could be seen clearly and even heard from several kilometers away.

The volcano was clear of cloud for most of the afternoon, so that measurements and observations of the dome could be made from Windy Hill, Harris, Whites and the airport. At the top of the dome several solid slabs of lava have been extruded in the north-easterly direction. The northern and eastern slopes of the dome are smooth. The notch at the top of Tuitt's Ghaut has been filled with debris from the dome, and there is a lot of material in the upper reaches of the ghaut.

Seismic activity at the volcano has increased over the last few days, with a slight increase in the number of long-period and hybrid earthquakes. There were 17 small hybrid earthquakes and 23 long-period earthquakes in the last few days. Over half of these earthquakes triggered rockfalls from the dome. There were 112 rockfall signals, an increase since yesterday because there were two periods of increased rockfall activity during this reporting period.

No COSPEC measurements were made today because the plume was quite diffuse. The measurements made over the last few days gave values of between 500 to 600 tonnes per day of sulphur dioxide flux. These values are higher than normal, and indicate that the volcano is in an active state.

A visit was made to Chances Peak to install new EDM reflectors. The distance between these reflectors and the observation post at Galway's will be measured. The first measurements were made successfully this afternoon. The cracks on Chances Peak were also surveyed during the visit, and showed continued movement at about the same rate as when they were last measured 4 days ago.

Further pyroclastic flows are expected, and they could easily extend down Tuitt's Ghaut beyond Bramble village. The revised zones A and B on the risk map should not be visited. These areas include Bramble, Bethel, Harris Paradise, Spanish Point, Farms, Trants, Riley's, Streatham, and Farrell's.. WH Bramble airport remains operational for the time being, although the public are reminded it is open for essential travel purposes only: people not travelling should not visit the airport.

Montserrat Volcano Observatory