Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 11 June
to 4 pm 12 June 1997
The current alert level is ORANGE

The volcanic activity at the Soufriere Hills volcano continues to follow the same pattern of the last several days, with small rockfalls and pyroclastic flows in Tuitt's Ghaut and Tar River valley. The activity is still periodic, and repeats every 16 hours or so. Over this twenty-four hour period, the intensity of the pulses has decreased slightly.

One pulse of activity commenced about 5.30 pm yesterday afternoon and died down about 1 am, and the second got going about10 am this morning, and was continuing at the end of this report. The observer at the airport reported that only a few small rockfalls were visible today, with the activity divided between Tar River and Tuitt's Ghaut.

Seismic activity at the volcano has remained at about the same level, with 22 hybrid and 12 long-period earthquakes. About half of these earthquakes triggered rockfalls, and there were a total of 123 rockfall signals. There was one volcano-tectonic earthquake which was too small to locate.

A survey of the height of the dome, made on 8 June, showed that it had reached a height of 1010m asl (about 3315 feet), that is about 300 feet higher than Chance's Peak. Material has continued to accumulate on the upper parts of the northern and eastern sectors of the dome.

The results of eight sets of COSPEC runs made yesterday produced a range of estimates from 400 tonnes/day to over 1000 tonnes/day, with an average value near 800 tonnes/day. Further COSPEC measurements were made today, the results will be processed shortly.

An expedition was made to Chance's Peak today to retrieve an unserviceable tiltmeter and a defective accelerograph.

Further rockfalls and pyroclastic flows are expected, and could easily extend down Tuitt's Ghaut beyond Bramble village. Zones A and B on the risk map should not be visited. 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.

Mr Wilkie Balgobin from the SRU arrived yesterday to take up duties at the MVO.

Montserrat Volcano Observatory