Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 12 June
to 4 pm 13 June 1997
The current alert level is ORANGE

Pyroclastic flow activity continues, with the pulse of activity this morning being more intense than previous episodes. Most of the pyroclastic flows were in the Tar River valley, although low cloud prevented detailed views.

There was a prolonged period of pyroclastic flows between 8 am and 10 am today, and the intensity of the activity was the highest seen in the last week. Visibility was poor, and most of the flows could not be seen from the airport. The activity was concentrated in the Tar River valley, with only a few small rockfalls observed in the upper part of Tuitt's Ghaut. Observations were made from Harris just after the peak in activity, and a lot more dome talus was noted in the upper part of the ghaut, which has been deposited in the last few days. The volcano has been quiet since noon.

The number of long-period earthquakes increased from 12 yesterday to 27 today, which is the highest number of long-periods seen since the middle of May. Otherwise, the seismic activity was similar, with 4 small hybrid earthquakes and 122 rockfall signals.

The volume of the lava dome on 30 May was about 65 million cubic metres, according to measurements made from photographs. This represents an increase in volume of about 4 million cubic metres between 19 and 30 May, a rate of over 4 cubic metres per second. This high rate indicates that dome growth was very active during that time, and it is likely that growth has continued at a similar rate in the last two weeks.

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.

Montserrat Volcano Observatory