Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 23 June
to 4 pm 24 June 1997
The current alert level is ORANGE

The activity over the last 24 hours has been dominated by swarms of hybrid earthquakes, and by occasional strong steam venting, and by a few very small rockfalls and pyroclastic flows

A swarm of hybrid earthquakes, which started just before 4pm yesterday afternoon, reached its peak between 5pm and 6pm, and declined to background level by 10pm last night. Another swarm of frequent hybrids developed about 4.30am this morning, and lasted until nearly midday. There have been a total of 482 hybrid earthquakes during the reporting period. There were also 2 long-period events, 80 rockfall signals, but no volcano-tectonic earthquakes,.

The dome cleared very briefly for a few minutes at 6:15 am this morning and observations made during this clear spell indicate that it was similar in appearance to yesterday with a blocky appearance and small spines in the summit area. A distinct change since yesterday was the occurrence of a number of small pyroclastic flows down Mosquito Ghaut which travelled up to 1km from the northern crater rim. This is the first time since the 17 June that pyroclastic flows have occurred in Mosquito Ghaut indicating that the potential for large pyroclastic flows down the northern Ghauts has not diminished. Observations today also showed that some rockfall activity has occurred on the east and north east side of the dome with one or two small pyroclastic flows travelling into the Tar River valley.

Data from the Chance's Peak tiltmeter shows that the pattern of alternating periods of inflation and deflation of the volcano continues, although these are now less uniform than they were in previous days.

More COSPEC runs were made today - results are being processed.

Further pyroclastic flows could travel into Gages valley, Mosquito Ghaut, Tuitt's Ghaut or the Tar River valley at any time. Access to Plymouth remains restricted. Zones A and B which include Tuitt's, Bramble, Bethel, Spanish Point, Farms, Harris and Trants, are extremely dangerous and nobody should go into this area.

Bramble Airport is operational, but the public are reminded that it is open only for essential travel purposes.

Montserrat Volcano Observatory