Montserrat Volcano Observatory

Daily Report
Report for the period 16.00 30 May
to 16:00 31 May 1997
The current alert level is ORANGE

The level of activity has remained quite low today but regular rockfalls and small pyroclastic flows indicate that the dome is still growing. Observations today show that it is particularly active in the summit region and on the northern to south-eastern flanks.

The volcano has been covered by thin cloud for most of the day but good views were obtained this morning of the northern and eastern flanks of the dome. A survey of the northern and north-eastern flanks of the dome was completed from two new observation points using the laser binoculars. The two new observation points have also been surveyed today using GPS techniques.

Observations suggest that the dome is growing in the summit area and on the upper northern and eastern flanks. The northern flanks in particular are steep and noticeably blocky. Spiny structures, a conical 'peak' and a ridge with a smooth arcuate NW side have grown on the upper northern flanks of the dome. Regular small rockfalls were generated in this northern summit area during the morning.

On the north eastern flanks of the dome the channels and chutes which were developed in the middle of May are now covered by an extensive talus slope. There were regular small rockfalls down this slope during the morning. The eastern flanks of the dome are very blocky and small changes in the structure have been noticed from the summit area down to the lower parts of the dome.

Small pyroclastic flows generated during the morning mostly travelled down the south eastern flanks of the dome, nevertheless a small pyroclastic flow was reported at 5.15pm entering Tuitt's Ghaut.

The seismic activity during the last 24 hours has been similar to the last few days, with 80 rockfall signals and 11 hybrid earthquakes. There were also 6 long-period earthquakes most of which triggered rockfalls.

Further COSPEC runs were made today at sea using the Police launch. The results will be processed this evening.

Observations today indicate that the dome is still growing and is very active at the summit and in a broad sector which includes the upper northern to south eastern flanks. Further dome growth will continue to steepen and destabilise the existing structure. Pyroclastic flows generated on the northern side of the dome may enter the northern Ghauts on a more regular basis during the next few days. Only essential visits should be made to the central corridor and it should not be used as a route to the airport. Large pyroclastic flows could occur with no warning in the Tar River and White River valleys. Nobody should enter zones A and B, and only essential visits should be made to the evacuated zone. Ash masks should be worn when in the ashy areas.

Montserrat Volcano Observatory