Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 28 February
to 16:00 01 March 1997
The current alert level is AMBER

Activity at the volcano has continued at about the level during the last 24 hours, with another earthquake swarm being recorded. Very good views of the dome today allowed observation of continued growth of a new lobe on top of the January dome. A few small rockfalls were also observed from the Galways wall.

A swarm of volcano-tectonic and hybrid earthquakes began at 1:56 am this morning and continued to the end of the reporting period. The most intense period of activity was between 2:00 and 8:00 am this morning. A total of 99 volcano-tectonic earthquakes and 42 hybrid events were recorded, most of these during the swarm. Eleven rockfalls were also recorded during the reporting period. Most of these produced only small ash clouds which drifted to the west of the volcano depositing ash on Chances Peak and surrounding areas. There were no long period events.

Despite intermittent heavy downpours of rain, the summit of the volcano was clearly visible for most of the day. Extrusive growth is still confined to the January scar in the south east of the dome. A new lobe which was first observed in this area yesterday, has continued to grow up and out to the east. A small portion of the October 1 dome, located just north of the January scar has inflated by about 10 metres over the past few days. Rockfalls continue to occur mainly from the active south-eastern area. Some rock avalanches involving both hot and cold material were also observed from northern parts of the dome behind the Farrells wall. Several small rockfalls were observed on the Galways wall with the newly operational CCTV camera located at the Galways observational post.

A dome volume survey using the range finding binoculars and GPS equipment was conducted early this morning. The results of this survey is not yet available and would be given in a later report. Measurements to the top of the dome were made with a theodolite from Whites and Harris today. These indicate that the highest point on the dome is now about 942 metres above sea level.

The second of two cracks which are usually monitored at the top of Chances Peak were remeasured today. Measurements across this crack show continued slow opening with the total opening now 10 cm. Movement of material along the crack is now the greatest component of the total movement on this crack. This shear motion has increased by 8 cm since the last measurement were made on 11 February. This gives a total movement in this direction of 16 cm since 4 December.

The volcano remains active and potentially dangerous. The dome is currently larger than ever before, and shows signs of becoming more active. The situation could worsen over a period of a few hours, and so it is dangerous to spend the night in the evacuated areas. People entering Zone C are reminded to remain alert at all times, and spend the minimum possible time in the evacuated zone. Residents should be reminded that at this current level of alert persons should not be permanently residing in Zones A, B or C. The ash levels in Plymouth can be hazardous, and so it is essential to wear a mask when there is ash in the air. The Tar River Valley and the upper Galway's area are very dangerous and should not be entered at any time.

Montserrat Volcano Observatory