Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 05 April
to 16:00 06 April 1997
The current alert level is ORANGE

The level of volcanic activity has been quite low today. However there are concerning signs that a major collapse of the south part of the dome may be imminent.

The volcano has been almost entirely cloud-free all day, allowing excellent views of the dome from the helicopter. A survey of the dome was undertaken this morning, and the results are now being processed. The southern peak of the dome has moved downwards in the last few days, towards the Galway's Wall. A large section of the dome has dropped by 20 metres in height, and moved about 25 metres to the south. A horseshoe-shaped depression now separates this active and unstable section of the dome from the rest of the main mass of the dome. If this movement continues, there may be a large collapse which would send pyroclastic flows down the White River valley. The scar in the dome and the notch in the Galway's Wall which were formed during the recent pyroclastic flow activity have been partially filled by talus material from further small collapses of the dome and by the outward and downward movement of the active dome. Vigorous steaming was observed from the back of the scar, and from the northern side of the dome.

The level of seismic activity has been low, with 16 volcano-tectonic earthquakes. There were no long-period earthquakes. Five of the volcano-tectonic earthquakes were large enough to be located and occurred below the crater between depths of 2 and 4 km. There has been a continuation of rockfall and pyroclastic flow activity, at the same level as during the last two days, with 27 signals recorded by the seismic network.

The cracks on Chances Peak and Galway's Mountain were measured this morning. There was no change to the cracks on Galway's Mountain. The crack on Chances Peak has not opened further, but continues to shear at about the same rate as before.

A long-occupation GPS survey between Harris and the crater rim at Farrells was started today. The instruments will be retrieved tomorrow.

COSPEC measurements were attempted this morning, but the wind was blowing from the north and so no measurements of the gas plume were possible.

Observations of the dome made today suggest that major pyroclastic flows to the south could occur at any time and MVO urges everybody to stay alert. Nobody should sleep in zones A to D tonight, which includes Plymouth, St Patrick's, the central corridor, Harris', Long Ground, Spanish Point and Richmond Hill. Zone E, which includes Corkhill and the airport, remains safe at this time.

Montserrat Volcano Observatory