Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 7 September
to 8 am 8 September 1997

There have been two episodes of pyroclastic activity during this reporting period. The first occurred late yesterday afternoon (between 4:10 and 7:00 pm) and shed material down the area of Mosquito Ghaut and Farrell's as far as Harris. The strong wind carried ash north-eastwards at a height of 4 to 6,000 feet. Material was not confined to the valley and new material was deposited over much of the Farrell's Plain.

The second period of pyroclastic flow activity was between 6:00 to 7:45 am this morning. This episode was preceded by a swarm of hybrid earthquakes between 1:00 and 3:00 am comprising about 50 events. Pyroclastic flows again descended the Farrell's Plain and towards the end of the episode entered into Unnamed Ghaut and then into the upper part of the Belham River valley. The peak of this activity was at a higher level than during yesterday evening although it did not continue for as long. Ash was again blown north-eastwards and did not get above 10,000 feet.

The start of collapses from the dome has been expected for some time. The size of individual collapses is impossible to predict, but they are likely to be larger than the two during the past 16 hours. The re-start of hybrid earthquakes prior to collapses is of additional concern as they indicate pressurisation of the dome.

Pyroclastic flows can now get into the Belham Valley freely and the next collapse may send pyroclastic flows to the Belham Bridge and beyond. Flows could thus impact upon Old Towne and Friths areas and associated surges could get to Salem. With pressurisation of the dome and collapses, the possibilities of explosive events is increased. None of the areas in the exclusion zone should be occupied at this time and all residents and businesses south of the Nantes River are urged to move out immediately. All residents of Montserrat should be vigilant and listen to Radio Montserrat for further information.

Montserrat Volcano Observatory