Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 21 September
to 7 am 22 September 1997

Activity at the volcano has been at a moderate level overnight. The seismic records have been dominated by hybrid earthquake events. There have been a variety of sizes of these events though generally they have been small. The number of events diminished from 4 pm until around midnight.

The main feature of the activity overnight was a pyroclastic flow which occurred just before 1am this morning. The relative sizes of the seismic signal at each station indicate that this flow went to the east of the volcano. An ash column developed rapidly and was blown to the north-west and east.

Following this event there was an hour of small to moderate rockfall activity and then a return to low intensity hybrid earthquake activity. Currently activity is at a relatively low background level

The probability of further large collapses and pyroclastic flows is high. Large pyroclatic flows could travel down the Belham Valley as far as the sea. Residents of the exclusion zone south of Nantes River are thus urged to move north, as pyroclastic flows in the Belham Valley could produce surges threatening the Friths, Old Towne, Olveston and Salem areas. Large collapse espisodes have in the past lead to explosive activity at the volcano and this remains a possibility.

There is wet ash all over the island this morning and this will make driving dangerous. Also as the ash dries it will start to blow about and the wearing of ash masks is recommended outdoors. Everyone is advised to keep listening to Radio Montserrat for information on the activity.

Montserrat Volcano Observatory