Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 02 April
to 16:00 03 May 1997
The current alert level is AMBER

Activity over the past 24 hours has again been dominated by rockfalls and small pyroclastic flows from the active area in the southern part of the dome. Low cloud has again hampered observations of the growing dome.

The broadband seismic network recorded a total of 95 rockfall signals during the past 24 hours, a slight increase from yesterday. The rockfalls have again mainly been occurring on the south-western flank of the dome, shedding material into the upper part of the White River. However, an increasing number of the rockfall signals are being recorded more strongly at Long Ground than at St Patrick's, indicating that they are moving into the upper part of the Tar River valley rather than over the Galway's Wall. There were 24 long-period earthquakes, of which 14 triggered rockfalls. Three (3) volcano-tectonic earthquakes were recorded today. The largest of these events was located at a depth of about 1.5 miles a little to the north of the crater. One hybrid earthquake was also recorded today, the first for almost a week.

Visibility has been poor for most of the day but some brief views of the dome area were possible this afternoon. The top of the dome was not visible, but the focus of growth appears still to be in the southern and southwestern part of the dome. Small rockfalls were seen on the talus slope leading into the Galway's Soufriere area and new material was also noted against the southern crater wall and in the upper part of the Tar River valley on its southern side. Material is probably shedding in a more easterly direction due to the active part of the dome growing in height.

The GPS receiver put in to Perches Mountain yesterday afternoon was retrieved today and the data recorded are currently being processed. This site is the fourth and final one in the closest GPS network, with the other sites showing some small movements of the crater wall area and uppermost flanks of the volcano.

The volcano remains dangerous, and only essential visits should be made to the evacuated zone. People should wear masks when in the ashy areas. The Tar River and White River valleys are extremely dangerous, and should not be entered under any circumstances.

Late News: A pyroclastic flow was observed in the Tar River valley just after 5 pm this afternoon - this flow reached nearly to the Tar River Estate House, but on the southern side of the valley. This flow came totally without warning and demonstrates the extreme dangers of being near to the Tar River or White River valleys at this time.

Montserrat Volcano Observatory