Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 12 February
to 16:00 13 February 1997
The current alert level is ORANGE

Volcanic activity has continued at a low level. There was a swarm of earthquakes overnight, followed by a short episode of tremor. Views of the dome have been restricted by low cloud. There have been more rockfalls from the dome over the Galway's Wall, and the top of the wall has crumbled further.

The swarm of earthquakes lasted from 8:40 pm to 6 am. The first part of the swarm was dominated by volcano-tectonic earthquakes, with a total of 92 recorded, and then 34 hybrid earthquakes were recorded in the last two hours of the swarm. A short episode of tremor began at 6:30 am, and finished at 7:15 am. The tremor peaked at 6:50 am with a signal that may have been a small pyroclastic flow; however the visibility was not good enough to confirm this. The level of rockfalls was low, with only 10 recorded.

Visual observations today were restricted by low cloud. Some views of the dome were possible, and there do not seem to have been many changes since yesterday. Further changes to the Galway's Wall were seen, with the top of the wall crumbling some more, and more dome material falling over the wall. A few small rockfalls were observed from the helicopter, and these created small ash clouds. The deposit from these rockfalls reaches one kilometer from the wall, and reaches almost to the Galway's Soufriere. It has not extended further since the last view a few days ago, but the deposit is wider.

Gravity measurements were made today from Bethel to Tuitt's Ghaut and also around the White's area. The northern EDM triangle was measured, and only small changes were detected since the last measurement on 22 January.

Despite the low level of activity, more pyroclastic flows are expected from the steep eastern face of the dome. Any collapses are likely to be gradual, and produce small or moderate pyroclastic flows. However, a larger and more prolonged collapse can not be ruled out. Residents are reminded to remain alert and responsible at all times, carry ash masks and spend the minimum possible time in the evacuated zone. Zone E, which includes Cork Hill and the airport, remains safe at this time. The Tar River Valley and the upper Galway's area are very dangerous.

Montserrat Volcano Observatory