Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 18 November
to 16:00 19 November 1996
The current alert level is AMBER

Activity at the volcano continued at a low level during the past 24 hours, although there was a small swarm of VT earthquakes.

Ten VT earthquakes were recorded by the seismic network today, starting at 06:30 this morning. The swarm lasted throughout the rest of the day, although the rate of activity was very low, peaking at two events per hour between 13:00 and 15:00. All the VT earthquakes were located at shallow depths beneath the crater, very similar to the swarm activity seen since 1 November. Only one small rockfall signal was recorded. There was intermittent low level tremor recorded on the Gages seismic station throughout the reporting period.

Visibility was poor for much of the day with the summit obscured by clouds. Some observations of the dome were made from the ground but it was not possible to see any large changes since yesterday.

No EDM measurements were carried out today because of the poor visibility. A helicopter survey of the dome had to be abandoned for the same reason.

A series of four COSPEC measurements were taken this morning. These indicated a sulphur dioxide flux of an average of 250 tonnes per day, slightly lower than the last measurement. The amount of sulphur dioxide coming from the volcano has been quite low since 31 October, averaging below 400 tonnes per day.

The scientific data gathered over the last few days shows that the risk of a sudden explosion on the dome has decreased significantly. The VT seismicity has declined to a very low level and there is a renewal of dome growth. This morning the scientists at MVO recommended that the level of alert should be reduced and the authorities announced the change from Orange to Amber at 10:00.

We must however remind everyone that the volcano is still in a very dangerous state and that residents should follow the recommendations laid out in the alert procedures and listen to Radio Montserrat. The renewed growth of the dome means that rockfall activity is likely to continue and there may be pyroclastic flows into the Tar River Valley. These will generate ashfall downwind of the volcano. The Tar River and Long Ground areas remain especially dangerous and anyone entering these areas is putting themselves at risk of death.

The sirens will be tested between 3 and 6 p.m. tomorrow. They will be tested at the same time every Wednesday.

Montserrat Volcano Observatory