Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 27 October
to 16:00 28 October 1996
The current alert level is AMBER

The activity at the volcano has continued at about the same rate as before. There was another swarm of volcano-tectonic earthquakes overnight. Visibility has been poor, but views of the crater were possible from the helicopter this afternoon.

There were 25 volcano-tectonic earthquakes during the period from 17:20 last night to 01:20 this morning. This is the fourth earthquake swarm since 24 October. Most of these earthquakes were large enough to be located, and occurred at shallow depths beneath the crater.

There were only three rockfall signals today. The number of rockfalls has decreased over the last few days. One long-period earthquake was recorded. There have been very few seismic signals since 01:20 this morning.

The viewing conditions have been poor for most of the day. However, a clearance in the late afternoon allowed some views from the helicopter. The east face of the dome has a blocky appearence, and is shaped like a petal. Some small rockfalls were observed. A small, noisy, rockfall at 10:45 this morning was heard by scientists at the Tar River estate house.

EDM measurements were made from Tar River this morning. This is the first time this line has been measured since the reflector was replaced, and so the results cannot be compared to previous measurements. Surveys of the Tar River valley were made from the estate house using the laser range-finding binoculars. These profiles will help to measure the amount of dome material that is now in the valley.

Further COSPEC measurements were conducted this morning and afternoon. The data is currently being processed. Yesterday's measurements gave an average flux of 434 tonnes per day of Sulphur Dioxide emission. This is a similar to measurements made during recent days.

Further calculations on the volume of the October 1 dome have been made. The dome volume was 3.7 million cubic metres on 23 October. The rate of dome growth between 1 and 18 October was 1.8 cubic metres per second, although it was slightly higher than this during the first few days of growth.

The volcano remains in an active and highly dangerous state. Further activity, possibly leading to an explosive event could occur with little warning in the near future. Everyone who enters the evacuated zone must remain alert and be ready to move at short notice. Individuals who go beyond the Long Ground area into the Tar River valley are risking death.

Dr Simon Young of the British Geological Survey returned to Montserrat today after a 3 week visit to the United Kingdom.

Montserrat Volcano Observatory