Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 08April
to 16:00 09 April 1997
The alert level was changed to AMBER this morning.

The level of volcanic activity is low, with continued moderate pyroclastic flow activity from the south of the dome. Another day of excellent visual conditions have allowed very clear views of the volcano.

The volcano has been clear, with a steam plume rising almost straight up for most of the day. The size of the plume has varied during the day, suggesting that the amount of gas emission has been changeable, and probably lower than yesterday. There may also be an atmospheric effect which changes the apparent intensity of the plume through the day. Low amount of steaming and gas emission was also observed from area around the flanks of the dome.

Accurate measurements of the dome surface show that a block on the top of the new extrusion has moved 30 metres (almost 100 ft) to the south since yesterday. The front face of the new extrusion has advanced to the south, and most of the Easter scar is now filled.

Signs of fresh landslides on the outside of Gages Wall were seen from the helicopter today. Some of the cracks in this area appear to be getting wider. These will be watched for any further developments.

Seismic activity has been at an extremely low level, with only 1 volcano-tectonic earthquake recorded, and 27 rockfall signals. Most of the rockfalls were associated with small pyroclastic flows over Galway's Wall. There were two slightly larger flows, at 11:53 am and 3:26 pm, which resulted in ash clouds that rose to heights of about 7000 ft and were dispersed to the north-west by the light winds.

A GPS survey was carried out today at sites around the volcano. The results will be processed shortly.

COSPEC measurements were attempted today, but were unsuccessful due to the wind direction. The measurements from two days ago were processed, and gave an average sulphur dioxide flux of about 225 tonnes per day.

Despite the decrease in alert level, the volcano still remains dangerous. The dome is large, and a major collapse could start at any time. Daytime visits to zone C should be kept short, and nobody should enter zone A, which includes St Patrick's and Long Ground. People should remain alert and continue to use ash masks when necessary.

Montserrat Volcano Observatory