Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 2 January
to 16:00 3 January 1997
The current alert level is ORANGE

The October 1 dome continues to grow at a fast rate. Numerous rockfalls and small pyroclastic flows were recorded during this reporting period. These included, between 1 and 2 pm today, perhaps the largest flows since growth of this dome resumed on 20 December. The upper flanks of the dome are becoming very steep and conditions may be favourable for larger dome collapses. Larger pyroclastic flows are therefore likely over the next few days. These may lead, without warning, to an explosive eruption similar to that on 17 / 18 September 1996. Residents must therefore stay vigilant and follow the alert procedures. There is no access to zone A/B and only limited access to zone C/D.

Visibility has been moderately good today. There were numerous rockfalls and small pyroclastic flows from the October 1 dome, coming from all parts of the visible north-east and eastern faces. Much of this activity has been channelled into the Tar River valley down either the erosion chute over the top of Castle Peak or to the north of Castle Peak. There was a peak in the pyroclastic flow activity between 1 and 2 pm. Small pyroclastic flows were seen to occur about every ten minutes. The largest travelled perhaps 1,000 ft past the Tar River Soufriere. The ash clouds produced during this phase of activity were more dense and buoyant than during the rest of the day. The largest reached altitudes of about 6,000 ft above sea level. There was a slight lull in rockfall activity after 2 pm, but activity picked up again at about 3:40 pm.

The upper flanks of the dome, seen during an inspection from the helicopter, are becoming very steep. This oversteepening could lead to larger-scale collapses of the dome and larger pyroclastic flows into the Tar River valley.

Seismic activity was dominated by rockfall signals. 91 were recorded today, which is a significant increase over yesterday. Most of them were smaller than yesterday. However, the rockfalls recorded during the peak in visual activity between 1 and 2 pm were the largest seen since the restart of growth of the October 1 dome on 20 December. There were also 43 small hybrid events and 2 small long-period events recorded during this reporting period.

Theodolite measurements and photographs of the dome were taken again today, in order to estimate its rate of growth. Surveys of the debris fans from the October 1 dome were carried out using laser-ranging binoculars from the helicopter. These will provide an estimate of the amount of material that has been lost from the dome during the current phase of activity.

Lutchman Pollard returned to Trinidad today at the end of his tour of duty at MVO.

Montserrat Volcano Observatory