Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 12 January
to 6 pm 13 January 1998

Seismic activity at the volcano today was very similar to that experienced yesterday. Between 16:00 yesterday and 16:00 today there were 11 hybrid earthquakes, 26 rockfall signals, 3 long-period earthquakes and 2 volcano-tectonic earthquakes. The cyclicity of recent days has broken down somewhat, although there are still distinct peaks in the Real-time Seismic Amplitude Measurements record which correlate with enhanced rockfall activity.

Visibility was again very good for most of the day and more theodolite measurements and photographs were taken of the western and northern flanks of the dome. A helicopter flight around the southwest of the volcano revealed that the new dome has grown very quickly within the Boxing Day collapse scar. It has already filled a considerable portion of the scar and has a large scree slope in the upper part of the White River valley. Work is under way to estimate the dome growth rate since the Boxing Day collapse, although more information will be obtained if the weather remains good.

An EDM survey was also undertaken today and the results should be available tomorrow. Results from yesterday's survey indicate that the Garibaldi to Lees Yard and the Mvo to Lees Yard lines continue to shorten.

The clearer weather today showed that the volcano was still continuously venting ash and steam as was seen yesterday, except that the top of the vertical column reached only about 5 to 6,000 feet. Rockfalls were mainly occurring in the upper part of the White River, but some flows were also seen down the Tar River valley.

Dust monitoring was not carried out today because the equipment had to be taken from the field for data to be downloaded. The program will continue tomorrow.

Chloe Harford from Bristol University in the U.K arrived in Montserrat to assist in the monitoring effort for about one month.

People should remain alert and listen to Radio Montserrat for further information.

Montserrat Volcano Observatory