Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 on 12 December to
16:00 on 13 December 1995

The level of seismicity has remained low throughout this period. There have been several small long-period earthquakes recorded at the Gages seismometer, and some periods of low-amplitude broadband tremor. About 6 larger long-period events also occurred throughout the period.- Many of these were associated with ash clouds. One (1) volcano-tectonic earthquake was located, at a depth of about 1 km beneath the Soufriere Hills volcano.

EDM measurements have been made today at Castle Peak, Farrell's and Amersham. The low cloud level prevented measurement of the Gage's Wall and Chances Peak lines. The triangle of lines between Farrell's, Windy Hill and St George's Hill was fully installed and measured completely for the first time. Recent results from the Castle Peak triangle suggest that the swelling of the volcano has stopped, and that slight deflation may be occurring. The measured deflation is still within the errors of the method, and further measurements are required.

GPS surveys continue on a daily basis from sites at St George's Hill, Radio Antilles and Harris' Lookout. Results from yesterday show a lengthening of about 2 cm of the lines to Harris' Lookout over the last 6 days. Processing of today's results is not yet complete.

Visual observations were made early today from the helicopter. Vigourous steaming was observed frommost of the central part of the crater. A small radial crack on the northern flank of the dome in the July 18th vent was emitting ash continuously. No major changes to the dome were noted. Ash clouds were observed coming from the crater several times today, and was probably continuous for much of the day. Most of the depositon of ash occurring in the Upper Gages area.

Montserrat Volcano Observatory