Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 on 11 December to
16:00 on 12 December 1995

Seismicity beneath the southern part of Montserrat has remained at a low level throughout this period. Broadband tremor recorded at the Gages seismometer has been at a very low amplitude for most of the period, although occasional intervals of higher amplitude tremor lasting several minutes have been recorded during this afternoon. A long-period event occurred at 13:32 today signaling a small ash eruption; ash fall was confined to the Upper Gages area. Two (2) volcano-tectonic earthquakes were located during this period; both occurred overnight at a depth of about 3 km, one beneath the Soufriere Hills volcano and the otherbeneath Windy Hill.

EDM measurements have been attempted during the day at a number of sites around the volcano. The low cloud level prevented completion of measurement from Long Ground and White's to Castle Peak, from Amersham and Upper Dagenham to Gages wall and from O' Garra's and Galway's Plantation to Chances Peak. Some changes have been made to the lines to Farrells on the northern flank of the volcano which should enable more accurate measurements to be made. This involved the establishment of a new instrument site on St. George's Hill.

GPS surveys continue on a daily basis from sites at St George's Hill, Radio Antilles and Harris Lookout. Processing of the data collected shows that there are at present only very small changes occurring on these lines; these changes are within the limits that can be resolved by this technique.

No visual observations were made today due to the low cloud cover which obscured the crater area all day.

Dr Ellen Howell arrived back on island late yesterday to take over the GPS monitoring work from Dr Don Hooper, who departed this morning.

Montserrat Volcano Observatory