One (1) earthquake was located during the period. It occurred at 05:31 today, and was located at a depth of about 3.5 km beneath Windy Hill. A regional earthquake (magnitude 3.1) was recorded at 13:01 and was located about 160 km (100 miles) from Montserrat. Broadband tremor was recorded at the Gages seismic station from 02:30 and it is still continuing. It had unreduced peak-to-peak amplitudes of 2-7 mm, and is due to increased steam emission from the crater. A mudflow signal was recorded at Gages at 22:40 on 10 Dec.
Measurements of the EDM lines to Castle Peak were made this morning and slight shortening of a few millimetres was detected. The Amersham lines were measured this afternoon, but the results are not yet available. GPS measurements were again made overnight at stations at Harris' Lookout, Radio Antilles Aerial and St. George's Hill. The results will be reported tomorrow.
Visual observations were attempted from the crater rim and from the helicopter. No major dome growth was detected. A small rockfall was observed from the new dome into the moat. Variable steam emission was observed from several areas, especially from the vent near Castle Peak. Four ash eruptions were observed at 09:10, 14:55, 15:30 and 16:04 today, with the 16:04 eruption being the largest. The ash was a rusty brown colour, and fell in the Upper Gages and Amersham areas.