Five (5) events were located in the period under review, 2 volcano-tectonic earthquakes and 3 moderate long-period events. All of these events were located at depths of 0 to 4 km beneath the Soufriere Hills volcano. Small long-period events have been occuring at a rate of one every ten minutes or so throughout the period. A period of moderate amplitude, broadband tremor started at 01:15 on 20 January and lasted until 05:00. Several other signal types have been recorded on both the Gages and Long Ground seismometers; these are thought to be rock falls from the new dome within the crater area.
EDM measurements were completed today on the Windy Hill - Farrell's - St George's Hill triangle. The processing of the data has not yet been finished, although there appears not to be any change in line length on any of the sides of the triangle.
The electronic tiltmeter at Spring Hill was removed today for a thorough overhaul after becoming flooded in late December. A new tiltmeter site is planned and preparation will take place over the next week or so.
Visual observations were made from the helicopter this afternoon during a temporary lifting of the clouds. Continued rock falls were seen from both the northern and southern parts of the new dome. A large piece of spine material and abundant fresh ash were seen in the southern moat after the presumed collapse of part of the spine which had developed in this area over the last couple of days. This collapse may have generated sufficient ash to leave the thin deposit noted this morning in parts of Plymouth and areas to the south.
Drs John Shepherd and Willy Aspinall departed Montserrat today (20 January). Dr Shepherd has been on island since early December, assisting with the upgrade of the EDM network as well as undertaking visual observations of the volcano. Dr Aspinall has been on a brief visit to assist in planning for the future activities of MVO.