Forty-four (44) earthquakes were located during the period under review. The earthquake depths were in the range 0-6 km. Most of the events were concentrated beneath the Soufriere Hills Volcano with a few located beneath St. George's Hill. The events were mainly volcano-tectonic, and thirteen (13) long period events were also recorded. A change in seismicity has benn observed since 11/11/95, when there was a marked increase in the daily number of located events, and also in the number of small earthquakes recorded only at the Gages seismic station. The seismicity has followed a cycle that lasts for 6 to 10 hours, with a gradual increase in the rate of occurrence of earthquakes that culminates in an eruption signal.
An eruption signal was recorded at 16:03 on the 13/11/95 and a small ash cloud was observed, which drifted north-west.
The Tar River, Amersham and O'Garro's and Galloway's EDM lines were measured today. The Tar River line continues to shorten at a higher rate than the trend over the last few weeks. The other EDM lines all show increased rate of shortening since they were last measured.
Visual observations of the crater were made from Chance's Peak this afternoon. The three new vents first observed on 12/11/95 were still emitting steam. Most of the steam was coming from the vent closest to Castle Peak, which has increased in size and has fresh ash around it, probably from the eruption at 16:03 yesterday.
The changes in seismicity and EDM measurements may suggest the start of an intrusion, but so far there have been no surface manifestations to confirm this.
Late Note: A small eruption occurred at approximately 16:10 today and minor ash and steam emissions from the crater were visible, initially from the Tar River area.