Eight (8) events were located during the period under review. These were all long-period earthquakes and were located at depths of 0 to 5 km beneath the Soufriere Hills volcano. Small long-period events continue to occur at a rate of about one every ten minutes or so throughout the period. There were three periods of low amplitude broadband tremor throughout the period; these lasted from 30-50 minutes. At 23:59 on the 20 January, an eruption signal was recorded on the Gages seismograph; associated tremor continued for 30 min after initiation of the signal.
EDM measurements were completed today on the Whites-Castle Peak-Long Ground triangle and on the old Tar River EDM site. The changes in line length on the sides of the Whites-Castle Peak-Long Ground triangle are within the error of the instrument. The Tar River EDM showed 15cm of shortening since its last occupation on the 12 December, 1995. The comparatively large change in line length at this site is thought to reflect the cumulative effect of more than one month of slow dome growth.
Visual observations were made from the helicopter at several time throughout the day. Rock falls continue to occur from the northern parts of the dome with material being deposited in the moat area to the north of Castle Peak. Steady emission of steam was observed from several areas at the top of the dome. A new spine has grown since English Crater was last observed at approximately 1600 on the 20 January. This spine is located on the south western side of Castle Peak dome in the area previously occupied by the September 25th spine. The spine is a single solid mass of rock which is approximately 25m in height and 15m at its base. During successive helicopter flights throughout the day this spine appears to have undergone some disintegration. Material has broken off from the southern face of the spine and a large crack has developed at its base. It is anticipated that this new spine would follow the pattern of rapid growth and collapse which have characterised this period of slow dome growth at English's Crater.