The character of the seismic activity, which has dominated the past 13 days, continued throughout the period under review. Hybrid events occurred at a rate of six to seven per minute, about twice the rate of yesterday, and amplitudes were again only slightly variable. In addition to the 8,500 hybrid events which are too small to be locatable , three long-period earthquakes were recorded during this period; one was located between 0 and 1 km beneath the Soufriere Hills volcano. The amplitude of broadband tremor increased somewhat today. Seismic signals which are thought to be produced by rock avalanches were not recognised today, owing partly, perhaps, to this increased tremor level. The total seismic energy release increased slightly during this period to the highest level since early December. One volcano-tectonic earthquake was recorded, but was too small to locate. One regional earthquake with a magnitude of about 3.5 occurred 80-120 km from the island at 03:04 on 31 January.
No EDM measurements have yet been completed today, although the eastern triangle to the Castle Peak reflector is currently being measured. Installation of the dry tilt site at Farrell's continued today and should be completed tomorrow.
Visual observations were made in the early evening of 30 January from the crater rim at Farrell's and Chances Peak and on 31 January from the helicopter. A rock avalanche from the southern part of the dome included glowing blocks which fell towards the southern crater wall, producing an ash cloud which was blown over Gages Wall. Other areas of glowing were generally limited. Observations from the helicopter today showed no major changes but growth continued at both the northern and southern ends of the dome. Continued vertical growth of the dome means that it is now visible from several areas to the north of Plymouth and from Lover's Lane. Residents should note that this situation is not a cause for increased concern.