The level of volcanic activity at the Soufriere Hills volcano has been at a much lower level during the past 24 hours. There was one earthquake swarm, but no episodes of tremor. There was one pyroclastic flow in the Tar River valley.
The earthquake swarm consisted mainly of hybrid earthquakes, with 161 recorded in total during the period. There were also 9 volcano-tectonic earthquakes and 47 rockfall signals. The swarm occurred between 10:30 pm and 3:50 am. Unlike all previous earthquake swarms in the last week, last night's swarm was not followed by volcanic tremor. Since then end of the swarm the level of seismic activity has been low, with only a few moderate rockfalls recorded.
Visibility has been poor today, which has restricted observations. There was one sizeable pyroclastic flow just before 11 am, which reached past the Tar River estate house, and resulted in a heavy fall of wet ash in Plymouth. The dome has not changed much since yesterday. Some blocks on the new extrusion have moved further downhill, and there has been constant ash production from the steep eastern face of the dome.
The COSPEC measurements made on 6 February gave an average sulphur dioxide flux value of 450 tonnes per day. This is similar to recent measurements.
The eastern face of the dome is steep, and likely to undergo further collapse soon. Any collapses are likely to be gradual, and follow the recent pattern. However, a larger collapse cannot be ruled out. An explosion similar to that of September 1996 could result in the event of a major collapse which lasted for several hours. Zone E, which includes Cork Hill and the airport, remains safe. The Tar River Valley and the upper Galway's area are very dangerous.