The level of activity at the Soufriere Hills volcano has decreased over the last 24 hours. The hybrid earthquakes that have been recorded during the last week have become less frequent, with one earthquake occurring every two minutes during this afternoon. The size of the hybrid earthquakes has increased slightly. Only a few small explosive signals were recorded.
Observations of the volcano have been restricted by low cloud today. A few rockfalls were observed, and these resulted in small ash clouds. The remnant of the recent large spine remains in place, and another spine to the east that was first reported yesterday appears to have grown slightly during this period. The dome was steaming vigorously today from several locations, probably because of the recent rainfall. During a late afternoon helicopter flight, it was observed that the eastern part of the dome is still glowing. There are several large unstable blocks at the top of the slope in this area, and so further rockfalls to the east are to be expected.
GPS measurements were made today of the northern network, which extends round the volcano from Tar River to St George's Hill. This is the second time that the network has been measured. The line lengths are now being calculated and will then be compared with the previous measurements. The results will be reported tomorrow.
EDM measurements were made of the northern triangle. The results agree with the measurements made yesterday, which showed a slight line shortening since the triangle was measured two weeks ago. The lines to Farrell's have shortened by about 1 mm/day over the last two weeks, following an extended period of only very slight changes. The northern EDM triangle measurements will be repeated again over the next few days to check that this change is real.
Despite the slight decrease in activity today, the Soufriere Hills volcano still remains highly dangerous, and further major explosive activity could commence with little warning. The MVO scientists continue to urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas remain very dangerous, and people are advised not to enter these areas under any circumstances.