Seismic activity at the volcano has declined noticeably during this 24 hours. At the start of the period, the number of small repetitive hybrid earthquakes was increasing slightly and this continued until it reached a peak of about one event every 40 seconds at approximately 20:00 on 26 April. After that time, the rate gradually decreased to about one every three or four minutes at 16:00 on 27 April. The number of small to moderate sized seismic signals interpreted as rockfalls continued to increase up until an episode of low-amplitude broadband tremor between 06:10 and 07:50 on 27 April. There were noticeably fewer rockfall events after that. One small volcano-tectonic earthquake occurred at 15:47 on 27 April and was located in the Amersham-Broderick's area at a depth of 4 km.
The eastern EDM triangle was measured today. The results show that the slow shortening trend seen since the end of November continues. No GPS measurements were made.
Observations have been hampered by poor visibility for much of the day, but many of the rockfall events seen on the seismographs have been accompanied by small ash clouds which drifted into the Upper Gages Valley. The largest rockfalls seem to have occurred between 10:00 and 12:00 on 27 April. A helicopter inspection at around 13:00 on 27 April showed that there had been a large rockfall on the southwestern flank of the dome. Steam production was still high.
Despite the decrease in seismic activity, the level of activity at the Soufriere Hills volcano is still very high and scientists continue to view the situation with grave concern. The MVO continues to urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.