Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 6 July
to 16:00, 7 July 1996

There was very little change in the level of seismicity at the Soufriere Hills Volcano. Small rockfalls from the dome continue to dominate activity and there were some hybrid and long period earthquakes. Observations made today show that the dome continues to grow and that the activity is concentrated in the south.

There was a slight increase in the number of rockfall events recorded today; 22 compared to 11 yesterday. The two most notable rockfall events were at 22:09 and 22:10 on July 6 and both had durations of about one minute. Hybrid earthquakes and long-period earthquakes continue to occur at roughly the same level as yesterday, with 6 and 12 respectively. There were also two VT earthquakes recorded during this reporting period. The first of these, at 19:54 on July 6, was located to the north of English's Crater at a depth of about 0.3 km. The second occurred at 22:05 on July 6 and was too small to be located. Two periods of fairly vigorous tremor were recorded, from about 22:10 to 23:30 on July 6 and from 23:55 on July 6 until 01:00 on July 7. These occurred during thunderstorms last night and were probably associated with heavy rainfall at the summit and an increase in steam venting. There was also some intermittent tremor between 11:00 and 14:00 on July 7.

Viewing conditions were poor for most of the day. There was a short period in the afternoon when the entire dome became visible. Activity is now clearly concentrated on the southern part of the dome. The amount of activity there has been enough to build a second peak on the dome, which is at least as high as the main peak. Rockfalls seem to be concentrated on the southern side of this southern peak, and material is now building up behind Galways Wall. It is estimated that there is about 30 ft left before the wall is overtopped. There was a lot of fumarolic activity in the saddle between the two peaks. The northern parts of the dome appear very inactive, although almost all the flanks are still very steep and therefore have the potential for rockfall activity.

No EDM measurements were possible today because of the poor visibility. The height to the top of the dome was measured as 3082 ft. No GPS measurements were carried out. Processing of the GPS data from yesterday has been completed and shows that there have been no significant movements on the eastern side of the volcano since the last occupation on June 18. No COSPEC measurements were made today.

MVO staff were kept busy preparing for the arrival of Tropical Storm Bertha. The University of Puerto Rico GPS equipment was retrieved from the field and solar panels have been removed from some of the seismic stations.

The Soufriere Hills Volcano is still highly dangerous to people and property on it's eastern and upper western flanks. Visits to the evacuated zone must be kept to a minimum. The Tar River, Long Ground and Whites areas to the east and upper Fort Ghaut, Gages Village and Upper Amersham areas to the west are all extremely dangerous. All access roads remain closed and people should not enter these areas under any circumstances. If they do, they put themselves and others at direct risk of serious injury or death.

Montserrat Volcano Observatory