Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 25 July
to 16:00 26 July 1996

Activity at the Soufriere Hills volcano has continued at a slightly lower level than that observed during the past several days.

The seismicity is still dominated by small- to moderate-sized rockfalls from the flanks of the lava dome. One hundred and two (102) rockfalls were recorded during the reporting period. The largest rockfalls occurred at 17:36 and 23:26 on 25 July and 01:30, 12:52, 15:50 and 15:59 on 26 July. Some of the rockfalls were associated with very small ash clouds which were blown on the wind towards the west, over the Upper Gages area.

Ninety eight (98) small volcano-tectonic earthquakes were recorded. Most of these events occurred in a single burst of intense activity between 06:30 and 09:30 this morning. Calculated locations are generally beneath the crater at shallow depths (less than 3km). The numbers of hybrid and long period earthquakes were 15 and 5 respectively and these were generally of small size. The nearest stations to the crater also recorded intermittent low- to moderate-amplitude broadband tremor throughout the reporting period but the level was the lowest since 20 July.

Visibility was generally poor during most of the day although there were brief periods of partial cloud clearance from some parts of the dome. Rockfalls were observed on the eastern, northeastern and southeastern flanks of the dome.

EDM measurements were made on the eastern triangle today and these show a shortening of 3 cm of the lines from Whites and Long Ground to Castle Peak in two days. GPS measurements were also made but the results are not yet available. COSPEC and FTIR measurements of the volcanic gases were made, but the data is still being processed. No gravity measurements were made.

The Soufriere Hills Volcano is still considered to be 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 and Long Ground areas to the east and upper Fort Ghaut, Gages Village and Upper Amersham areas to the west are all extremely dangerous. All access roads to these areas 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