Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 27 July
to 16:00 28 July 1996

Activity at the Soufriere Hills volcano during this reporting period was higher than that observed during the previous 24 hours. Several large rockfalls and small pyroclastic flows occurred in the the Upper parts of the Tar River Valleys, resulting in small ashfalls in several areas of western and northwestern Montserrat.

Three periods of near-continuous small- to moderate-sized rockfall activity occurred from 16:24 to 18:50 on 27 July, 22:12 on 27 July to 00:30 on 28 July, and 02:59 to 04:04 on 28 July. From 06:39 on 28 July, the activity again increased and at 07:09, a small pyroclastic flow occurred in the upper reaches of the northern Tar River Valley area. A slightly larger pyroclastic flow occurred at 09:13. Other smaller pyroclastic flows in the Tar river valley may have occurred at 11:51, 12:36 and 13:04. Signals interpreted as representing large rockfalls were recorded at 16:29, 18:06, 20:23 and 20:26 on 27 July and 03:02, 03:54, 05:16, 06:38, 10:05 and 10:15 on 28 July. From 14:00 to 16:00, activity was slightly lower, with fewer rockfalls. The large rockfalls and pyroclastic flows resulted in a near-continuous ash cloud which which was blown to the west and northwest, with small ashfall in Upper Gages, Amersham, Plymouth, Richmond Hill, St. Geoge's Hill, Cork Hill, Garibaldi Hill and Fox's Bay. Five (5) volcano-tectonic earthquakes were recorded during this period but none was large enough to be located. Several small hybrid and long-period events were also recorded. Broadband tremor was intermittent and of low- to moderate-amplitude.

Visibility was generally very poor during the whole reporting period because of low cloud cover and episodic rainfall. However, brief glimpses of the upper reaches of the Tar River Valley area revealed that the pyroclastic flows were from the eastern and northeastern parts of the lava dome and that green trees were also set alight.

GPS measurements were made but the results are not yet available. FTIR measurements of the volcanic gases were also made but the data is still being processed. No gravity, EDM or COSPEC 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