Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 22 August
to 16:00 23 August 1996

The level of activity at the Soufriere Hills volcano during this reporting period has been the lowest observed during the past three weeks. The activity was dominated by small- to moderate-sized rockfalls from the eastern flanks of the growing lava dome.

Fifty one (51) small- to moderate-sized rockfalls and 7 small hybrid earthquakes were recorded. The largest rockfalls occurred at 17:39 on 22 August and 01:14 and 13:38 on 23 August. The events of 17:39 and 13:38 were associated with small ash clouds which were blown westward on the wind, probably resulting in very light ashfalls in the Upper Gages area. Several episodes of low-amplitude broadband tremor were recorded at the stations closest to the Crater throughout the reporting period. A moderate-amplitude broadband signal registered by the Gages seismograph from 07:15 to 07:37 today was caused by flash flooding in Fort Ghaut.

Visibility was very poor throughout the day.

EDM measurements were made today on the lines Amersham to Amersham and Amersham to Chance's Peak Steps. The Amersham - Amersham line showed no change while the Amersham - Chance's Peak Steps line lengthened by 2.9 cm compared to results obtained on 12 August. Yesterday's measurements for the northern triangle indicated a shortening of 1.6 cm for the Windy Hill - Farrells line compared to measurements made on 07 August. No COSPEC measurements were made today because of the poorly developed plume.

Further rockfalls and pyroclastic flows will occur but all indications are that these will be confined to the Tar River Valley area. However, areas affected by associated ashfalls will obviously depend on the direction and strength of the wind at the time. People in areas affected by ash falls should exercise great care when driving. Dust masks should be worn in ashy environments.

The Tar River Valley and surrounding areas are now extremely hazardous, and should not be entered under any circumstances. We urge individuals who continue to ignore this advice to think very seriously before making trips to these highly hazardous zones.

Montserrat Volcano Observatory