Montserrat Volcano Observatory

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

The level of activity at the Soufriere Hills volcano during this reporting period was higher than that observed during the previous reporting period. The pattern of the activity is still dominated by small- to moderate-sized rockfalls, mainly from the eastern flanks of the growing lava dome.

Eighty seven (87) small- to moderate-sized rockfalls, 17 volcano-tectonic and 8 hybrid earthquakes were recorded. The largest rockfalls occurred at 04:04, 04:51 and 10:20 today, with the rockfall at 10:20 being associated with a small ash cloud. The volcano-tectonic earthquakes occurred in two sequences from 16:00 to 17:25 on 25 August and from 13:35 to 15:00 today. These earthquakes were located at shallow depths beneath English's Crater. Intermittent low-amplitude broadband tremor was recorded at the stations closest to the Crater throughout the reporting period and this is probably due to increased steam emission from the Crater.

The visibility today was variable, with several periods during which the eastern dome flank was visible. Steaming was observed from several areas of the dome. The gully just north of Castle Peak through which material was channelled from the upper areas of the dome is now full. Rockfalls are still occurring mainly from the eastern flank of the dome, and very small rockfall occurrence seems almost continuous. Several areas of the eastern dome look quite unstable.

EDM measurements made today on the eastern triangle reveal shortenings of 6mm and 1cm for the slope distances from Whites to Castle Peak and Long Ground to Castle Peak respectively. COSPEC measurements made yesterday yield an average SO2 flux of 258 tonnes per day.

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