Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 26 August
to 16:00 27 August 1996

Activity at the Soufriere Hills volcano during this reporting period, which is still dominated by small- to moderate-sized rockfalls from the flanks of the growing lava dome, has continued at about the same level as that observed during the previous reporting period.

One hundred and fifteen (115) rockfalls, 7 hybrid, 10 long-period and 30 volcano-tectonic earthquakes were recorded. Most of the rockfalls were concentrated in three periods: from 16:00 to 17:55 on 26 August, 02:00 to 05:00 and 13:00 to 15:00 today. The largest rockfall occurred at 13:52 today and generated a small pyroclastic flow whose associated ash cloud was not dispersed very far from the summit area because of the very light wind. Most of the volcano-tectonic earthquakes occurred as part of a sequence from 00:25 to 01:35 today. Calculated locations place the VTs at shallow depths beneath English's Crater. Episodes of low-amplitude broadband tremor on the seismic records were frequent throughout the reporting period and these were probably due to increased steam emission from the Crater.

The visibility today was very good. Small rockfalls were observed occurring mainly on the eastern flank of the lava dome. The dome was steaming from many areas, with several episodes of vigorous steam and/or ashy-steam emission from the top of the collapse structure being noted. Several areas of the eastern dome look quite unstable.

EDM measurements were made today on the eastern triangle but the data is still being processed. No COSPEC measurements were made today because of the very low winds.

Further rockfalls and pyroclastic flows will occur but all indications at the moment are that the pyroclastic flows 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