Montserrat Volcano Observatory

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

Activity at the Soufriere Hills volcano during this reporting period continued at a slightly lower level than that observed during the previous reporting period. Small- to moderate-sized rockfalls from the flanks of the growing lava dome, especially the eastern flank, were dominant on the seismic records.

Forty nine (49) rockfalls, 12 hybrid, 8 long-period and 3 regional earthquakes were recorded. The largest rockfalls occurred at 23:58 on 27 August and 01:25, 11:54 and 13:23 today. These events were associated with very small ash clouds which, because of the very light winds blowing mainly from south to north , led to a sprinkling of ash on some areas in the central and northern areas. The hybrid and long-period earthquakes were small. No volcano-tectonic earthquake was recorded and the level of broadband tremor was low. The 3 regional earthquakes occurred at 07:05, 08:10 and 13:36 today at distances greater than 90 km from Montserrat and had magnitudes of 3.4, 3.5 and 3.7 respectively.

Visibility was generally very good during most of the day. Rockfalls were observed occurring mainly on the eastern flank of the lava dome. Steam was being emitted from several areas of the dome but not as vigorously as yesterday. Several areas of the eastern dome look quite unstable.

No EDM measurements were made today. Yesterday's EDM results for the eastern triangle show shortenings of 1.4cm and 1.0cm for the Whites to Castle Peak and Long Ground to Castle Peak lines respectively. COSPEC measurements were also not made today because of the very light 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