Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 04 September
to 16:00 05 September 1996

Activity at the Soufriere Hills volcano during this reporting period has been at a slightly lower level than that observed during yesterday. Rock falls have continued throughout the day, the largest of which have led to the generation of pyroclastic flows within the Tar River valley.

Seismicity during the day has been dominated by volcano tectonic earthquakes, of which there were 179 during the past 24 hours. These occurred in two distinct swarms, the first between 16:13 and 22:00 last night (4 September) and the other between 05:40 and 08:49 today (5 September). All of these events were located beneath the crater at depths of 1.5 to 2 km. Rock falls have also been recorded throughout the day, though at a lower rate of occurrence than over the past few days; a total of 47 were recorded during the reporting period. A period of near-continuous rock falls occurred between 09:45 and 10:14 this morning, with the pulse at 10:02 producing the largest pyroclastic flow of the day. One long period event and 8 hybrid events were also recorded. Broadband tremor was intermittent during the period, with a peak on the Gages seismometer between 05:12 and 05:54 this morning associated with flash flooding in Fort Ghaut.

Visibility during the day was poor, and no observations of the dome were possible. The largest pyroclastic flow of the day was reported to have reached the new delta built out at the end of July from the mouth of the Tar River. The top of the associated ash cloud could not be seen but it drifted westwards from the volcano over Plymouth and surrounding areas.

EDM measurements were not made today due to the low cloud.

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. Dust masks should be worn at all times in ashy environments, and drivers should exercise caution and consideration for other road users.

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

Montserrat Volcano Observatory