Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 5 November
to 6 pm 6 November 1997

Today there was another substantial collapse down the White River. Seismic activity remained at an elevated level until these pyroclastic flows at 2:30 pm, since then seismicity has been low.

The hybrid swarm which started at about 5 o'clock in the afternoon on the 4th of November continued until 8 o'clock last night. From that time the seismicity was dominated by high amplitude tremor until 2:30 this afternoon, when the pyroclastic flows occurred. This tremor had similar frequency content to the individual hybrids which preceded it and so can be assumed to have a similar seismic source to that of the hybrids. In the 24 hours before 4 o'clock this afternoon 38 hybrid earthquakes and 11 long period earthquakes were recorded.

The pyroclastic flows this afternoon again reached the sea down the White River. Although they did not go on for as long as those two days ago they were observed to be more energetic. Large rockfalls or small pyroclastic flows occurred in the Tar River Valley and down Gages Ghaut at the same time as the main flows were going down the White River. The ash cloud from the flows, as well as from ash venting which occurred at the same time, reached 15,000 feet and drifted West.

The dome was very clear for most of today and a successful GPS survey was carried out to map its surface. The results of this survey will be known in the next few days.

Although the volcano is quiet at the moment it is likely that another hybrid swarm will start soon. If this happens then more pyroclastic flows can be expected. There is also a chance that the volcano will start exploding again. At the present time ash levels in the air remain low at less than 50 micrograms per cubic metre. Stay tuned to Radio Montserrat for further information.

Montserrat Volcano Observatory