Montserrat Volcano Observatory

Morning Report
Report for the period 8 pm 05 August
to 7 am 06 August 1997

Activity at the volcano overnight has remained at a very high level with a hybrid swarm and continued explosive and pyroclastic flow activity. A hybrid earthquake swarm this morning was followed by an explosive eruption and pyroclastic flows at 4:02 am.

The hybrid earthquake swarm started at just after 1:30 am, and continued until after 4 am. The swarm was shorter in duration than previous swarms and did not contain the same distribution of magnitudes.

At 4:02 am, a vertical eruption column quickly rising to over 10,000 feet was observed from the MVO and an audible rumbling lasted for about 5 minutes. Lightning was observed in the eruption column, and a loud boom was heard at the observatory. Unlike events from yesterday, fallout was not observed in Old Towne. Pyroclastic flows followed closely after the eruption column. Incandescent material was observed at the head of the Gages valley, Tuitt's Ghaut and Mosquito Ghaut.

After the peak of eruption a few more hybrids occurred and a following phase of long period tremor continued for over an hour.

The activity is still generally following a cyclical pattern with regular inflation and deflation of the volcano corresponding to the earthquake swarms on the inflationary part of the cycle. The explosions occur as the cycle reaches its peak. However, pyroclastic flows have also occurred outside the most probable time period, and so at no time is it safe to enter the exclusion zone, including the Belham river valley. The risk of further explosive eruptions remains high and the present pattern of activity is expected to continue.

There is ash in the air in the west of Montserrat and therefore dust masks should always be worn in these areas. Drivers should also be considerate whilst driving in ashy conditions. The Belham River valley is very dangerous and should not be entered. Access to the exclusion zone is completely restricted, and people should stay completely away from all the flanks of the volcano. Everyone should continue to stay alert, and listen to Radio Montserrat for any announcements.

Montserrat Volcano Observatory