Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 15 August
to 7 am 16 August 1997

Activity at the volcano has remained at a high level with continuing hybrid swarms and pyroclastic flows. The swarm which began at around 3 pm yesterday afternoon continued until around 7:30 pm last night. This was followed by a relatively quiet period when only a few rockfall signals were detected.

Hybrid activity resumed at around 11 pm last night and developed into another swarm which lasted until about 4 am this morning. Following this swarm there have been several signals which are interpreted as rockfalls and small pyroclastic flows. It is not known currently where this activity took place. An ash plume was partially visible extending out to sea off the west coast of Montserrat.

Current activity is characterised by isolated hybrid events indicating that another swarm is approaching. The volcano summit is obscured by cloud at present although a steam plume can be seen drifting westward.

The recent hybrid earthquake swarms are thought to be associated with rapid extrusion of new dome material. It appears that small explosions are also taking place as new magma increases the pressure within the dome.

Further explosions may take place with little or no warning. These may be more intense and longer lasting than those already experienced. If explosions do occur, the central zone should be evacuated immediately and people in the northern zone should seek shelter under as strong a roof as possible. After an explosion small rocks and ash can be expected to fall everywhere on the island. Ash and falling rocks make driving hazardous. Ash is present in the atmosphere and masks should be worn outdoors.

Pyroclastic flows are expected on all flanks of the volcano, and so at no time is it safe to enter the exclusion zone, including the Belham river valley. Access to the exclusion zone is completely restricted. The central zone is evacuated over night and people should not return to their homes until advised to do so. Everyone should remain vigilant and continue to listen to Radio Montserrat for any announcements.

Montserrat Volcano Observatory