Montserrat Volcano Observatory
Morning Report
Report for the period 16:00 15 January
to 07:00 16 January 1997
The current alert level is ORANGE
Further pyroclastic flows occurred in the Tar River starting at 5:30 am.
These flows were the biggest recorded recently, and travelled all the way
down the Tar River valley to the sea. The pyroclastic flows peaked at
about 5:50 pm, and have now stopped completely.
The activity resulted in an ash cloud to about 20,000 ft, which has been blown to the south and west. There has been light ash fall at the Observatory. No ash has fallen on the eastern side of the island. A cruise ship to the south of Montserrat encountered ashfall at 6:30 am.
Before the start of the pyroclastic flows, the seismic activity was at a low level, although 25 volcano-tectonic earthquakes occurred between 5:30 pm and 5:30 am. There were also a few small rockfalls signals.
Observers at Whites have noted that the fan at the base of Tar River is steaming, and appears to be covered by fresh deposits. Small steam explosion have occurred from the surface of the fan. No views of the dome are possible because of low cloud.
The southeastern face of the dome remains unstable, and further collapses and pyroclastic flows are expected. If a major dome collapse happens, it would probably build up over a period of several hours, and could produce large pyroclastic flows in the Tar River valley and heavy ash fall downwind of the volcano. Should the collapse be very large, then an explosive eruption is possible, in the same way that it followed a major dome collapse on September 17/18. At the moment the scientists are confident that zone E, which includes Corkhill and the airport, remains safe. The Tar River area is extremely dangerous, and should not be entered in any circumstances.