Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 04 February
to 16:00 05 February 1997
The current alert level is ORANGE

Seismic activity at the Soufriere Hills volcano continues at a high level, with a further earthquake swarm this morning, followed by a episode of volcanic tremor. Visibility has been poor, restricting the scientific work of the MVO. The temporary revision of the risk map has been removed, and the map reverts back to the November 1996 edition.

A total of 45 volcano tectonic and 39 hybrid earthquakes were recorded since 4:00 pm yesterday, a similar number to yesterday. Most of these were in a swarm from midnight to 3:30 am. This was slightly larger than recent ones. There were also 29 rockfall signals. The earthquake swarm was followed by a period of tremor from 3:50 am to 5:20 am. This is the eighth time that this pattern has occurred in the last 5 days. No ash fall was detected, but there may have been a small pyroclastic flow.

No observations of the dome or of Galway's Wall were possible because of low cloud. A GPS survey was carried out of the fan at the base of the Tar River valley this afternoon. This will help to determine how much material has been lost from the dome in recent pyroclastic flows.

The temporary revision of the volcanic risk map was removed today, and the map reverts back to the November edition. No access is allowed to zones A and B, which include Tar River, Long Ground, Galway's, St Patrick's, Kinsale and the upper slopes of the volcano. People making short visits to the area of zone C south of Fort Ghaut are warned that further flash floods in the ghaut are possible if there is heavy rain on the upper slopes; people should remain alert and listen to Radio Montserrat, and be prepared to move quickly if necessary. The map will be published in a few days.

The eastern face of the dome is steep, and likely to undergo further collapse soon. Any collapses are likely to be gradual, and follow the recent pattern. However, a larger collapse cannot be ruled out. An explosion similar to that of September 1996 could result in the event of a major collapse which lasted for several hours. Zone E, which includes Cork Hill and the airport, remains safe. The Tar River Valley and the upper Galway's area are very dangerous.

Montserrat Volcano Observatory