Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 28 January
to 16:00 29 January 1997
The current alert level is ORANGE

Volcanic activity has continued at a low level during the last 24 hours. The rate of dome growth seems to have slowed since yesterday. There was one swarm of volcano-tectonic earthquakes; otherwise the level of seismic activity has been low.

Visual observations were made today from both the ground and the helicopter. The top of Galway's Wall has lowered slightly over the last few days, so that there is now a section of the wall where the old dome rock is flush with the top of the wall. There has been continued collapse of small amounts of dome material over the wall. Some new cracks were seen on the wall.

The new dome extrusion has not changed much in shape since yesterday, although there seems to have been more extrusion above Castle Peak and in the north-east part. There were some rockfalls today down the Castle Peak chute, and also some small pyroclastic down the chute to the south of Castle Peak. There have been some changes, and perhaps slight opening, of the large crack that was observed a few days ago across the north-east sector of the October 1 dome. The northern side of the dome is more active, with some vigorous steaming.

There was one swarm of shallow volcano-tectonic earthquakes between 5:30 am and 7:50 am today, with 28 earthquakes. The level of other seismic activity was very low, with only 8 dome rockfalls. Two landslides from the Galway's Wall were detected by the seismic network. There was a magnitude 4 regional earthquake just after 4 am, which was located to the north-east of Antigua.

The results from yesterday's dome survey show that the rate of extrusion between 26 and 28 January was 3.5 cubic metres per second, about the same as the last determination. A theodolite survey of the new extrusion was made from Whites and Harris.

As the new extrusion in the south-east of the crater continues to grow, it is likely that it will collapse and cause further pyroclastic flows in the next few days. Although the dome is likely to collapse gradually, a larger collapse cannot be ruled out. An explosion similar to that of September 1996 could result in the event of a major collapse. It is however expected that there would be several hours of high level pyroclastic flow activity before any explosion. Zone E, which includes Cork Hill and the airport, remains safe. The renewed crumbling of Galway's Wall means that the upper Galway's area is very dangerous.

Montserrat Volcano Observatory