Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 12 December
to 16:00 13 December 1996
The current alert level is ORANGE

The situation at the volcano has changed during the last 24 hours, with a new spurt of dome growth forming a new dome to the south of the October 1 dome, close to the Galway's Wall. The dome is believed to have emerged during 13 December after the reduction in seismic activity. The seismic activity has been very quiet. This sudden change in activity makes pyroclastic flows in the Tar River valley more likely. New cracks have formed at the eastern side of the wall, at Galway's Mountain, making the Galway's Wall even more unstable.

The observations provide further evidence that Galway's Wall is coming closer to failure, which may trigger a lateral blast. Areas A/B on the risk map are very dangerous, and nobody should enter these areas. Residents of zone E must remain alert, as the conditions could change suddenly and require the evacuation of zone E. At this time, the scientists are confident that zone E remains safe.

Only two volcano-tectonic earthquakes have been recorded since yesterday afternoon. No major landslides on the Galway's Wall were measured by the seismic network.

A visual inspection of the dome area was made during excellent viewing conditions this morning. A new dome, to be called the December 13 dome, has appeared during the last two days, to the southern side of the October 1 dome, between Castle Peak and the Galway's Wall. This dome was surveyed this afternoon, and a volume is being calculated.

New fractures were seen today at Galway's Mountain, at the eastern end of the Galway's Wall. These fractures are parallel to the crater wall, and run for a length of about 100 m, and are about 1 m (3 ft) wide. They are similar to the fractures that were first seen on Chances Peak last week. New fractures on the Galway's Wall were seen today. Most of these fractures are along the wall.

This morning, signs of a major landslide from Galway's Mountain into the crater were seen. The lowest part of the top of the wall is now only about 1 metre (3 feet) above the talus of the dome.

EDM measurements were made on the eastern triangle this morning. The results show the lines to Castle Peak have shortened by about 4 cm since they were last measured on 4 December. This rate of shortening is slightly lower than recorded last week.

Montserrat Volcano Observatory