Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 5 December
to 16:00 6 December 1996
The current alert level is ORANGE

The level of seismic activity has decreased slightly during the last 24 hours, although the number of earthquakes remains high and large earthquakes are still occurring. The decrease in the number of earthquakes does not lessen the risk of a significant event during the next few days. The Galway's Wall has become more unstable. A major collapse of the wall might expose hot, gas-rich magma from the lower sections of the dome, and trigger a lateral blast. This blast could occur in a number of directions from the crater and affect a large part of southern Montserrat.

A total of 188 volcano-tectonic earthquakes have been recorded, a reduction in numbers since yesterday. The maximum magnitude of the earthquakes has remained about the same. There were nine landslides from the Galway's Wall that were large enough to be detected by the seismic network. Three dome rockfalls were also recorded.

A helicopter inspection of the Galway's Wall was made this morning. A major landslide occurred overnight from the central part of the wall. This was probably associated with a strong seismic signal at 8:24 am today. Some new cracks in the lower part of the wall were seen for the first time. During the inspection flight, a VT earthquake shook the wall and caused several small landslides.

The crater area was not visible today because of low cloud, which also prevented any EDM measurements from being made.

The GPS experiment on the eastern side of the volcano yesterday showed no changes in line lengths since they were last measured. These results are consistent with previous measurements, which have not detected any large-scale deformation of the volcano.

Montserrat Volcano Observatory