Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 7 December
to 16:00 8 December 1996
The current alert level is ORANGE

The VT swarm which started on 30 November stopped at about 05:30 am. Activity has apparently been at a low level since. There may, however, be activity in the crater that cannot be seen due to cloud cover. It is far too soon to say whether the end of this swarm marks the end of the current phase of activity or is just a temporary respite. In any case, the Galways Wall remains unstable and liable to a sudden collapse. A major collapse of the wall could 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. There is also a small possibility that a vertical eruption column could be generated during any heightened activity. All residents of Montserrat are urged to follow the alert procedures. The revised risk map is still in operation and there is no access into Zone A/B. Access to zone C/D is restricted to short visits for essential purposes.

A total of 98 volcano-tectonic earthquakes were recorded in this reporting period. 97 of these occured before 05:26 this morning. Up to then, activity had been at an unchanged level, similar to that over the last two days. All the events were located at shallow depths beneath the crater. Seismic activity stopped abruptly and only one small VT has been recorded since. There were seven landslides from the Galway's Wall that were large enough to be detected by the seismic network. One dome rockfall and one small long-period event were also recorded. The Gages seismometer recorded semi-continuous, low-amplitude tremor up until about 1 pm today. Lesser amount of tremor were recorded during the rest of the day.

Helicopter inspections of the Galway's Wall were hampered by poor visibility. There was evidence that landslides from the wall continue. There had also been a small landslide on the inside of Farrell's wall, on the north side of the crater. The crater area was not visible because of the low cloud.

No EDM measurements were made today.

Montserrat Volcano Observatory