Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 29 September
to 16:00 30 September 1996

Activity at the Soufriere Hills volcano has been relatively low today, although two series of volcano-tectonic earthquakes occurred in the afternoon and a small ash cloud was observed at the same time. Visibility has been poor, and no views have been possible of the crater area,

The seismic activity was much lower than during the last few days, with 29 volcano-tectonic, 9 hybrid and 8 long-period earthquakes. The most significant events were two intense series of volcano-tectonic earthquakes between 14:27 to 14:47 and 15:04 to 15:06. During the first series, a small rockfall signal occurred, and this was accompanied by an ash cloud that drifted towards Plymouth. Five other small rockfalls were recorded during the period. The lack of large rockfalls suggests that new dome growth is limited to the interior of the dome, probably at the base of the scar feature caused by the explosion of 17 September. All indications are that the rate of dome growth is low, but this will need to be confirmed by visual observations.

Visibility was poor for most of the day, and no views of the dome were obtained. The helicopter was undergoing repairs for most of the day.

EDM measurements were attempted on the O'Garros, Galloways and Chances Peak triangle. The line from Galloways was measured successfully, but no reflection could be obtained from O'Garros. The Chances Peak EDM reflector will need to be visited again, and possibly reoriented. The Galloways - Chances Peak line has lengthened by 13 mm during the last 16 days, a rate that is similar to previous measurements.

Processing has continued on the volume measurements made yesterday in the Tar River valley, and the results will be available soon. Measurements have been made today of the densities of some of the rocks and pumice clasts from the 17 September explosion. Rainwater samples were collected from the Plymouth area, and ash trays were cleaned and replaced.

Work started today in the Observatory to install the computer equipment for the new seismic network. The network will consist of eight new seismic stations which will be installed during the next two weeks.

Further rockfalls and possibly pyroclastic flows could occur during the next few days. Scientists expect that these will be confined to the Tar River valley area. There is still a lot of ash around, and dust masks should be worn if necessary.

Individuals put themselves in extreme danger if they venture beyond the Long Ground area into the Tar River valley. All individuals passing checkpoints in whatever part of the island are reminded that they are entering areas which may become unsafe very quickly, and everyone should be on maximum alert in all of these areas. All residents of southern Montserrat are asked to once again ensure that they are familiar with evacuation procedures.

Montserrat Volcano Observatory