Montserrat Volcano Observatory

Morning Report
Report for the period 16:00 17 March
to 07:00 18 March 1997
The current alert level is AMBER

The earthquake swarm that started yesterday morning is still continuing but at a reduced intensity. Further signals have been recorded which are reminiscent of the type caused by pyroclastic flows over the Galway's Wall, triggered by an earthquake. Rockfall signals have occurred intermittently throughout the reporting period. Low amplitude tremor on the Gages seismic station died away from about 10:pm last night. The seismicity indicates that the dome continues to grow.

Low cloud on the top of the volcano is currently hampering views of the dome and crater, although the cloud is clearing and good views may be possible later in the day. An observation flight yesterday evening allowed closer examination of the deposits in the Galway's area. Pyroclastic flow deposits are reaching about a kilometres from the crater wall. No burning of vegetation was observed suggesting that relatively cool material is involved, most likely from the pre- September 17 dome. Fresh pyroclastic flow deposits were also seen in the southern half of the Tar River Valley coming from the southern section of the dome.

The scientific team at the Montserrat Volcano Observatory would like to re-iterate the following points. The volcano remains active and potentially dangerous. The lava dome is currently larger than ever before. There are several areas on the eastern and south eastern face which appear very unstable and further pyroclastic flows are likely. It also seems likely that there will be further pyroclastic flows from the dome above Galway's Wall, especially if an earthquake swarm occurs. Explosive activity similar to the September 17 event and possibly larger is still a distinct possibility. People entering zone C must remain alert, listen to Radio Montserrat and be ready to leave at short notice. Only essential visits should be made. The ash levels in Plymouth are hazardous, and it is extremely important to wear an ash mask when there is ash in the air.

All at MVO would like to wish everybody a very happy St. Patrick's Day.

Montserrat Volcano Observatory