Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 1 October
to 4 pm 2 October 1997

There have again been three explosions over the last 24 hours, each followed by energetic pyroclastic flows down all flanks of the volcano. Eruption columns reached 20 to 40,000 feet and ash was distributed over various areas of Montserrat.

Explosions occurred at 5:41 yesterday afternoon, at 1:05 this morning and at 12:54 this afternoon. Each explosion produced pyroclastic flows in most of the ghauts around the volcano. Over the past 24 hours, flows of hot pumice and ash have reached the sea at the edge of the Tar River delta, to Farms down Tuitt's Ghaut, to Dyer's in Tyer's Ghaut, to Upper George Street in Plymouth and to the sea in White River. Considerable material is being deposited on the upper flanks of the volcano during this activity, enabling each subsequent flow to travel further.

Fallout from these explosions has been distributed by variable winds over many areas of Montserrat. The event late yesterday afternoon distributed ash and pumice westwards and no fallout was reported for inhabited areas of Montserrat. The event early this morning produced considerable ash fallout over much of western and northern Montserrat, and pumice clasts also fell over much of Montserrat. Ash and pumices from the event at lunchtime today were distributed to the east and northeast, with light ash fallout in parts of the north and all down the east coast. Maximum pumice size in inhabited areas for these events was 2 cm (just less than one inch).

The ash column from the 12:54 event today rose to 40,000 feet as reported by a pilot in the area - the other eruption columns were somewhat lower than this. Ash was reported to be falling lightly at V C Bird International Airport late this afternoon.

Apart from the explosions, the last 24 hours have again been relatively quiet seismically. 19 hybrids, 11 volcano-tectonic earthquakes and 8 rockfall signals triggered the seismic network. Post-explosion tremor lasted for less than an hour following the first two explosions in this period, but for nearly 2 hours following the last one. This tremor was associated as usual with vigorous ash and steam venting and roaring noises from the volcano. There are at present no seismic precursors to explosions and earthquake swarms between events are very poorly developed.

The chances of more explosions are very high and these could be larger than anything seen so far. The resulting pyroclastic flows could very easily reach the Belham valley and surges could travel up the valley sides for a considerable distance. All those remaining in the exclusion zone are urged to leave. If the sirens sound in this area at any time, people should move north immediately.

After an explosion fallout can occur anywhere on the island. People should shelter in a strong building and wait for the fallout to end. If you do have to move about then head protection should be worn. Falling ash and pumice reduces visibility and makes driving conditions extremely hazardous. Roads remain difficult and plenty of time should be allowed for any journey and drivers should be very careful. The wearing of ash masks is recommended at all times. Everyone is advised to keep listening to Radio Montserrat for information on the activity.

Montserrat Volcano Observatory