Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 5 October
to 4 pm 6 October 1997

Three further explosions have occurred at the Soufriere Hills volcano in this reporting period. The total number of explosions in this sequence is now 37. Seismicity apart from the explosions remains at a low level.

The first explosion occurred at 6:42 pm yesterday evening (October 5) and sent pyroclastic flows into the Gages Valley, White River and over the northern flank of the volcano into Tuitts Ghaut. The ash column rose to an estimated 20,000 feet (6000 metres or 6km) in altitude and was then carried toward the west. Light ashfall was reported in Old Towne and Olveston.

The second explosion occurred at 2:44 am this morning (October 6). This event produced a wide ash column which rose to over 15,000 feet (4500 metres or 4.5km) above sea level which was carried toward the west and north-west by light winds. The ash from this event was still visible off the west coast of Montserrat at day-break this morning. There were been no reports of ashfall from this event but it is likely, given the direction in which the cloud moved, that parts of western Montserrat received ash.

The third explosion occurred at 10:43 am this morning sending pyroclastic flows into Gages Valley, Tuitt's Ghaut, White River and Tar River. The eruption column rose quickly to approximately 25,000 feet (7600 metres or 7.6km) above sea level and was then blown toward the north over Montserrat. Fall-out occurred over much of Montserrat from the co-ignimbrite ash plumes (ash formed above pyroclastic flows) and the main eruption column itself.

All three explosions were followed with a period of low-frequency tremor associated with roaring and vigorous ash and steam venting from the summit crater in the dome. Roaring was confirmed from Old Towne following the first event at 6:42 pm. Low level tremor continued following the event at 2:44 am. This was detected only by the seismic stations closest to the volcano.

11 hybrids earthquakes, 2 long period earthquakes and 13 rockfall signals triggered the short-period seismic network over the reporting period. There was also one regional tectonic earthquake which was located north of Montserrat. The dome was very clear today but there have been no major changes to it over the last few days.

Further explosions must be expected and these are most likely to stay similar in size to those experienced already. However, due to the fact that there are no precursor signals to these explosions, MVO are concerned that bigger or longer explosions could occur without warning. These could shed pyroclastic flows far down the Belham Valley, threatening areas in Frith, Old Towne and Salem. All residents still remaining in these areas are thus urged to move out as soon as possible.

After explosions, fallout may occur anywhere on the island, so hard hats or other suitable protection should be worn. Preferably, people should shelter in a sturdy building and wait for the fallout to end. The pumice and coarse ash deposited over the previous few days continues to make many roads very treacherous. 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