Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 7 October
to 4 pm 8 October 1997

There have been three further explosions in the last 24 hours, including the one mentioned in last nights Evening report. This brings the total number of explosions since the 22nd of September to 42. Hybrid and long-period earthquake activity occurred before the first and third explosion.

The explosions were at 4:03 pm yesterday evening (October 7), 3:48 am this morning and 3:10 pm this afternoon (October 8). Pyroclastic flows from the first and third explosions were observed travelling down Tuitts Ghaut almost to the sea yesterday evening and as far as Harris this afternoon, Tar River onto the fan, Gages Valley as far as St. George's Hill and out onto the Amersham plain. Darkness prevented any estimate of run-out distance for the pyroclastic flows generated by the event at 3:48 am this morning. Ash columns from these events have reached altitudes in excess of 20,000 feet (6000 metres or 6 km) which have been blown toward the north-east by upper level winds. The columns have been very light in colour suggesting that they are steam-rich. Only light ashfall has been recorded from these events in western and north-western Montserrat as a result of the co-ignimbrite ash clouds (ash from the pyroclastic flows) being carried westward by low level winds.

66 hybrid earthquakes, 10 volcano-tectonic earthquakes, 12 long period earthquake and 6 rockfall signals were recorded over the reporting period. The hybrids earthquakes occurred in two periods: an extended period overnight up to the explosion at 3:48 am this morning and between midday today and the explosion at 3:10 pm this afternoon. The long-period earthquakes occurred mainly before the explosion at 3:10 pm this afternoon. There was also a burst of tremor at around midnight which coincided with audible roaring from the volcano. This is considered to be related to increased venting from the volcano.

Further explosions must be expected and there is a possibility that these will last longer than those already experienced. A longer lasting explosion would produce more material and so be followed by pyroclastic flows which would reach further. Such a longer lasting explosion could look exactly like those already seen as it started and so no useful warnings could be given. All residents still remaining in Frith, Old Towne and Salem are thus urged to move out as soon as possible.

After explosions, fallout can occur anywhere on the island and hard hats or other suitable protection should be worn if you have to be outside. The pumice and coarse ash deposited over the previous few days continues to make 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