Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 6 October
to 4 pm 7 October 1997

There have been three further explosions in the last 24 hours, including one just after 4 o'clock this afternoon. This brings the total number of explosions since the 22nd of September to 39. There was no change in seismicity before either of the first two explosions but the last explosion was preceded by a hybrid swarm which included some moderately sized earthquakes.

The explosions were at 5:51 yesterday evening, 4:06 this morning and 4:03 this afternoon. The two afternoon explosions were clearly observed and were both followed by pyroclastic flows into the Gages Valley, over the Farrells Plane, into Tuitts Ghaut and into the Tar River Valley. The explosion at 4:06 this morning was not well observed, due to darkness and low cloud cover, but the seismic signal was very similar to that associated with the other explosions of this sequence. Yesterday afternoon the ash column rose to an estimated 18,000 feet and drifted very slowly northeast - a fine dusting of ash fell throughout the island. Ash also fell in occupied areas early this morning. The ash cloud this afternoon was observed to be very steamy and no fallout has been reported, despite the cloud reaching an estimated height of 20,000 feet and blowing in a northeasterly direction. All three explosions were followed by a period of low-frequency tremor.

15 hybrid earthquakes, 6 volcano-tectonic earthquakes, 1 long period earthquake and 8 rockfall signals were recorded over the reporting period. Most of the hybrids and volcano tectonic earthquakes occurred in a swarm which started at 1:11 this afternoon and which is continuing as this report is being written.

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