Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 4 October
to 7 am 5 October 1997

Two further explosions happened at the Soufriere Hills volcano in this reporting period. Thus the lull in explosive activity which occurred prior to yesterday morning's explosion was only temporary, and further explosions must be expected.

Both explosions were rather similar in their size and style. Quite dilute eruption columns rose at 6:27 last evening and at 2:53 this morning after clear long-period explosive signals recorded on the seismic network. A BWIA pilot in the area gave a column height of 38,000 feet for last night's event. Due to very light winds, the ash plume moved only very slowly on both occasions and no ash or pumice fall was reported for either event. Pyroclastic flows associated with these events could not be clearly seen, although flows certainly went in to Gages valley and Tuitt's Ghaut and may well have gone in other directions also. An observations flight this morning will confirm this and also check on the state of the dome and crater area.

Seismicity apart from the explosions remains at a very low level, with no precursors to explosions whatsoever. In fact, between the two explosions reported here, just one hybrid earthquake occurred. Both 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.

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