Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 9 October
to 7 am 10 October 1997

Another explosion occurred overnight, this took place at 4:13 this morning. The ash column from this event rapidly reached at least 20,000ft and was blown to the north-east. Pyroclastic flows generated during this explosion travelled down Tuitt's Ghaut, Farrell's plain and Gages Valley. Observers located at Jack boy hill reported that pyroclastic flows travelling down the north eastern flank of the volcano nearly reached to the sea. As usual the explosion was followed by a period of tremor, which lasted for approximately 1.5 hours and was associated with ash and steam venting. A large, although diffuse, ash cloud is currently sitting above the central part of the island and fallout of ash may occur in inhabited regions.

The level of seismic activity before and after the explosion was low and dominated by small rockfall events. A few small long period earthquakes and a hybrid earthquake were also recorded. A few hybrid events also occurred just following the explosion.

Further explosions are expected and, although these will probably be similar in size to those experienced already, longer explosions fuelling more vigorous pyroclastic flows are a distinct possibility. There has been little seismic activity before the last few explosions and no warning is expected before further events. All residents remaining in Frith, Old Towne and Salem are thus urged to move out as soon as possible.

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 this is not possible then hard hats or other suitable protection should be worn. Avoid driving during or immediately after ashfall if at all possible. Although much of the pumice and coarse ash deposited on roads over the previous few days has been removed by rain there are still patches of ash 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