Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 17 September
to 4 pm 18 September 1997

The volcano has been moderately active over the last 24 hours with rockfall and pyroclastic flow activity continuing to be concentrated in bursts every 12 hours. The period of enhanced rockfall activity last night was preceded by a sparse hybrid swarm. All of the pyroclastic flows which were observed travelled down Tuitt's ghaut.

Over the reporting period there were 63 rockfall events, 11 long period earthquakes and 14 hybrid earthquakes. There were no volcano-tectonic earthquakes. Most of the hybrids occurred in a hybrid swarm starting at 7.30 yesterday evening, this swarm continued after the pyroclastic flow activity started at 9.0 pm. The pyroclastic flow activity died away at about 1 this morning. The second period of enhanced rockfall activity occurred between 8.30 am and 12.30 am.

Visibility has been poor again today and the dome remained covered by cl oud. Nevertheless, there is no doubt that the dome is still growing rapidly and there is still potential for large pyroclastic flows. Large pyroclastic flows generated on the northern and western sides of the dome are likely to reach the Belham valley. Rapidly moving surges of hot ash associated with such flows could reach areas such as Friths, Old Towne, Salem and Olveston. Such flows and surges could occur with no warning and so people still living in these areas are urged to move north as soon as possible.

In addition to generation of large pyroclastic flows, explosions could also occur. If an explosion occurs, small rocks and ash can fall anywhere on the island. People should seek shelter under a strong roof as soon as possible. Helmets or other head protection should be used and it should be remembered that ash and falling rocks make driving hazardous.

Montserrat Volcano Observatory