Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 20 September
to 4 pm 21 September 1997

At 3:54 this morning a large pyroclastic flow came down Tuitts' Ghaut and covered an area of 3 square km in the East of the island. Seismicity has been at a moderately high level, with hybrid earthquakes occurring both before and after the flow.

A low intensity hybrid swarm began at 9 last night and continued until midnight, when a period of increased rockfall activity began. The rockfall activity continued until the pyroclastic flow started at 3:54 am. The flow lasted over 20 minutes and covered the area from Whites Yard in the South to the airport in the North. It entered the sea at many places, creating small deltas at the ends of Whites Ghaut and Pea Ghaut. The airport buildings were set on fire and any buildings remaining in Bethel were destroyed. Tuitts' and Spanish Point were also devastated. Starting immediately after the flow several hybrid earthquakes have been recorded each hour - this activity continues at the time of writing.

Over the last 24 hours 109 hybrid earthquakes, 6 long-period earthquakes, one of which triggered a rockfall and 50 rockfalls triggered the seismic network.

Although the dome has not been seen today it is unlikely that the flow this morning reduced the mass of dome material above Gages and Mosquito Ghaut. Thus the chances of large pyroclastic flows to the North and West remain relatively high. Flows in either of these directions are likely to enter the Belham Valley and the surge associated with such flows could reach Frith, Old Towne, Olveston and Salem. Anyone still in these areas should move North as soon as they can.

In addition to large pyroclastic flows, explosions may 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 and helmets or other head protection should be worn.

Montserrat Volcano Observatory