Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 21 September
to 4 pm 22 September 1997

Volcanic activity in the last 24 hours has again been at a high level. Within the reporting period there were two explosive eruptions followed by pyroclastic flows. The explosions were smaller than those which occurred at the beginning of August.

The first explosion was at 0055. The direction of subsequent pyroclastic flows is thought to be mainly to the east. The second explosion was at 1046. Pyroclastic flows travelled down the northern and eastern flanks of the volcano. Considerable new deposits were observed in Tyers ghaut and reached Dyers bridge to the north-west. Flows also travelled north east as far as Farms. Vigorously convecting pulses of ash venting were observed for the ? hour following the event, occurring every 10-20 seconds. Audible bangs and rumbles were heard as far north as St. Peters.

Over the last 24 hours 82 hybrid earthquakes, 10 long-period earthquakes, one of which triggered a rockfall, 5 volcano-tectonic earthquakes and 24 rockfalls triggered the seismic network. The second of the explosions was preceded by a swarm of hybrid earthquakes. The swarm started at 0805 and continued until around 1300, containing 45 events. Again, several very large events were recorded.

The potential for further explosions seems high and a period of explosive activity similar to that experienced during August could happen again. As Tyers ghaut fills pyroclastic flows will be able to enter the Belham valley more easily, with successive flows travelling further. An event directed down the Belham valley of a similar size to the one on Sunday morning which destroyed the airport would reach the Belham bridge and impact upon Friths and Salem. All those remaining in the exclusion zone are urged to leave as soon as possible.

Montserrat Volcano Observatory