Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 22 October
to 6 pm 23 October 1997

The level of activity at the volcano has been low during the reporting period. There have been no explosions but a small new dome has begun to grow just inside the open side of the crater. This suggests that at the present time magma inside the volcano is able to lose its gas more easily and can reach the surface without exploding. The crater has been steaming almost continuously all day and fumaroles on the eastern side of the dome have also been steaming vigorously. The small new dome is blocky and dark in colour and just overlaps the open north eastern lip of the crater.

The presence of a small dome does not necessarily mean that there will be no further explosions, an explosion could still occur with little or no warning at any time. At 6pm this evening it was 47 hours since the last explosion, this is the longest gap that we have had in the present sequence.

A swarm of mainly volcano-tectonic earthquakes which began on the evening of 21 October ended last night in the early hours of the morning. Since then seismic activity has been low with occasional earthquakes and rockfall signals. Between 4pm yesterday and 4pm today there have been 16 vt earthquakes, 16 long period earthquakes, 7 hybrid earthquakes and 15 rockfall events. The long period events which are all small have mostly occurred since yesterday afternoon and are thought to be related to ash and steam venting. A small pyroclastic flow travelled about 1km down Tuitt's Ghaut at 1.30pm this afternoon generating a small ash cloud.

Recent explosions have sent pyroclastic flows into Plymouth, into the upper part of the Belham Valley and to the sea in the Tar and White rivers, and future flows, especially those generated by gravitational collapse of the dome, are likely to travel further still. Mudflows are likely to occur in the ghauts after heavy rain. These mudflows could be hot and it is extremely dangerous to be in any ghauts in the southern part of Montserrat at the moment.

The ash sampling program continues and the results today indicate that the levels are low. However, there is still a significant amount of ash around on roads, which is easily lifted into the air by traffic. Cleaning also lifts a lot of dust so people are urged to wear their masks if they are engaged in these activities.

All residents of Montserrat are reminded to be vigilant, to avoid entering the evacuated zone and to stay tuned to Radio Montserrat for further information.

Montserrat Volcano Observatory