Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 25 October
to 6 pm 26 October 1997

The level of activity at the volcano has remained low during the last 24 hours. The new dome which has been growing since the 22 October has, however, enlarged considerably and has filled approximately half of the explosion crater.

Although it has been cloudy for most of the day, brief glimpses of the new dome inside the explosion crater were obtained. The new dome which is dark grey in colour and blocky was estimated to be a height of approximately 75 to 80 m above the tephra rampart on the open NE crater edge. The new growth is continuing to overspill the crater towards Tuitt's Ghaut and small rockfalls have already been observed going down the top of the ghaut. The rapid growth of the dome indicates that the rate at which new magma is reaching the surface is well above average levels. Preliminary estimates of the extrusion rate are 8 cubic meters per second. During the next few days the MVO will try to carry out a comprehensive survey of the dome . It is likely that pyroclastic flows will occur in the next few days down Tuitts Ghaut.

There were 36 hybrid earthquakes, 69 long period earthquakes, 23 rockfall signals and one volcano tectonic earthquake between 4 pm yesterday and 4 pm today. These earthquakes are probably related to dome growth. The long period events are small ones, but they occur at rates of up to four events per minute, and sometimes almost get into what appears to be tremor episodes. This increase in the frequency of the events seem to have been the same for most of the entire reporting period. Although there have been no explosions for the last 4 days there is still a chance that explosions could happen at any time . It is not safe to live in Friths, Old Towne or Salem.

The ash sampling program continued in the Mongo Hill and Olveston areas today 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. Ghauts leading away from the volcano are especially dangerous because of the possibility of hot mudflows travelling down the valleys after heavy rainfall in higher regions. and to stay tuned to Radio Montserrat for further information.

Montserrat Volcano Observatory