Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 10 December
to 6 pm 11 December 1997

After yesterday's slight fluctuation, seismicity has today reverted to the pattern which has existed for some weeks, with rockfall signals being the dominant activity on the volcano. Visibility has again been generally poor and no good views of the dome were obtained today.

Between 16:00 yesterday and 16:00 today, the broadband seismic network recorded 139 rockfall signals, 26 long period and 13 hybrid earthquakes. This activity is still consistent with continuing dome growth.

The main active growth area is still concentrated high up on the Galways sector of the dome, and diffuse ash clouds have been produced throughout the day from the rockfalls.

Although activity is still mainly focused on the southern side of the volcano, past experience as well as recent observations shows that the area of growth on the dome can change very quickly. Growth activity appears now to be backing up behind the major build-up of material in Galways, and rockfalls or pyroclastic flows starting to occur down Gages or Tar River in the near future would not be a surprise.

Montserrat Volcano Observatory