Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 on 21 December
to 16:00 on 22 December 1995

Three (3) earthquakes have been located during this period, scattered to the north-east of the volcano at depths of 0 to 6 km. A total of 18 long-period earthquakes were also recorded on most of the seismometers, but these could not be located. Small long-period earthquakes were recorded at the Gages seismic station. These were more frequent after 18:00 last night, but the rate has now reduced to about one per minute. A regional earthquake was recorded at 01:30. This was of magnitude 3,5 and was located 25 km north-east of Montserrat.

Measurement of the Castle Peak EDM lines were made this morning and no changes were detected. GPS measurements were again made at St George's Hill, Reid's Hill and Harris' Lookout. However, the results will not be processed until the end of the month.

Visual observations were made from various points around the volcano and from the helicopter today, with excellent viewing conditions. The large spine in the central part of the new lava dome has grown only slightly, in contrast to the rapid growth seen earlier in the week. This spine has now been joined by two smaller spines, one of which grew 7 m (20 ft) overnight. Several ash eruptions have been seen throughout the day. The largest eruption occurred at 10:58 from a point near to the new spine, and produced an ash cloud up to about 5000 ft. Ash was blown northwards over much of the island. The ash eruptions have been more vigourous than those observed over the last few days, and the clouds have been convecting suggesting the presence of some hot material.

Dr Ellen Howell left the island this morning. She has been operating the GPS instruments for the last two weeks.

Montserrat Volcano Observatory