Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 4 January
to 16:00 5 January 1997
The current alert level is ORANGE

Growth of the October 1 dome continues to generate rockfalls and small pyroclastic flows, although at a slightly reduced rate. Areas outside of the Tar River valley are not threatened by this activity, although anywhere downwind of the volcano will be affected by light ashfall. A rapid escalation in activity is possible and could have serious consequences for much of the evacuated areas. Everyone should remain vigilant and follow the alert procedures. There is no access to zone A/B and only limited access to zone C/D.

Visibility has been good for much of the day. During a helicopter flight this morning, there appeared to be continuous ash production from the top and flanks of the dome, not all of it from rockfalls. Rockfall activity was high and there were small pyroclastic flows every 2 or 3 minutes. Observations have been possible during most of the rest of the day. Rockfall activity continued from much of the eastern face of the dome. However the level of activity was slightly less than during the last period of good visibility two days ago.

Almost all of the rockfalls and flows were channelled down the erosion chute over the top of Castle Peak. None of these flows travelled more than a few hundred metres from the base of the dome. There was some activity on the north-east flank of the dome and a few rockfalls down the northern flank towards Farrell's wall. Material is accumulating very slowly against Farrell's wall, but there is only about 20 ft left before it is overtopped at its lowest point, Tuitt's Ghaut.

Seismic activity was dominated by rockfalls. 38 rockfall signals were recorded today, less than half the number recorded yesterday. There was very little in the way of other types of seismic activity, with three long-period, five hybrid and one VT earthquake recorded.

EDM measurements were made on stations in the Northern triangle. This data has not yet been processed.

Photographs were taken from the three fixed locations around the volcano to record the amount of dome growth.

Theodolite measurements of the locations of points on the dome show that the height of the dome has remained relatively constant, at about 2,900 ft, since 1 January. The new lobe of lava at the top of the dome is about 150 ft thick.

Gravity stations along the line on the northern flank of the volcano were remeasured today.

Angus Miller returned to Montserrat this morning after a short break in the UK.

Montserrat Volcano Observatory