Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 on 21 Feb. 1996
to 16:00 on 22 Feb. 1996

Seismicity during the past 24 hours has been of a variable nature, with a total of 7 earthquakes located. All were in the depth range 0 to 3 km, all but one being beneath the volcano. The other one was an event beneath Long Ground at 05:47 on 22 February. Three of these events gave a good volcano-tectonic signature whilst the others were of the long-period type. The broadband tremor which was occurring for most of the last reporting period died out at about 19:30 on 21 February. Small, repetitive events started to appear on the Gages and Chances Peak seismographs soon after the end of the broadband signal and have continued throughout the period under review; they are currently at their highest rate so far at one every 90 seconds or so. Past experience suggests that these events will increase in frequency and amplitude over the next few days and may be accompanied by some increase in dome growth rate. Seismic signals associated with rock fall events have been recorded on the Gages and Chances Peak throughout the period, with the largest occurring at 20:10 on 21 February; no ash fall was reported after this event.

Low cloud cover prevented EDM measurements for most of the day, although the triangle between St George's Hill, Windy Hill and Farrell's was measured late in the afternoon of 22 February; the results are not yet available. Work continues on preparation of a leveling line in the Upper Amersham area which will enable further measurements to be made in order to understand better any deformation taking place on the volcano.

Visual observations were attempted from the helicopter this afternoon, 22 February, but low cloud cover prevented any sightings of the new dome. Clear conditions during the evening of 21 February enabled good views of the new dome above and behind the top of the Gages Wall from the northern parts of Plymouth, Richmond Hill and Foxes Bay. General glowing and individual rock falls could be seen, but all material is still contained within English's Crater.

Drs Alan Smith and John Roobol left the island today after a week of research work on the older deposits of the Soufriere Hills volcano as exposed along the southern coastline of Montserrat; these deposits give scientists a window into the past behaviour of the volcano which is very useful in monitoring the current activity. Mr Lloyd Lynch arrived back on island today after several months at his normal post in Trinidad. Mr Lynch will take over as acting Chief Scientist after the departure of Mr Richard Robertson tomorrow.

Montserrat Volcano Observatory