Montserrat Volcano Observatory

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

Fifty five (55) earthquakes have been located during this period. The seismicity continues to be scattered around the volcano, with clusters beneath the Upper Gages area and, unusually, in the Roche's Yard area; most earthquakes were in the depth range 0 to 3.5 km (0 to 2 miles). Two relatively large earthquakes occurred in the Roche's Yard area at 02:38 and 05:35 on 22 Nov, the second of which was reportedly felt across much of the southern part of the island. This earthquake was followed by another at 05:57 in the St George's Hill area which had an estimated magnitude of 3.2 on the Richter Scale and was again felt over much of the southern part of the island.

Due to the low level cloud which covered the flanks of the volcano all day, no EDM measurements were possible today; a clear line of site is required between the measuring instrument and the target for a reading to be made.

GPS (Global Positioning System) surveys continue to be carried out each day. These surveys do not require clear conditions so have been functioning as normal today. Data on the baselines between St George's Hill, Reid's Hill and Tar River showed changes of only a few millimetres for the period between 18 and 19 November Data for the baselines between St George's Hill, Chances Peak and Tar River from the occupation on 21 Nov have been processed today. The line between Chances Peak and Tar River showed a 2.3 cm (1 inch) shortening since 17 Nov; this may indicate some relaxation of the volcano after the intrusive events and the large lengthening of this line in late October and early November. The other two baselines of this set showed movements of less than 1 cm.

No visual observations from the Crater rim were made today because of the low cloud covering the volcano.

Dr Paul Jackson of the Seismic Research Unit (University of the West Indies) arrived back on island today after a brief period away. He will replace Mr Lutchman Pollard in the monitoring team; Mr Pollard departs on 24 November.

Montserrat Volcano Observatory