Montserrat Volcano Observatory


Daily Report
Report for the period 16:00 on 26 Feb. 1996
to 16:00 on 27 Feb. 1996


Seismicity for the period under review continued with long period earthquakes occurring at the rate of about three per hour, of magnitude between 1.0 and 1.5 and at depths ranging from 0.5 to 3.0 km beneath the crater area. Intermittent episodes of low to moderate broadband tremor were recorded at the seismograph station at Gages from 23:00 on 26 February to 08:20 on 27 February. After a grace period of four hours, broadband tremor recommenced but at a slightly higher level than before and continued at this level until the end of the review period. Rock falls and small eruptions signals resulting from dome growth were recorded, on the Gages and Chances Peak seismograph stations . The most prominent signal of this type occurred at 12:36 on 27 February and produced a small ash cloud which was clearly visible from the Observatory.

EDM measurements were made today between Long Ground, White's Yard and Castle Peak sites . Measurements were also made at lines between Amersham and Gages. Changes in distances along these lines were minimal. Lines between Dagen ham and Gages showed a shortening of 14 millimeters since 14 January.

Visual observations were made this afternoon from Chances Peak and from the nothern side of the dome. On arrival at Chances Peak the viewing conditions were excellent. Various sources emitting mixtures of gases, steam and ash in generous quantities could be seen. Several moderate sized rockfalls could be seen from the west to southwest sector of the dome. As the afternoon progressed the conditions for viewing worsened due to more frequent rockfalls and increased venting. A team of volcanic gas experts also visited Gages and Galways soufrieres to take gas and water samples. They also took samples and temperatures of substances on the lava dome. Analysis of these substances will provide more information about the blanket of emitted substances that have been settling along the slopes of the western flanks of the volcano in recent weeks.


Montserrat Volcano Observatory