Montserrat Volcano Observatory

Evening Report
Report for the period 16:00 on 07 December to
16:00 on 08 December 1995

Six (6) earthquakes were located during the period. These all occurred beneath the Soufriere Hills volcano at depths of 0 to 2.5 km (0 to 1.5 miles). The level of seismicity has decreased since 05:00 this morning. The background tremor recorded over the past few days has completely subsided. However individual long-period events continue to be recorded at a rate of about 2 per minute on the Gages, Long Ground and Bethel seismometers. A mudflow signal was recorded by the Gages seismograph station at approximately1:15pm today. Visual observation of this flow were made by scientists conducting EDM measurements in the Amersham area.

Poor visibility prevented measurement of the EDM line at Gages. However, permanent markers were put in at Amersham and Dagenham for use as station sites for the EDM instrument. Measurement of the Long Ground-Whites-Castle EDM triangle is currently being conducted. The results for these will be available tomorrow. GPS measurements were again made overnight at stations at Harris' Lookout, Radio Antilles Aerial and St. George's Hill. The results from these measurements as well as the new line at Roche's Yard are currently being processed.

Visual observations of the crater area were made today from the air and from the Long Ground-Whites area. The most prominent part of the dome which is currently growing in the July 18th vent has broken along the large cracks which were noted during previous helicopter flights. Deformation of the areas around the July 18th and Sept. 25th dome continues. A small ash cloud was observed by scientists during the helicopter flight. This event was probably associated with a large long-period event which occurred at 10:25.

Dr William Ambeh, Head of the Seismic Research Unit, rejoined the MVO team today. Dr Ambeh will take over as Chief Scientist from Mr Lloyd Lynch who is scheduled to leave for Trinidad tomorrow. Professor Alan Smith of the University of Puerto Rico left the island today. Professor Smith assisted with measurement of the GPS lines while he was on the island and also with interpretation of volcanological aspects of the current crisis.

Montserrat Volcano Observatory