Montserrat Volcano Observatory

Daily Report
Report from 16:00 on 4 April
to 16:00 on 5 April 1996

The seismic activity during the period under report has remained moderately elevated at levels similar to the last few days, dominated by the occurrence of small hybrid type events from within the crater region. These events are interpreted as indicating continuing dome growth.

During the night hours, several seismic signals were interpreted as rockfalls off the eastern dome. Two larger events occurred at 20:24 and 22:23 on 4 April, possibly the result of small explosions in the crater. However, low cloud over the crater prevented confirmation of ash plumes from these events. With daylight, some rockfalls were observed from Bramble Airport to have small convecting ash clouds associated with them. A moderately strong explosive ash eruption took place at about 12:53 local time, producing a cloud which rose to about 5000 feet and a small pyroclastic flow into the Tar River valley.

Visibility of the volcano from the Observatory remained poor but an inspection from the ground at Long Ground revealed that the most recent spine is still intact: at mid-morning, its height was measured at 2716 feet asl (828m), i.e. 35 m above the top level of the dome.

The eastern EDM triangle was re-occupied on 5 April: the raw data indicate no significant changes on these lines.

A (still hot) sample of Wednesday's pyroclastic flow (3 March) was collected from the Tar River by Dr. Simon Young and Angus Miller.

During a helicopter inspection of the crater at 13:30, small rock falls were observed to be occurring almost continuously, and there were areas of vigorous steaming on top parts of the dome. There was no sign of change in the western parts of the dome, including that abutting the crater under Gage's Wall.

The MVO still considers the volcano to be in an elevated and dangerous state of activity and hence all recommended precautions should be strictly adhered to.

Dr. Willy Aspinall returned to Montserrat on 30 March from the UK; Mr. Lloyd Lynch left MVO on 31 March to go back to the SRU in Trinidad; Dr. Paul Jackson (SRU) rejoined the MVO team on 1 April, and Dr. John Shepherd (Lancaster University) arrived in Montserrat on 4 April, bringing a new state-of-the-art GPS surveying system to support deformation measurements on the volcano.

Montserrat Volcano Observatory