Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 18 May
to 16:00 19 May 1996

Volcanic activity at the Soufriere Hills volcano during this period continued at the same level as that observed yesterday. Seismicity continues to be dominated by small- to moderate-sized rockfall signals. The largest of these occurred at 23:32 on the 18 May and 09:27, 10:50 and 11:06 on the 19 May. The event of 09:27 generated an ash plume which reportedly reached 4000 ft and was observed from Brambles Airport. The event of 11:06 generated some light ashfall in the upper Gages valley.

There were 5 long-period events and 2 VT earthquakes recorded by the seismic network today. The small hybrid events which appeared on the Chances Peak seismograph yesterday increased in frequency and size from about 03:14 on 19 May. The events attained a maximum frequency of about 2 per minute during the day and by 16:00 had again become very small and less frequent. Variable periods of low amplitude broadband tremor have been recorded on the Gages seismic station since 01:10 this morning. One teleseismic event was recorded by the seismograph network at 23:27 on the 18 May.

Low cloud cover continues to prevent good views of the volcano. Brief glimpses of the lower parts of the dome were possible around noon today. Once again it was not possible to determine whether there were any changes in the structure of the dome; however an area in the vicinity of the Tar River Soufriere was observed to be steaming. This may be related to ignition of sulphur deposits by the pyroclastic flow which occurred on Sunday 12 May.

EDM measurements were made on the western triangle at Windy Hill-Farrells-St Georges Hill. Changes in line lengths on this triangle continue to show no consistent trends. An attempt was made to occupy the eastern triangle but low cloud cover prevented clear views of the reflector. No measurements were made on the MVO GPS network today.

COSPEC measurements were taken today, but the data has not yet been processed.

The present level of activity at the Soufriere Hills Volcano continues to cause concern to the scientists. The MVO urges that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

Montserrat Volcano Observatory