Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 17 May
to 16:00 18 May 1996

Activity at the Soufriere Hills Volcano continued at about the same level as yesterday. Seismicity is still dominated by small- to moderate-sized rockfalls. The largest of these was at 09:25 on 18 May. There were no reports of ashfall from this or any other rockfall. There were 10 long-period events, 5 hybrid events and no VT earthquakes. The sustained period of low-amplitude broadband tremor recorded on the Gages seismic station since 08:17 on 17 May reduced in amplitude overnight and had stopped by 03:30 on 18 May. There was one regional earthquake, at about 03:07 on 18 May.

Cloud continues to obscure the volcano for most of the time. Glimpses of the lower parts of the dome were possible late yesterday afternoon and around noon today. It was not possible to make out any changes in the structure of the dome.

No EDM measurements were possible because of the low cloud cover. Processing of data from the MVO GPS network was carried out today and no further measurements were made.

The University of Puerto Rico GPS experiment was concluded today. Data was collected from the Roches, Harris' Lookout, Reid's Hill and St. Georges Hill sites. Data from this experiment shows only small deformation of the volcano, consistent with both the MVO GPS and EDM measurements. Additional processing of the data will be carried out in Puerto Rico.

The COSPEC data from yesterday has now been processed. The mean SO2 flux was around 130 tonnes per day, consistent with the low estimates obtained since the COSPEC programme was restarted last month. Further measurements were taken today, but that data has not yet been processed. Gas measurements with the FTIR technique are being thwarted by the lack of visibility.

Professors Geoff Wadge of Reading University and Andy Woods of Bristol University arrived on Montserrat yesterday. They will be on the island for about a week to start a project constructing a mathematical model of the Soufriere Hills Volcano. Geoff Wadge is, of course, well known for his work on hazard assesment and will spend some of his time here discussing present, and future, hazards from the volcano. Dr Michael Nolan from the University of Puerto Rico also arrived yesterday to help finish the GPS project. Dr Peter Francis left this afternoon.

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