Montserrat Volcano Observatory
Report for the period midday 7 September to midday 14 September 2007
Activity during the reporting period for the Soufrière Hills Volcano (SHV) continued once more to be low. Good dome visibility on 10 September revealed similar morphology to the previous reporting period.
Measurable seismic activity remained very low and the seismic network recording 6 rockfalls and 5 volcano-tectonic earthquakes.
The sulphur dioxide (SO2) flux rate ranged from a maximum of 1083 tonnes per day (t/d) to a minimum of 405 t/d with an average flux rate for the period of 688 t/d continuing a trend which is slightly higher than the long-term average which remains around 550 t/d. Due to unfavourable wind conditions Fourier Transform Infrared (FTIR) measurements were not possible.
The GPS installation at South Soufrière Hill was accessed on 12 September and the data retrieved. This made processing of the baseline network possible. The resultant data indicates that the inflation reported to have started in June is on the wane.
A reminder that whilst lava extrusion has ceased and the dome may not be actively growing, it remains as a large mass of partially molten lava capable of collapsing or exploding, however the likelihood of this decreases with time if no further lava extrusion occurs. The amount of material above Tyres Ghaut to the NW of the dome is sufficient to generate pyroclastic flows and surges capable of impacting on the lower Belham Valley and low lying surrounding areas including lower Happy Hill and the Old Towne ridge.
The alert level remained at 4.
Attention is drawn to the Press Release page of the website.
Residents of Montserrat and visitors to the island are advised to tune into ZJB Radio 88.3 or 95.5 FM for up-to-date information on the volcano.
Access to all areas on the southern flanks of the Belham Valley east of the Belham Bridge and areas south are prohibited as is south of Jack Boy Hill to Bramble airport and beyond . The maritime exclusion zone around the southern part of the island extends 4 km off shore from Spanish Point to Roches Yard on the east side of the volcano, 2 km offshore from O’Garras to Sturge Park on the south-west (previous risk maps are being edited).
For further explanations of the volcanic phenomena described, and information about the Soufrière Hills Volcano and the ongoing eruption, please look at the rest of the MVO website. http://www.mvo.ms.
Mick Strutt
Acting Director
Montserrat Volcano Observatory
P.O. BOX 318
Flemmings
Montserrat
West Indies
Tel: 1-664-491-5647
FAX: 1-664-491-2423
Email: mick@mvo.ms / mhst@bgs.ac.uk
