MVO report for the period midday 5th October to midday 12th October, 2007
By MVO
Fri, 12 Oct 2007, 11:24
Montserrat Volcano Observatory
Report for the period 05 September to 12 September 2007
Visual observations during the period revealed shown no changes to the dome structure and the pause in lava extrusion [and dome growth] continues. Nevertheless, 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, although the likelihood of this is thought to decrease with time as no further lava extrusion occurs.
The smell of sulphur gases has at times been very strong in the north of Montserrat during the period, this was due to the prevailing wind direction carrying the emission plume northwards as opposed to any change in volcanic activity.
Recorded seismic activity remained very low throughout the period and the seismic network recorded just 10 rockfall signals.
The recorded sulphur dioxide (SO2) flux rate showed an uneven increase during the period, from a minimum of 259 tonnes per day (t/d) at the beginning to a maximum of 687 t/d at the end. This gives an average flux rate for the period of 508 t/d, in line with the long-term average for the eruption.
Fourier Transform Infrared (FTIR) measurements on 08 and 09 October gave an average hydrogen chloride to sulphur dioxide (HCL:SO2) ratio of 0.38, in line with recent measurements and previous periods when there was no active dome growth.
The alert level remained at 4.
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 (readers are referred to the updated risk map, available on the MVO website).
Additionally for further explanations of the volcanic phenomena described, and information about the Soufrière Hills Volcano and the ongoing eruption, please look at the MVO website: http://www.mvo.ms.
Vicky Hards
Director
Montserrat Volcano Observatory
P.O. BOX 318
Flemmings
Montserrat
West Indies
Tel: 1-664-491-5647
FAX: 1-664-491-2423
Email: vicky@mvo.ms