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Montserrat Volcano Observatory
Report for the period midday 08 September to midday 15 September 2006
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Visual observations show that the dome has continued to grow quickly during the reporting period; growth appears to have occurred on all sides of the dome. The main event during the reporting period has been a significant increase in activity at the vent in the Gages wall. The vent started emitting ash late on Saturday 9 September and venting became more vigorous through Sunday 10 September. By 3pm on Sunday the venting was so vigorous that the vent had widened significantly and small explosions were observed sending black jets up to 100m above the vent. Small fountain collapse pyroclastic flows were observed travelling 1km down the Gages valley. The vigorous activity from this vent has caused partial destruction of the upper part of the Gages wall adjacent to Chances Peak. Explosive activity had stopped by 11 September. The ash venting increased in vigour again late on 14 September and tremor associated with this is ongoing.
This period of increased activity has also been accompanied by high levels of pyroclastic flow activity down the Tar River valley with one pyroclastic flow being confirmed as reaching the sea around 9 pm on Wednesday 13 September.
Seismicity has been dominated by long periods of tremor related to the ash venting. The seismic network recorded 413 rockfall signals, 100 long period rockfall signals, 38 long period earthquakes, 210 hybrid earthquakes and 5 volcano tectonic earthquakes during the reporting period.
Average sulphur dioxide flux for the reporting period was estimated at 405 tonnes/day, varying between 71 tonnes/day on 10 September and 1984 tonnes/day on 11 September.
The alert level remains at 4.
Residents of Montserrat and visitors to the island are advised to tune into ZJB Radio for up-to-date information on the volcano. Access to all areas south of Richmond Hill, and south of Jack Boy Hill to Bramble airport and beyond is prohibited at all times. The daytime entry zone, comprising the top part of St. George's Hill, is closed. The maritime exclusion zone around the southern part of the island extends 3 km off shore from Whites Yard to Roches Yard on the east side of the volcano, 2 km offshore from O'Garras to Gingoes on the south-west, and 200 m offshore from Plymouth.
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 <http://www.mvo.ms/> .
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