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- Assessment of Harards & Risks Associated with Soufriere Hills Volcanco, Montserrat July 19 2007
Assessment of Harards & Risks Associated with Soufriere Hills Volcanco, Montserrat July 19 2007
- By S Coward
- Published 27-Jul-07
- Hurricanes/Natural Disasters
- Unrated
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No visual changes to dome sructure since mid March
July 27, 2007 -- This report responds to a request from the Government of Montserrat Emergency Planning Group (EPG) via Mark Twigg on 14 June 2007 for a re- reevaluation of the current volcanic risks on Montserrat.
Since the last SAC report of 16 April 2007 (SAC 8), there has been no resumption of lava extrusion at Soufrière Hills Volcano. This may well indicate that we are now moving into a major pause in surface activity, the third since the start of the eruption. Given the high risk levels assessed in March-April, it is felt that a re- reevaluation now is warranted.
Evaluation State of Volcanic Activity
The next paragraph is MVO’s summary (of 18 June 2007) of recent activity followed by plots of the seismic event counts and the SO 2 emission rate since 1 April 2007, and the GPS (MVO1-SOUF line length) plot since 1 Jan. 2006 (Fig.1):
1. “Rockfall activity declined markedly !from mid March, and it appears dome growth ceased in early April. There have been no visual changes to the dome structure since. The dome volume has been estimated (from photgrametric methods) to be
208Mm. We carried out Lidar scan from Galways just over a week ago, but this data have yet to be processed. All other measurable activity has remained low. See combi- combiplot plot attached. GPS data !are not included, but has been essentially flat. This trend is confirmed by EDM measurements. No change to line lengths. Pyroclastic activity has been at low level but ongoing, predominantly affecting the east and northeast with occasional flows in Tar river, Tuitts Ghaut and at the top of Farrell's plain. A few small flows have also been observed !in Tyres Ghaut. Fresh deposits have also been observed on the southern side of the dome.
The largest pyroclastic flows of recent months occurred after a period of heavy rain early on Monday morning in the Tar River valley. Fresh deposits !have also been !observed on the Tar River fan, but stopping short of the sea. Fumarolic activity is presently observed around the scar from the 08 January collapse where it is currently most vigorous. It can also be observed high on the south eastern side of the dome. The vent behind Gages Wall remains active, and emissions here remain distinctly blue suggesting SO2 venting.”
DOWNLOAD FULL REPORT BELOW
Source: mvo.ms
Since the last SAC report of 16 April 2007 (SAC 8), there has been no resumption of lava extrusion at Soufrière Hills Volcano. This may well indicate that we are now moving into a major pause in surface activity, the third since the start of the eruption. Given the high risk levels assessed in March-April, it is felt that a re- reevaluation now is warranted.
Evaluation State of Volcanic Activity
The next paragraph is MVO’s summary (of 18 June 2007) of recent activity followed by plots of the seismic event counts and the SO 2 emission rate since 1 April 2007, and the GPS (MVO1-SOUF line length) plot since 1 Jan. 2006 (Fig.1):
1. “Rockfall activity declined markedly !from mid March, and it appears dome growth ceased in early April. There have been no visual changes to the dome structure since. The dome volume has been estimated (from photgrametric methods) to be
The largest pyroclastic flows of recent months occurred after a period of heavy rain early on Monday morning in the Tar River valley. Fresh deposits !have also been !observed on the Tar River fan, but stopping short of the sea. Fumarolic activity is presently observed around the scar from the 08 January collapse where it is currently most vigorous. It can also be observed high on the south eastern side of the dome. The vent behind Gages Wall remains active, and emissions here remain distinctly blue suggesting SO2 venting.”
DOWNLOAD FULL REPORT BELOW
Source: mvo.ms
