Eighth Meeting of the Scientific Advisory Committee, Montserrat, 20-22 March 2007
http://www.caribbeanpressreleases.com/articles/1512/1/Eighth-Meeting-of-the-Scientific-Advisory-Committee-Montserrat--20-22-March-2007/Page1.html
S Coward
By S Coward
Published on 26-Mar-07
Brades, Montserrat -- March 26, 2007 --- (Preliminary Statement): The
lava dome has continued to grow at a high rate, as it has since the 20 May 2006
collapse. It now has a volume of over 200 million cubic metres and a summit
elevation greater than 1050 metres above sea level.
Eighth Meeting of the Scientific Advisory Committee 20-22 March 2007
Brades, Montserrat -- March 26, 2007 -- (Preliminary report): The
lava dome has continued to grow at a high rate, as it has since the 20 May 2006
collapse. It now has a volume of over 200 million cubic metres and a summit
elevation greater than 1050 metres above sea level.
Although this is not yet as large as the dome was prior to the 12 July 2003 collapse, the rate of growth towards that size is about three times faster than in 2003. Over the next year we regard a major collapse of the dome down the Tar River Valley to be the most likely outcome, such a collapse would be accompanied by a major ashfall.
However, we regard a pyroclastic flow/surge reaching the lower Belham Valley to be more likely than six months ago. There are two main ways in which this could occur: from a “normal” collapse of a part of the dome down Tyre’s Ghaut and into the Belham Valley, and from a lateral blast (a sideways explosion) to the north or west, as happened to the southwest on Boxing Day 1997.
The volume of the dome that could collapse down the Belham Valley could be as great as 20 million cubic metres or even more in future if the dome continues to grow. The possibility of a lateral blast has increased because of several factors: the rate of growth of the dome, the preferential growth on the northwestern side of dome and the likely pressurization of the dome interior. Such a blast could be triggered by exposing the hot, pressurized interior of the dome, either from a large “normal” collapse or from failure of the crater wall. The likelihood of such a lateral blast-derived pyroclastic flow in the lower Belham Valley is less than the equivalent “normal” collapse-derived flow.
However, such a flow would be more energetic and so could reach higher elevations and further north, away from the valley and into currently populated areas. MVO might be able to detect some precursory signs of lateral blast or “normal” collapse events, but could not guarantee to give an early warning.
Source: mvo.ms
Although this is not yet as large as the dome was prior to the 12 July 2003 collapse, the rate of growth towards that size is about three times faster than in 2003. Over the next year we regard a major collapse of the dome down the Tar River Valley to be the most likely outcome, such a collapse would be accompanied by a major ashfall.
However, we regard a pyroclastic flow/surge reaching the lower Belham Valley to be more likely than six months ago. There are two main ways in which this could occur: from a “normal” collapse of a part of the dome down Tyre’s Ghaut and into the Belham Valley, and from a lateral blast (a sideways explosion) to the north or west, as happened to the southwest on Boxing Day 1997.
The volume of the dome that could collapse down the Belham Valley could be as great as 20 million cubic metres or even more in future if the dome continues to grow. The possibility of a lateral blast has increased because of several factors: the rate of growth of the dome, the preferential growth on the northwestern side of dome and the likely pressurization of the dome interior. Such a blast could be triggered by exposing the hot, pressurized interior of the dome, either from a large “normal” collapse or from failure of the crater wall. The likelihood of such a lateral blast-derived pyroclastic flow in the lower Belham Valley is less than the equivalent “normal” collapse-derived flow.
However, such a flow would be more energetic and so could reach higher elevations and further north, away from the valley and into currently populated areas. MVO might be able to detect some precursory signs of lateral blast or “normal” collapse events, but could not guarantee to give an early warning.
Source: mvo.ms