Report on Soufriere Hills (United Kingdom) — 7 February-13 February 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
7 February-13 February 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Soufriere Hills (United Kingdom). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 7 February-13 February 2007. Smithsonian Institution and US Geological Survey.
16.72°N, 62.18°W; summit elev. 915 m
All times are local (unless otherwise noted)
During 7-13 February, growth of the Soufrière Hills lava dome continued on the W side. A small lobe was observed on 7 February growing to the SW. On 8 February, three pyroclastic flows traveled a maximum distance of a few kilometers E down the Tar River Valley. At least one of the pyroclastic flows was the result of a small collapse from the S or SW part of the dome. Small pyroclastic flows traveled NW down Tyres Ghaut on 9 February and down the northern flanks onto Farrell's Plain on 12 and 13 February. Based on satellite imagery, information from MVO, and pilot reports, the Washington VAAC reported that ash-and-gas and steam plumes drifted predominantly NW during 10-13 February. Plumes reached a maximum altitude of 2.7 km (9,000 ft) a.s.l. on 13 February
Based on a news article on 13 February, the lava-dome volume was approximately 250 million cubic meters, surpassing the previous record size of 240 million cubic meters in 2003.
Geological Summary. The complex, dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. The volcano is flanked by Pleistocene complexes to the north and south. English's Crater, a 1-km-wide crater breached widely to the east by edifice collapse, was formed about 2000 years ago as a result of the youngest of several collapse events producing submarine debris-avalanche deposits. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits, including those from an eruption that likely preceded the 1632 CE settlement of the island, allowing cultivation on recently devegetated land to near the summit. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but no historical eruptions were recorded until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.