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Report on Soufriere Hills (United Kingdom) — 12 October-18 October 2005

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 October-18 October 2005
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2005. Report on Soufriere Hills (United Kingdom). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 October-18 October 2005. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (12 October-18 October 2005)


Soufriere Hills

United Kingdom

16.72°N, 62.18°W; summit elev. 915 m

All times are local (unless otherwise noted)


Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 7-14 October. Lava-dome growth mostly occurred on the W side of the dome, which was largely obscured by clouds and steam. Observations suggested that the lava-dome growth rate increased, with preliminary calculations suggesting a rate of at least 2 cubic meters per second. Incandescence was visible at the lava dome on a video camera at night. The sulfur-dioxide flux averaged 580 metric tons per day (t/d), above the long-term eruption average of 500 t/d. The hydrogen-chloride versus sulfur-dioxide ratio increased to about 1.

Geologic Background. 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.

Source: Montserrat Volcano Observatory (MVO)