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Report on Soufriere Hills (United Kingdom) — 31 October-6 November 2001

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 October-6 November 2001
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2001. Report on Soufriere Hills (United Kingdom). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 31 October-6 November 2001. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (31 October-6 November 2001)


Soufriere Hills

United Kingdom

16.72°N, 62.18°W; summit elev. 915 m

All times are local (unless otherwise noted)


Beginning on 26 October, seismicity at Soufrière Hills was at low levels until it increased on 1 November. Clear weather conditions allowed observations of the lava dome on 31 October and 1 November. The active lava dome had grown substantially and appeared to switch growth direction from the NE to the E, where a massive, near-vertical headwall had developed. Several small pyroclastic flows were generated by material avalanching off the eastern flank of the dome. Cycles of mostly hybrid earthquakes, with a coincident increase in rockfalls, were weak until they strengthened on 1 November. Mudflows occurred in the Belham Valley during several days with periods of torrential rainfall.

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)