Report on Soufriere Hills (United Kingdom) — 6 December-12 December 2000
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 December-12 December 2000
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2000. Report on Soufriere Hills (United Kingdom). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 6 December-12 December 2000. Smithsonian Institution and US Geological Survey.
16.72°N, 62.18°W; summit elev. 915 m
All times are local (unless otherwise noted)
The MVO reported that during 1-8 December volcanism continued at an elevated level, with continued growth of the lava dome. Seismic activity was comparable to the previous week. The main focus of activity remained on the volcano's eastern flanks, although some small rockfalls were observed on the western side of the new growth. Rockfalls and small pyroclastic flows regularly traveled to the NE down the upper reaches of Tuitt's Ghaut. The dome was observed intensely glowing. Spines continuously grew and collapsed on the summit of the dome, with the highest spine reaching 1,060 m a.s.l. Strong hot spots, and low-level ash clouds (<2 km a.s.l.) associated with the numerous rockfalls and pyroclastic flows were visible on GOES-8 imagery.
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.