Report on Soufriere Hills (United Kingdom) — 31 January-6 February 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
31 January-6 February 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 January-6 February 2001. 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 activity at the Soufrière Hills Volcano was lower than during the previous week, although the lava dome continued to grow. The level of seismicity was also generally lower. During the morning of 29 January a very low-energy swarm of 20 volcano-tectonic earthquakes occurred to the NE of the volcano. During the week, brief observations revealed that volcanic activity remained concentrated on the SE side of the dome. On 1 February, a small pyroclastic flow was observed in the White River Valley. It traveled ~1 km to the SE and produced a small ash cloud that rose to a maximum height of ~1.5 km a.s.l.
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.