MVO reported to the Washington VAAC that increased activity began at Soufrière Hills on 10 February. That day, satellite imagery showed a prominent hotspot at the volcano and a NW-drifting ash plume at a height of ~3 km (10,000 ft) a.s.l. Ash-and-gas emissions continued through 15 February, producing plumes to a height of ~2.7 km (9,000 ft) a.s.l. MVO reported that on 15 February, there was markedly less volcanic activity, with steam and a small amount of ash emitted to ~1.4 km (4,450 ft) 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.

Source: Washington Volcanic Ash Advisory Center (VAAC)