Activity including rapid lava-dome growth, pyroclastic flows, and ash venting increased at Soufrière Hills during 3-9 January. Dome growth was concentrated in the NW quadrant which was the highest part of the dome. Pyroclastic flows, originating from the NW, were observed in Tyres Ghaut (NW), Gages Valley (W), and N, behind Gages Mountain and accompanied by ash venting. On 4 January, a notable event resulted in simultaneous pyroclastic flows in Tyres Ghaut and Gages Valley, and a resultant ash cloud reached an altitude of 2.5 km (8,200 ft) a.s.l. The maximum distance for the Gages Valley flow was 4 km. During 6-7 January, distances of pyroclastic flows increased in Tyres Ghaut and possibly exceeded 1.5 km.

Activity including rapid lava-dome growth, pyroclastic flows, and ash venting increased at Soufrière Hills during 3-9 January. Dome growth was concentrated in the NW quadrant which was the highest part of the dome. Pyroclastic flows, originating from the NW, were observed in Tyres Ghaut (NW), Gages Valley (W), and N, behind Gages Mountain and accompanied by ash venting. On 4 January, a notable event resulted in simultaneous pyroclastic flows in Tyres Ghaut and Gages Valley, and a resultant ash cloud reached an altitude of 2.5 km (8,200 ft) a.s.l. The maximum distance for the Gages Valley flow was 4 km. During 6-7 January, distances of pyroclastic flows increased in Tyres Ghaut and possibly exceeded 1.5 km.

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.

Sources: Washington Volcanic Ash Advisory Center (VAAC), Montserrat Volcano Observatory (MVO)