MVO reported no evidence of lava-dome growth at Soufrière Hills during 18-26 July. At least six eruptive events occurred during 20-22 July, each producing ash plumes that rose to altitudes of 2 km (6,000 ft) a.s.l. or lower. The ash plumes drifted W; ashfall was reported in Old Towne. Rumbling noises were heard in nearby areas and lightning strikes were observed. Small pyroclastic flows during 20-21 July traveled E down the Tar River valley with the largest one reaching within 500 m of the ocean. The Alert Level remained elevated at 4 (on a scale of 0-5).
On 26 July, seismicity increased significantly and then decreased. Seismicity increased again at approximately 0100 on 27 July and continued at a high level until about 0935 when a short series of eruptive events started. The first and largest ash-venting event of this series produced an ash plume that rose to an altitude of 2.5 km (8,000 ft) a.s.l. and drifted W and NW. Ashfall was reported in Plymouth and St George’s Hill. Two events that followed produced ash plumes to an altitude of 1.5 km (5,000 ft) a.s.l.
A partial lava-dome collapse began at 1127 on 28 July without any precursory activity. Part of the dome’s W flank collapsed and generated pyroclastic flows that reached Plymouth and the sea. A few explosions during the collapse produced ash plumes; the largest ash plume rose to an altitude of 12 km (40,000 ft) a.s.l.
Source: Montserrat Volcano Observatory (MVO) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”