University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrière St. Vincent’s main crater continued to slowly grow during 17-23 March, expanding to the N and S. A team visited the dome on 19 and 23 March to make observations, take measurements, and maintain monitoring equipment. Gas-and-steam continued to rise from the top of the dome as well as along the contact between the old and new domes. As of 19 March the dome was 105 m tall, 921 m long, 243 m wide, and had an estimated volume of 13.13 million cubic meters. The Alert Level remained at Orange (the second highest level on a four-color scale).

Geological Summary. Soufrière St. Vincent is the northernmost and youngest volcano on St. Vincent Island. The NE rim of the 1.6-km wide summit crater is cut by a crater formed in 1812. The crater itself lies on the SW margin of a larger 2.2-km-wide caldera, which is breached widely to the SW as a result of slope failure. Frequent explosive eruptions after about 4,300 years ago produced pyroclastic deposits of the Yellow Tephra Formation, which cover much of the island. The first historical eruption took place in 1718; it and the 1812 eruption produced major explosions. Much of the northern end of the island was devastated by a major eruption in 1902 that coincided with the catastrophic Mont Pelée eruption on Martinique. A lava dome was emplaced in the summit crater in 1971 during a strictly effusive eruption, forming an island within a lake that filled the crater. A series of explosive eruptions in 1979 destroyed the 1971 dome and ejected the lake; a new dome was then built.

Sources: University of the West Indies Seismic Research Centre (UWI-SRC), National Emergency Management Organisation (NEMO), Government of Saint Vincent and the Grenadines