Report on Soufriere St. Vincent (Saint Vincent and the Grenadines) — 5 May-11 May 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
5 May-11 May 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Soufriere St. Vincent (Saint Vincent and the Grenadines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 May-11 May 2021. Smithsonian Institution and US Geological Survey.
Soufriere St. Vincent
Saint Vincent and the Grenadines
13.33°N, 61.18°W; summit elev. 1220 m
All times are local (unless otherwise noted)
On 6 May government authorities lowered the Alert Level to Orange for Soufrière St. Vincent (often simply referred to as “La Soufriere”) based on recommendations from University of the West Indies Seismic Research Centre (UWI-SRC). The public was allowed to return to their homes in the Yellow and Orange zones, though access to the Red Zone remained restricted. UWI-SRC noted that over the previous few days continuing lahars had mobilized boulders 5 m in diameter and were steamy in areas where they contacted hot deposits. A small lahar signal was recorded at 0740 on 7 May. Sulfur dioxide emissions were measured from a boat near the W coast, yielding a flux of 208 tons per day on 9 May. Seismicity remained low through 11 May with only a few long-period earthquakes recorded by the seismic network.
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