Sulfur dioxide emissions detected at Soufriere volcano, St. Vincent and the Grenadines

Sulfur dioxide emissions detected at Soufriere volcano, St. Vincent and the Grenadines

Multi-Gas measurements conducted at La Soufriere volcano on February 1, 2021, confirmed the presence of sulfur dioxide (SO2) for the first time. Filter packs used to measure hydrogen chloride (HCl), Hydrogen fluoride (HF), Sulfur dioxide (SO2) and Hydrogen Sulfide (H2S) will need to be sent abroad for analyses.

The fact that SO2 is now coming out of the volcano suggests that the ground water is drying up, National Emergency Management Organization (NEMO) reports.

The absence of Sulfur dioxide in the early stages of the eruption was due to the interaction of sulfur dioxide with the ground water (Sulfur dioxide was dissolving in the ground water).

The lava dome survey on February 1 produced the following reasults:

estimated length 511 m (1 676 feet), width 231 m (757 feet), height 93 m (305 feet), total volume 5.93 million m3 (209.4 million ft3).

Image credit: UWI-SRC

Observations made of the crater floor suggest that another fire occurred in the north western region of the crater (to the immediate north of the dome) which affected vegetation on vertical face of the crater.

The National Emergency Management Organisation is reminding the public that no evacuation order or notice has been issued.

NEMO continues to appeal to the public to desist from visiting the La Soufrière Volcano, especially going into the crater, since doing so is extremely dangerous.

Image credit: NEMO

Image credit: NEMO

Geological summary

Soufrière St. Vincent is the northernmost and youngest volcano on St. Vincent Island. The NE rim of the 1.6 km (1 mile) 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 (1.3 miles) wide Somma crater, which is breached widely to the SW as a result of slope failure.

Frequent explosive eruptions since about 4 300 years ago produced pyroclastic deposits of the Yellow Tephra Formation, which blanket 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 in a lake that filled the crater prior to an eruption in 1979.

The lake was then largely ejected during a series of explosive eruptions, and the dome was replaced with another.

Featured image credit: UWI-SRC


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