Can A La Soufrière Eruption Trigger A Tsunami?

Plume of steam and volcanic gases emanate from the new La Soufrière volcanic dome. (UWI SRC/Richard Robertson)

Present La Soufrière Alert Level:ORANGEThere is a highly elevated level of seismic and/or fumarolic activity or other unusual activity. An eruption may begin with less than twenty-four hours' notice.

With the ongoing effusive eruption at the La Soufrière Volcano in St. Vincent, a common question has been if the eruption becomes explosive, is there a risk of a tsunami?

Tsunamis are no stranger to the Eastern Caribbean – whether the event was triggered within the Caribbean region, for far across the Atlantic. Volcanically-triggered tsunamis are also not unheard of in our area as well. However, according to Professor and Geologist at the UWI SRC, Richard Robertson, the threat of a tsunami, at this time, is very unlikely.

Volcanic tsunamigenesis is generally due to a large mass entering a body of water (a lake, sea, or ocean) and displacing a significant volume of water. In volcanic eruptions, large parts of a volcano can fail – either because of the explosive eruption or a large volume of loose material falling into the water.

Professor Robertson explained that this scenario concerning La Soufrière is “very unlikely.” He went on to give some regional context, “Of course, all of the volcanoes in the region has had some kind of that activity – what is called flank collapse. It is possible in the realm of any volcano.”

Scheme of tsunami generation by a volcanic eruption and flank collapse (UNESCO).
Scheme of tsunami generation by a volcanic eruption and flank collapse (UNESCO).

However, he reiterated, “Right now, we don’t think, the fact that we have a small dome, and it is not beginning to get to the stage where it is pushing too hard on the crater wall, we don’t think a flank collapse is likely. Therefore, the possibility of a tsunami is not very high.”

Driving the point home, Robertson concluded, “It is one of the many things we look at as future possibilities. It can happen, but we don’t think it is something that will happen now.”

Volcanic Hazard Map for the La Soufrière Volcano, St. Vincent (UWI SRC/NEMO)
Volcanic Hazard Map for the La Soufrière Volcano, St. Vincent (UWI SRC/NEMO)

The National Emergency Management Organisation reminds 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 until the scientists advise that it is safe.

Official information will originate from St. Vincent and the Grenadines National Emergency Management Organization and the University of the West Indies Seismic Research Center.

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