La Soufrière Update #28: Groundwater Drying Up, Increased Sulfur Dioxide

The summit of the La Soufrière Volcano on 24th January 2021 showing the growing dome and burnt vegetation. (Rommel De Freitas)

Present La Soufrière Alert Level:YELLOWThe La Soufrière Volcano is restless. Seismicity and/or fumarolic activity are above the historical level at the volcano, or other unusual activity has been observed. This unusual activity will be specified at the time that the alert level is raised. This is level two of four.

The National Emergency Management Organization, in their latest bulletin, advised that some gas measurements were done on Monday using a Multi-Gas Instrument and a filter pack. The Multi-Gas measurements were successful and showed the presence of sulfur dioxide gas coming out of the volcano. The filter packs used to measure gas species such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and hydrogen sulfide will need to be sent abroad for analyses.

Dr Thomas Christopher, Lead, Scientific Team, sets up, deploys and retrieves volcanic gas samples from #lasoufrière’s…

Posted by UWI Seismic Research Centre on Thursday, February 4, 2021

Concerningly, on Monday 1st February 2021 it was the first day that Sulfur dioxide gas was detected in the eruption. Scientists suspect that the absence of sulfur dioxide in the early stages of the eruption was due to the interaction of sulfur dioxide with the groundwater. The sulfur dioxide was dissolving in the groundwater at that time. However, the fact that sulfur dioxide gas is now coming out of the volcano suggests that the groundwater is drying up.

The latest dimensions of the  La Soufrière Volcano lava dome according to the UWI SRC
The latest dimensions of the  La Soufrière Volcano lava dome according to the UWI SRC

The dome is now estimated to have a volume of 5.93 million cubic meters as of February 3rd, 2021. Observations made of the crater floor suggest that another fire occurred in the northwestern region of the crater (to the immediate north of the dome) which affected vegetation on the vertical face of the crater.

Electronic Distance Measurement (EDM) target was hit from the Chateaubelair area using a total station on Monday while the team was on the summit.

According to NEMO, this is good news for the establishment of the EDM network on the western flank of the volcano. The EDM Network is used to assist with measurements of deformation associated with the flanks of the volcano.

There is NO ‘explosive’ eruption at the La Soufrière volcano at this time. La Soufrière continues to have effusive eruptions, as hot magma reaches the surface at extreme temperatures. This appears in the night as fire or a bright red glow above the crater. As the dome gets higher and closer to the crater’s rim, this phenomenon will continue to be visible on clear nights.

The alert level remains at Orange. The volcano continues to exude magma on the surface and steam can still be observed from the Belmont Observatory. Persons living in areas close to the volcano should expect strong sulfur smells for several days to weeks, depending on changes in wind direction.

The NEMO 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 and especially going into the crater since doing so is extremely dangerous.

The @uwiseismic and NEMO continue to advise access to the #LaSoufriere Volcano is strictly prohibited at this time….

Posted by Trinidad and Tobago Weather Center on Thursday, January 14, 2021

According to the SRC, the new volcanic dome is extremely dangerous for those in close proximity as it can explode at any time without warning. People have been killed in this way. This warning comes as images from a birthday photoshoot surfaced on social media.

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)

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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