St Vincent And The Grenadines Remains On Orange Alert, As Effusive Eruptions Occur At La Soufriere Volcano.
(By Ernesto Cooke) – Lead Scientist monitoring the La Soufriere volcano Dr Thomas Christopher says the team is working to survey the dome at least once per week.
Thomas says the team should be on the summit today to get a more unambiguous indication of how fast the new dome is growing.
The last visit revealed that the dome is just under some 6 million cubic meters.
The Disappearance Of Groundwater In The Crater
Thomas speaking on the disappearance or drying out of groundwater within the crater says they should have been seeing SO₂ (Sulphur Dioxide) since December 2020.
“ As long as you have a volcano erupting, which La Soufriere has been doing, you would expect to see Sulphur Dioxide coming out in the emissions”.
“Sulfur dioxide or sulphur dioxide is the chemical compound with the formula SO ₂. It is a toxic gas responsible for the smell of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of fossil fuels contaminated with sulfur compounds.”
The lead Scientist says this was not the case when they began measuring gases in January.
“ As I said, we suspected that the Sulphur Dioxide was interacting with the water creating mild sulfuric acid underground, we did not see it, the water was hiding from us, now we have started to see it from February 1st ”.
Thomas says there is now less water to interact with the Sulphur Dioxide.
“ We are still not seeing all of it, because when we look at the gas chemistry, we see that there are hydrothermal gases within the dome, so we see more of it than in the past, and yes the water is drying out, but not totally”.
Hydrothermal gases are related to volcano-hosted hydrothermal systems and characterised by compositions that result from the interaction of magmatic gases with a liquid phase.
Why Is The Water Disappearing
Dr Thomas Christopher says the disappearing water is due to the effusive eruptions taking place at La Soufriere.
“ The average person needs to understand how hot this magma is and how much of it is there, you have a large volume of it, so its heating up the ground, the steam you are seeing, is some of that water boiling off”.
The Continued Eruptions
Dr Christopher says SO₂ is the most accessible gas for the team to get a mass flux.
Mass Flux: The rate at which a given amount of gas leaves a vent.
The lead Scientist says if a mass flux of SO₂ is available daily, the team can have a good idea of how fast magma is coming out at the top.
“ If you fill a cup to the limit, it holds a fixed volume of water; it is the same for the magma there is a fixed volume of gas in a fixed volume of magma. So if you see more gas, it means more magma is present”.
Further Reading
The new dome continues to grow with a lateral spreading of material towards the north and south, with a preferred northward growth observed.
Damage to vegetation, from acidic gases emitted from the growing dome, downslope of the summit continues.
The National Emergency Management Organisation is reminding the public that there is no evacuation order or notice.
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.
NEMO will continue to provide regular updates on all activities taking place at La Soufriere.
The Last Eruption Of The la Soufriere Volcano Occured In 1979.
