La Soufrière Dome Could Overtop Crater In Coming Months

If the ongoing effusive eruption of the La Soufrière Volcano continues at its current rate, scientists at the University of the West Indies Seismic Research Center (UWI SRC) are monitoring the potential for the new dome to overtop the existing crater rim. However, monitoring scientists emphasize that there will be ample warning if this were to occur.

According to Professor and Geologist at the UWI SRC, Richard Robertson, if the rate of magma effusion continues as it has over the last several weeks, the dome will become “bigger and bigger,” potentially filling the space in the existing crater.

He notes that as the new dome gets close to the existing crater rim, it is possible that the hot rock becomes incandescent at night, allowing those from far away to see a glow from La Soufrière. Robertson reiterates that this is what you would see if the effusive phase of the eruption maintains over a sustained period of time.

However, what is of concern is that there is a portion of the crater rim that is called a “low lip” where some of the newly formed rock can overtop, cascading down the flanks of the volcano. Robertson explained, “As it does that, the gases in it [the rock] comes out and produces these little throws that are hot and can go a bit further down the flank.”

Where this “lower lip” exists, fortunately, it is uninhabited and there are no areas further downslope where villages would be compromised. What this activity may bring in the coming months if this scenario occurs would be more attention to the volcano. “It is a possibility and it could generate more ash, and more steam. People are going to see it being visibly more active, even in the effusive stage.”

The Director of the UWI SRC, Dr. Erouscilla Joseph, explained that scientists are using very crude estimates from the few aerial reconnaissance flights to calculate the volume of rock produced, and thus the rate of effusion.

As of January 4th, 2021, Dr. Joseph placed the SRC’s estimates at 700,000m3 of erupted magma. Joseph stressed the estimate’s uncertainty, but if the current effusion rate continues, it will take approximately six and a half months to cross the crater rim. However, the La Soufriere volcano is a dynamic system and changes daily.

As of January 12th, 2021, Professor Robertson gave an updated estimate – the new dome was growing at an approximate rate of 1.5m3 per second, with 1,600,000m3 of erupted magma, more than double the January 4th estimate.

Reiterating his position that there will be ample notice before overtopping occurs, Robertson explained with continuing observation flights and already set up monitoring cameras, with additional cameras to be installed, “we will know before it’s gotten to that stage, where it will start glowing or it is going to spill over.”

“Even with effusive eruptions and this eruption, we’ll be looking to make sure we’re in a position to tell people before it happens, before people see it, that it is about to happen.”

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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