Geologist issues warning to residents in the red zone to let common sense prevail
Richard Robertson
November 11, 2022
Geologist issues warning to residents in the red zone to let common sense prevail

Geologist, Professor Richard Robertson has issued a warning to residents in the volcanic red zone who may be tempted to cross swollen rivers to let common sense prevail.

Speaking on NBC’s Face to Face programme on Monday, November 7 Robertson made it clear that such a risk is not worth losing one’s vehicle, or their life.

He said that when people take the risk to cross these areas, they often believe that others will help them if there is any difficulty.

He, however cautioned, “that might not always be the case.”
Persons are therefore putting themselves at unnecessary risk by crossing rivers which are in a state of flood.

The Vincentian Geologist who is attached to the Seismic Research Centre at The University of the West Indies (The UWI) St Augustine Campus, suggested that people should simply wait for the flow of the water to subside before attempting to cross.

“Eventually, the water will run off and you would be able to cross.”

So far during this wet season, persons have had to contend with flooded rivers at Noel and Overland which have left them stranded for long periods.

The government is currently installing Bailey Bridges at these two crossings to ease the problems faced by commuters.
Professor Robertson added that because of the eruptions last year, it does not take much rainfall for the rivers to flood.

He said all that is needed, is about 20 ml of rainfall over a day or less in the mountains to result in floods or lahars.

Following the volcanic eruptions last year, Professor Robertson had warned Vincentians that they will have to contend with the problem of lahars for years to come.

On Monday, he again gave this reminder and estimated that it could continue for “the next year or two, or probably longer.”

The Geologist pointed out that there is no vegetation on the upper 1/3 slope of the Soufriere volcano and this situation, combined with a lot of loose material and rainfall would result in flash floods or lahars.

Consequently, the river crossings will be inundated and difficult to cross.

Professor Robertson also said that as a result of the 32 explosive eruptions in April last year, millions of tonnes of material were ejected from the volcano and these “are now resting at the top of the mountain.”

The eruptions also robbed the upper slopes of the Soufriere Mountain of its vegetation and given this situation, “it means that there is going to be increased rainfall run off”.

Robertson said it is now “easy for the rain to take away” the material that was produced by the eruptions.

“Whenever rain falls, its gonna bring all that material down, it will come down in the valley where the river is.”

He added that once this material gets lower down the valley, there will be problems at the river crossings.

As long as there is little or no vegetation up hill, Professor Robertson said “ the potential is always going to be there, that when rain falls, it is going to come down.”

Explaining that lahars can be generated with as little as 20 ml (a bucket and half) of rainfall, the Professor warned that this can happen even when the sun is shining in other areas, but there was rainfall in the mountain or any catchment area.

He said that in some areas, there is up to 100 meters of ash, and the soil is buried under the ash and once situation remains, problems with lahars will continue to be experienced.

For persons living North of the Rabacca Dry River, Professor Robertson suggested that they put a contingency plan in place for when the rivers are in flood and crossing is too risky.

Apart from the floods and the lahars, the Geologist assured the population that there is “nothing to worry about.”

“Nothing unusual is happening with the volcano,” and that “all is well.”