By: Staff Writer
April 27, 2021
St Vincent and the Grenadines is not out of the volcanic danger zone yet as Prime Minister Gonsalves warns to not drop your guard and resist the temptation of laziness.
The distance between the tremors at the La Soufriere volcano remains the same but experts are seeing more earthquakes, as the volcano continues to have explosive eruptions since it first started in the beginning of April.
Dr Richard Robertson, professor of geology and past director of the University of the West Indies Seismic Research Centre (UWISRC), speaking on a webcast last week said that a pattern seismic activity attributed to the La Soufriere volcano continues to happen after the April 18 explosive eruption.
He added: “We continue to have small, long period and hybrid earthquakes… the numbers and the rate of the long period and hybrid earthquakes have increased.”
Volcanic hybrid earthquakes comprise a class of pre‐eruptive low‐frequency seismic signals, having high‐frequency onsets followed by low‐frequency ringing. The unusually low frequency of these earthquakes can result from low rupture velocities combined with strong path effects due to their shallow source.
On the other hand, deep long-period earthquakes (DLPs) are an enigmatic type of volcanic seismicity that sometimes precedes eruptions but mostly occurs at quiescent, or dormant, volcanoes. These earthquakes are depleted in high-frequency content and typically occur near the base of the crust.
Dr Robertson also said: “So the pattern of the periods when you might have explosions, and that you have intervening long periods of hybrids, and long period events continuous.”
Dr Robertson warned however that it is “unclear” what all of this activity means for future eruptions at La Soufriere, and said it could mean that there is a “battle” between the forces that want to push the material out and the forces resisting it, and that this could possibly be the reason for the hybrid earthquakes.
“It might be indicative of the fact that a dome or something is resisting the movement of material upwards. It’s started to indicate that stuff below is trying to come out,” said Dr Robertson and also that it could be gas or magma trying to come out and further warned that these next few days will be critical as to whether La Soufriere has continued explosion or just “dome growth.”
The explosive eruptions will stop at some point said Dr Robertson and it probably end within a few weeks or months, however the question is when will it stop. He does not feel that it will continue on indefinitely like the Montserrat volcano eruption of, 1995 which lasted for 60 weeks on the initial eruption and rendered the Southern part of the island uninhabitable with other eruptions happening in 1997 and all the way to 1999.
Dr Ralph Gonsalves, prime minister of SVG, encouraged listeners and relief workers to continue not to drop their guard, and resist the temptation of getting lazy on monitoring the volcanic activity, “we have to keep planning and keep away from the red zone.”
Dr Gonsalves also said: “I had a conversation with the Commissioner of Police and though we have security personnel at the entry to the red zone. The security has not been at the tightest in allowing access to the red zone.
“Tt was decided that he would move the police officers at Mount Young Bridge and put them at Rabacca (Bridge). Because as Georgetown is in the red zone, you still have a number of people in Georgetown, because it’s at the lower end of the red zone. But where the real danger would be would be people who go over in Rabacca.”