For Vincentians asking questions about the possibility that the La Soufriere Volcano could have an explosive eruption, Volcanologist Professor Richard Robertson on the latest events at the volcano says ‘your warning you are getting now is your warning.’
New magma is trying to push through and this is not necessarily a good thing.
Robertson speaking on the RoundTable Talk programme last night walked through the changes that have been observed at the new dome.
He says as of March 23 proper earthquakes are now being felt. Most of the seismicity was related to the dome building itself. Now there are volcanic tectonic earthquakes with rock breaking and magma trying to get through the ground. This tends to have a lot more energy and because they are bigger, there is the possibility it is being felt, says Robertson.
Those living close to or on the volcano have reported feeling tremors.
The professor explains that as magma tries to push its way through the ground there is rock above it and the magma coming through builds up enough and it pushes through the rock, breaks it and generates a seismic signal.
“The earthquakes are telling us magma is trying to get to the surface. It is something we are keeping a close eye on, whether it is indicative of something changing if it going to move from effusive to something different. That is something we are monitoring closely as the hours and days go by,” says Robertson.
It is also possible that the magma which was building the dome could be old. The professor says late last year something caused magma to surface and it is possible the magma below the surface was there since the 1979 eruption. He says the magma came from what they think is a shallow source.
Roberston says what is being seen now is indicative of the fact that more material, other magma, is also trying to come out and because it is deeper below the surface there is a lot more resistance for it to come out. For it to come out it has to build up enough pressure and push through.
So what does this mean? Professor Robertson says there is the possibility that it will get to the surface and because it is fresher it could change the way in which the material is erupting whereby it could change from effusive to being something that is a bit more energetic.
He says: “Remember we were always talking about the fact this volcano it could keep on doing effusive things, it could stop or it could go explosive. One of the things which would drive it to become explosive is fresh material coming in, new material to give it energy.
This is the first indication that maybe this is happening. We have to track it now to see if it is indicative of that. This magma is deeper down trying to find a pathway through and is causing vibrations.
It is probably not a good thing that is happening because this eruption could go to a stage, we all don’t really want to get to, but it also tells us the instrumentation is working and detecting events that could indicate something else that could happen.”
Robertson says the volcano is giving citizens plenty warning however there is no need to panic and the public should have plans in place just in case movement is required to the South of the island.
The professor who took questions during the television programme also responded to concerns related to the southern crater wall which the dome has been pressing against. He says there is a possibility it can compromise the southern crater wall.
Robertson explains this is due to the obstruction of the 1979 dome. There are a set of reflectors on the southwestern wall to look for the potential failure of that wall, to observe whether the weight of the new dome resting on the crater wall could cause it to fail and if there is potential for hot material getting out the crater.
He says it is something they are concerned about as a potential explosion could result in the collapse in that direction.
Robertson says such a scenario could potentially cause a lot of damage and destroy a lot of property in that area.
Meanwhile, Director of NEMO Michelle Forbes says the organisation is on heightened alert and has started contacting sub-committees and key agencies informing them that they ‘need to be stepping up things’ and be on the alert in case things start to escalate.
Forbes notes over the past months NEMO has been saying the public should be ready for change and citizens should heighten their preparedness in case the event continues to escalate.