Several mud flows recorded at La Soufriere volcano

A lahar is a rapidly flowing dense mixture of rock debris, ash and water. They have the consistency of wet concrete as they flow and can happen during and after eruptions.

The Seismic Research Centre (SRC) of the University of the West Indies (UWI) said that signals from several lahars were recorded on Tuesday during and after a period of rainfall.

“Following the rainfall, large amounts of steam could be seen billowing up from a valley south of the summit. This would have been generated when the runoff encountered buried volcanic deposits that were still hot.

“The volcano continues to erupt. Explosions with accompanying ashfall, of similar or larger magnitude, can restart with little or no warning. The volcano is at alert level Red,” the SRC added.

The National Emergency Management Organisation (NEMO) says as a result of the mud flows, “the Royal St. Vincent and the Grenadines Police Force will be restricting person travelling into the Red and Orange Hazard Zones.”

NEMO further noted that the St. Vincent and the Grenadines Meteorological Services had said that occasional showers were expected to continue during the course of the day and from late Wednesday into the end of the week.

“Residents and motorists should remain alert due to rain-soaked ash and possible poor visibility due to volcanic ash,” NEMO said, urging people “to desist from visiting the Red and Orange Volcano Hazard Zones due to the potential danger.”

Meanwhile, the experts monitoring the volcano, which erupted explosively on April 9 and has had a series of explosions since, say they would suggest cleaning up, but not occupancy of the Orange Zone.

Volcanologist and lead scientist, Professor Richard Robertson, said that the monitoring network is not as optimal as they would like as some stations were destroyed in the eruption.

Unlike before April 8, when the team gave a clear indication that the volcano was heading to an explosive eruption, “there is no guarantee that that can happen again,” Robertson said.

“So I think it is best to be cautious, at least in the next few weeks or so and let’s see if it keeps quiet. If it keeps quiet, that question would be easier to answer as we go along,” he said, in response to a question posed by Prime Minister Dr. Ralph Gonsalves as to how much warning the nation might get ahead of another explosion at the volcano.

Seismologist Roderick Stewart said that there would be “enough” time, saying “it could be as little as hours, it could even be reaction to something that’s happening at the summit. You might actually see activity… It’s on short notice that people might have to move out,” Stewart said.

Robertson told Gonsalves on their daily programme on the state-owned NBC Radio that he would always be cautious about people going back into the Red Zone.

“The volcano is telling us that it has entered this period where there is no clear indication that it’s … heading to an explosion though things could change quite rapidly,” Robertson said of La Soufriere, which has been quiet since its last explosion on Friday.

“That is why we have to be cautious,” he said, noting that there are certain areas in the Orange Zone that may not have been affected by heavy ash fall.

“So, yes, clean up in those areas is a good idea now, when it is not exploding. In terms of the Red areas, I would certainly not suggest any movement north of the Rabacca Dry River,” Robertson said, adding that clean up could take place in the southern parts of Georgetown when the volcano is not exploding.

“But people, if they do that, they have to bear in mind that you may have to react quickly if events pick back up and go back to explosive,” he said, even as he noted that the Rabacca area is prone to lahars.

Robertson suggested that on the leeward side of St. Vincent, clean up could take place south of Chateaubelair.

“People have been cleaning up their roofs in Chateaubelair. I know that. But when you get to those areas you are getting into areas that are a bit more on the marginal side. Even with the activity levels now,” he said.

He said that once the volcano is not exploding, people could occupy, safely, places like Belmont (leeward) and Troumaca.

“The key things are the explosion and heavy ash. Because these areas were never going to be compromised by pyroclastic flows,” Robertson said, but suggested clean up rather than occupation of places north of Petit Bordel.

There is always the potential that the volcano could “start back up” and once it starts but up they have to move out again, Robertson said.

He, however, said that with the volcano in its current stage, it is just really the conditions of the ash that is really most hazardous.

“The thing with volcanic hazards is to minimise your exposure by decreasing the amount of time you are exposed to the thing that might put you in harm’s way. So that is why, as scientists, we do work sometimes in areas on the volcano but we minimise impact and we have certain protocols we operate under. If you have that, it is possible to do things.”

He said that the monitoring team needs to ensure that people do not drop their guard and the scientists have to make sure that the volcano is heading in a particular direction before they allow people back into the danger zone.

“There is some work that can be done in the interim but people need to be prepared because it can pick back up again and it can pick back up quickly and we will have to respond to that.”.

Meanwhile, the United Kingdom has announced a further 550,000 pounds sterling, (US$695,000) to the volcano relief efforts in St. Vincent and the Grenadines.

This takes London’s contribution to over 800,000 pounds sterling (US$1 million) since the eruption began on April 9 and will be delivered via the World Food Programme (WFP).

The additional money comes amidst criticism of the United Kingdom after it initially gave 200,000 pounds sterling (US$278,000) to the Caribbean Disaster Emergency Management Agency (CDEMA), which enabled the immediate mobilisation of regional support teams and urgent supplies for the initial relief effort.

With the latest amount, the UK will help provide food, water and other essentials, following the volcanic eruption.

Funding will help families meet their essential needs for three months and the contribution will go to World Food Programme, in response to UN appeal, a press release said.  (CMC)