La Soufrière may be quieting down – experts

UWI volcano watchers said Wednesday that seismic activity at the La Soufriere volcano in St Vincent seems to be slowing down, but warned that it is still too early to say whether it has returned to sleep after its third eruption in nearly 119 years.

“Right now the volcano seems to be getting rid of all the gas that was built up inside it, and it may actually be in the process of reforming a dome after having destroyed the old one,” said Professor Richard Robertson, head of the UWI Seismic Research Centre’s Belmont observatory in St. Vincent. “It may go back dormant, but there is the possibility that it may erupt again in a few weeks or months.”

Fellow volcanologist Roderick Stewart, who watches Montserrat’s Soufriere Hills volcano, said: “We are quick to say it is starting, based on the increased intensity of the tremors, but we need to be slow when it comes to saying it is finished. There are a number of elements we must consider, such as a lack of long-period earthquakes and reduced gas emissions, so while it looks like it is settling down, we have to wait and see.”

Professor Robertson stated that the April 9 eruption was more intense than that in 1979, in that “the plumes went much higher and the explosions were more vigorous, and the pyroclastic flows travelled further than before”.

He recalled how scientists first noticed increased activity around the volcano on March 23, with “discrete shaking for about 45 minutes. That was our first moment of discomfort”.

He said: “Then on April 5, we noticed a similar more intense event and we raised our concerns with the Government at that time. On April 8, we realised the tremors were getting more serious and continuous, so with that we alerted Cabinet, and the Government moved to evacuate the affected area.

“The volcano gave clear signs of what it was doing and we got guidance that made a difference. Thanks to a combination of efforts from many different people and organisations, people managed to get out safely.”

Professor Robertson explained the four zones of risk from the volcano with the northern one-third of the island the exclusive “Red Zone”.

“The Red Zone is the area in the direct path of the volcano most likely to be adversely affected by anything coming from it; the orange, yellow and green zones are the ones further away and least likely to experience any major fallout from an eruption,” he said. The map was originally based on La Soufriere’s  May 8, 1902 eruption in which 1,680 people were killed.

When asked whether the pyroclastic flows that headed into the sea could trigger tsunamis, Director of the Seismic Research Centre, Eruscilla Joseph, told journalists: “This can only occur if a large volume of material from the volcano heads into the water, and nothing we have seen from this one so far is enough to do so. However, only this week we met with the Pacific Tsunami Warning Centre and we are planning to install a new gauge in northern St. Vincent to monitor that.” (DH)