Pyroclastic flows speed down several valleys
MULTIPLE pyroclastic flows, ie flows of destruction, from a particularly large explosion at La Soufriére in the early morning of April 12, sped down several valleys.
“I would not be surprised, for example if, when we go and check this morning, that the one that went Larikai for example, probably went as far as the coastline,” Professor Richard Robertson of the University of the West Indies(UWI)-Seismic Research Centre(SRC) said in one of his daily updates on the NBC radio on Monday April 12.
He and his team, while located at the Belmont Observatory in North Leeward, have a direct view of the volcano. At approximately 4:15am, there was a big explosion and, as the material collapsed on itself it generated these 200°C to 700°C fast moving bulldozing flows down the valleys.
The material that the flows generate is incandescent and therefore glows in the night.
“ …We could see glow going down Larikai, we could see glow going down areas like Walliabou, the upper parts of Rabacca. We could see indication that there might be stuff going down valleys a little bit North of that…” the Professor explained.
The coastguard and the team of scientists headed out to sea this morning, where, from a safe distance, they scoped out the extent and direction of the flows to help them understand how the volcano is behaving now. While these flows “that happened around four o’clock this morning … were particularly fast-moving,”, flows with less energy also occurred prior to this, Robertson said.
These early morning pyroclastic flows, or pyroclastic density currents, resulted from a collapse of materials which exploded into the air, but the earlier flows, it is thought, came about because the volcano may not have had sufficieng energy to punch the materials into the air, and instead, it foamed over the top and flowed down the mountain.
The Professor disclosed that unfortunately, “because of the PDC’s(pyroclastic density currents) that happened this morning, I suspect quite a bit of the mountain now, and the communities and the buildings and the structures that are on the mountain are destroyed and damaged, mashed up.
“…I shudder to think if any living creatures were on that mountain, because anything that was there, man, animal, anything, in those PDCs, part of those PDCs, they are, they are gone. And it’s a terrible thing to say”.
The scientist further commented “…if anybody is there that survived what happened last night…I mean you don’t risk it.”
The flows have deposited material already, which means in the future, “…when it collapses, it doesn’t have a valley to keep it in the valley. So when it collapses, and when it moves down, it’s going to spread further.”
“…if the first set only went a mile, next time it collapses, the other one would go two miles. It goes further down the valley and then goes out to sea,” the scientist also said.
He advised fishermen while at sea, to stay at least three miles away from the shoreline as the order to not go north, includes by boat.
The professor pointed out that because the flows hug the mountains and there are so many mountain ranges in between the soufriere and the south, persons in the south are safe as “ simply the mountains are stopping it.” He said he hoped all persons had heeded the warning to move out of these areas.
Over the course of the morning, the National Emergency Management Organization(NEMO) warned that anyone caught in the red zone without permission will be arrested and prosecuted to the “fullest extent of the law”.
The explosive eruption phase of La Soufriere volcano is ongoing.