The dangerous pyroclastic density currents (flows) were observed on the eastern and western flanks of the volcano, the UWI SRC Team said. Pyroclastic flows are fast moving flows of lava, ash and hot gases which burn anything in their path.
Volcanologist/geologist Professor Richard Robertson from the University of the West Indies in an update regarding the explosive phase of the eruption while on NBC radio, explained that the pyroclastic flows are one of the most dangerous things that the volcano can do, and it is one of the things that killed people during the 1902 eruption.
Sometimes at 200 km per hour, faster than a person or vehicle, the flows move down the volcano. It is not able to predict which direction they will collapse down the mountain.
“…In front of it there’s a wave of finer ash called a surge. If you think of a hot, heavy wind. So you have a heavy part that’s in the main part and then you have a wind that’s stretching out to the front and to the side. And above it you have a rising column of ash just like in the plumes,” the Professor disclosed.
When it reaches the ocean, “…they would boil the sea and they would shoot across the sea as a foam of rapidly moving hot air and they will scald anything in their way.”
They will burn boats, and anyone in the area would have to try and move at least one mile out to sea.
“…there are stories from 1902 where people who were offshore the Walliabou river when the pyroclastic flows came down, they were actually offshore too close and so they jump into the sea and they tried to dive and the water above them was boiling,” Robertson relayed.
“We don’t have lava flows, the nice slow runny things that’s red and glowing, we don’t have those things here. What we have is fragments of rock and boulders and other things that shoot down the mountain very fast and destroys everything,” Robertson stated.
La Soufriere began explosive eruptions on Friday, after springing back to life in December 2020 with effusive eruptions.
Robertson says says new eruptions are expected which may be larger than those that occurred in 1979. A previous eruption in 1902 killed some 1,600 people.
Robertson noted that prior to Friday’s eruption, La Soufriere’s dome had a volume of 13 million cubic meters of magma, all of which were thrown into the atmosphere by the eruption creating a large hole in the crater.
The Vincentian government on Thursday issued a mandatory evacuation order for residents in areas in the north of the island, close to the volcano. and part of an island chain that includes the Grenadines and home to more than 100,000 people.
Some 20 thousand residents of this so-called Red-Zone are expected to be moved to some 62 government shelters,shelters and other temporary accommodation in the southern part of the island. Several neighbouring East Caribbean Islands have offered to accommodate some of the evacuees.
The explosive eruptions which have caused islandwide power outages and water lock-offs, have deposited a heavy ash cover over most of St. Vincent and the Grenadines.
Neighbouring Barbados has also received heavy ash deposits, and Prime Minister Mia Mottley has announced today as the start of a national clean-up, urging Barbadians to clear up the ash from around their homes and properties. Smaller ash deposits were also reported in Grenada and Saint Lucia.
The Caribbean Community of Nations, CARICOM, on Saturday offered to help by shipping emergency supplies or temporarily opening their borders to the roughly 16,000 evacuees fleeing ash-covered communities.
Prime Minister Ralph Gonsalves urged Vincentians to remain calm, have patience and keep protecting themselves from the coronavirus.
He observed that so far, there were no reported deaths or injuries from the volcano’s eruption noting that “agriculture will be badly affected, and we may have some loss of animals, and we will have to do repairs to houses, but if we have life, and we have strength, we will build it back better, stronger, together,” Gonsalves said. He observed it could take up to four months for life to return to normal.
- Countries: St_Vincent_Grenadines