La Soufrière 2020/2021 Eruption FAQ
How long will the eruption last?
It is difficult to say how long this eruption will last. The length of the eruption is dependent on the amount of energy in the volcanic system. The eruption will end when there is no longer enough energy to bring material to the surface. Based on previous eruptions, the explosive may last several days to weeks.
How did it change from effusive to explosive?
Explosive eruptions are driven by volcanic gases contained in magma. During the effusive phase this gas was released slowly from the magma as it came to the surface. Eventually the pressure created by more rapidly degassing magma was too much to be contained by the material above the vent. The result is an explosive volcanic eruption. Compare it to ‘popping’ a bottle of champagne!
How does this compare to the last eruption in 1979?
This eruption appears to be larger than the 1979 eruption in terms of material put into the into the atmosphere. Its explosivity is more comparable to the 1902 eruption of the La Soufriere Volcano.
Is volcanic ash harmful?
In most persons volcanic ash will only irritate the eyes and respiratory system. Persons with pre-existing conditions like asthma will be at increased risk to be negatively affected.
Have there been any pyroclastic density currents/flows?
Yes, pyroclastic density currents (PDCs) or pyroclastic flows have been observed on the north-western flanks of the volcano. They are usually caused by the collapse of the eruption column, a dome collapse or a lateral blast.
Can lahars or mudflows be generated during and after this eruption?
Yes. There has been significant ashfall across mainland St. Vincent. With rain, ash deposits will be swept into rivers and streams forming lahars or mudflows. These flows usually have a high temperature and can carry large amounts of volcanic debris. These can happen months after the eruption has ended.
Why is there lightning in the ash column?
As the fine particles in the ash column rapidly collide there is a buildup of static electricity. We see the rapid discharge of this electricity as lightning.
Why have we not seen the orange runny lava seen in Iceland and Hawaii?
Eastern Caribbean volcanoes produce what scientists call Andesitic lavas that are very sticky. They form domes and when they erupt explosively produce lots of ash, debris avalanches and projectiles. Volcanoes like those in Hawaii produce Basaltic lavas that are very runny. These volcanoes often generate lava flows with fewer projectiles.
Now that the ash is in Barbados and St. Lucia will it also impact other islands?
Yes. Wind will carry ash further away from the volcano with time. Surface or sea level winds will carry ash west and south to the Grenadines and Grenada. In the upper atmosphere winds will take ash north and east. Islands like Martinique and Dominica may receive some ash, but the majority will go out into the Atlantic Ocean or the Caribbean Sea.
Can the current eruption cause a tsunami?
Although very unlikely at this time, small tsunamis can be generated if large amounts of material enter the sea. This large-scale movement of material can be caused by a flank collapse or lateral explosion.
Can the eruption at La Soufriere, St. Vincent trigger eruptions in the region especially at Kick em Jenny?
No, each volcano has its own plumbing system, and they operate independently. The eruption at La Soufriere cannot trigger eruptions at other volcanoes like Mt. Pelee or Kick-’em-Jenny because they are not connected.
Could the geothermal exploration trigger an eruption?
Geothermal drilling cannot trigger volcanic eruptions. Geothermal fluids (waters and gases) are produced when surface water comes into contact with rocks heated by magma. The hot fluid is extracted relatively close to the surface very far from actual magma chambers.
What do the Volcanic Alert Levels mean?
Volcanic Alert Levels allow scientists and civil authorities to quickly communicate what’s happening at a volcano. Each step up the alert level table usually indicates an increased level of volcanic activity requiring heightened awareness and action from the public.
What does the Red Alert Level mean?
This is the highest alert level. At alert level (Red) an eruption is in progress or may occur without warning. Civil authorities are continuously advised by scientists. Authorities begin or continue evacuation as necessary and issue regular radio, television and social media updates.