A new eruption has started at Soufrière St. Vincent volcano in Saint Vincent and the Grenadines on December 28, 2020. The Alert Level was raised to Orange (3 of 4).
- Recreational visits to the volcano have been suspended.
- There might be an order to evacuate high-risk areas at relatively short notice.
- The last eruption of this volcano took place in 1979 (VEI 3).
- Much of the northern end of St. Vincent island was devastated by a major eruption in 1902 (VEI 4) that coincided with the catastrophic Mont Pelée eruption on Martinique.
On December 28, residents living near the volcano reported steam coming from the crater, prompting the National Emergency Management Organization (NEMO) to send out teams to investigate the volcano. At the same time, satellite observations confirmed thermal emissions at the crater.
NEMO team arrived on December 29, confirming that a new effusive eruption has started. Essentially, magma is now slowly coming from the earth, building a new lava dome.
Lava dome growing in the crater of La Soufriere St. Vincent volcano on December 29, 2020. Credit: NEMO
The dome is growing on the edge of the old lava dome created in 1979 — forming a dome on the rim of the dome.
The Alert Level was raised to Orange (3 of 4) around 01:00 UTC on December 30.
An Orange Level means:
- Highly elevated level of seismicity or fumarolic activity or both.
- Eruptions may occur with less than 24 hours notice.
- Monitoring system continuously manned. Regular visual inspection of potential vent areas. Continuous ground deformation and hydrothermal monitoring.
NEMO has issued a revised Volcano Hazard Map of the volcano.
Please note that Fancy and Georgetown are now in the very high hazard zone – red zone. This means that these communities will need to evacuate in the event of an eruption or pending eruption.
Volcanic Hazard Map – St. Vincent.
The map only shows hazard zone on land. However, lahars and pyroclastic falls, flows and surges will also impact areas offshore to varying degrees, and as such, the hazard zones must be envisaged as extending some distance offshore.
Hazard Zone 1 (Red Zone) – Very High Hazard:
This includes all areas expected to experience maximum damage in the short term and is the zone where all hazardous events have their greatest influence. It is defined by the zone of expected total destruction from pyroclastic flows, surges, and mudflows and by the zone of maximum expected damage from all projectiles. This zone is likely to experience more than 30 cm (12 inches) of ash. During the course of an eruption, this zone would be unsuitable for human habitation.
Hazard Zone 2 (Orange Zone) – High Hazard:
This includes all areas of moderate pyroclastic flow and surge hazard, areas within the 5 km (3.1 miles) projectile zone, and areas likely to experience between 10 and 30 cm (4 – 12 inches) of ashfall. These areas will be affected in a similar manner as Zone 1 during large scale eruptions.
Hazard Zone 3 (Yellow Zone) – Moderate Hazard:
This zone will be free from the effects of flows and surges but will be affected by 5 to 10 cm (2 – 4 inches) thick ashfalls, minor earthquakes and lightning strikes. This zone will experience significantly less physical damage than Zones 1 and 2.
Hazard Zone 4 (Green Zone) – Low Hazard:
This zone includes areas likely to be relatively safe from hazardous events, except for minor ashfall of less than 5 cm (2 inches). Crop damage and disruption of water supply due to ashfall will be the main effect but other physical damage will be minimal.
St. Vincent island on December 9, 2020. Credit: Copernicus EU/Sentinel-2, TW
Soufriere St. Vincent volcano on December 9, 2020. Credit: Copernicus EU/Sentinel-2, TW
Seismicity at the volcano started increasing on November 1, 2020, but it was considered within the normal range up until December.
"Generally events were one or two per day, sometimes none at all, but it was certainly sufficient for us to be a bit concerned and we have been liaising with NEMO ever since, providing advisories as necessary," UWI-SRC Volcanologist Dr. Richard Robertson told reporters.
The Government of Trinidad and Tobago has given permission for three staff members of the UWI-SRC, including Robertson, to travel to the volcano today, bringing with them additional instruments to enable them to more closely monitor the volcano.
Robertson said the mass growing in the crater of the volcano is similar to the one that grew in 1971/1972.
"We want to monitor the rate in which [the dome] is increasing in size because as it expands, one of the types of hazards is that it can spill over into the valleys and the closest lip it can spill over into is in the area of Larakai," Robertson said.
While there is no evacuation notice at this time, Prime Minister Dr. Ralph Gonsalves said residents north of Georgetown and Belle Isle should make plans to evacuate at short notice should that become necessary.
No prediction can be made at this time if or when the volcano will move from the effusive stage to an explosive one.
Soufrière St. Vincent is the northernmost and youngest volcano on St. Vincent Island. The NE rim of the 1.6 km (1 mile) wide summit crater is cut by a crater formed in 1812.
The crater itself lies on the SW margin of a larger 2.2 km (1.3 miles) wide Somma crater, which is breached widely to the SW as a result of slope failure.
Frequent explosive eruptions since about 4 300 years ago produced pyroclastic deposits of the Yellow Tephra Formation, which blanket much of the island.
The first historical eruption took place in 1718; it and the 1812 eruption produced major explosions.
Much of the northern end of the island was devastated by a major eruption in 1902 that coincided with the catastrophic Mont Pelée eruption on Martinique.
A lava dome was emplaced in the summit crater in 1971 during a strictly effusive eruption, forming an island in a lake that filled the crater prior to an eruption in 1979.
The lake was then largely ejected during a series of explosive eruptions, and the dome was replaced with another.
Featured image: Lava dome growing in the crater of La Soufriere St. Vincent volcano on December 29, 2020. Credit: NEMO
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