Volcanic lightning observed at St. Vincent on Friday night as the La Soufrière Volcano violently erupted (Rod Stewart, UWI SRC/MVO)
|Present La Soufrière Alert Level:||ORANGE||There is a highly elevated level of seismic and/or fumarolic activity or other unusual activity. An eruption may begin with less than twenty-four hours’ notice.|
After being dormant for decades and months of unrest, the La Soufrière Volcano violently roared to life on Friday morning in a series of three explosive eruptions within 12 hours. At 8:41 AM on April 9th, 2021, a large column of volcanic ash began to rise above the La Soufrière Volcano, signaling that the volcano has moved to the anticipated explosive phase. This activity followed three months of an effusive eruption, magma extrusion within the volcano’s crater, and more recently tremors, long-period earthquakes, and volcano-tectonic (VT) earthquakes.
The eruption was also preceded by a heightened state of activity on April 8th, 2021, prompting the scientific team from the University of the West Indies Seismic Research Centre to brief Prime Minister of Saint Vincent and the Grenadines, Dr. The Honourable RalphGonsalves and his cabinet, together with the country’s National Emergency Management Organisation (NEMO). This triggered the escalation of the alert level and subsequent evacuation for the declared red and orange zones on the islands.
This first eruption of the day sent ash as high as 29,000 feet into the atmosphere and drifted hundreds of kilometers eastward. Ash drifted to the west at low levels of the atmosphere, while at mid to upper levels, ash drifted northeastward and to the east of St. Vincent. Ashfall was reported across the island of St. Vincent, with ash at upper levels of the atmosphere moving across Barbados and St. Lucia by midday.
The first emission of the day reduced visibility across St. Vincent down to 4 kilometers. It blanketed the island with a layer of hot, pulverized rock, minerals, and volcanic glass, prompting locals to say it was “raining gravel.” The ash cloud dispersed in the upper atmosphere, and final evacuations from the orange and red zones continued.
Over two thousand people have been evacuated to shelters on the island’s green and yellow zones as of Friday night. According to UWI SRC, following the first explosive eruption, seismicity increased again at 11:30 AM, with a swarm of earthquakes lasting until 2:40 PM.
The second explosive eruption occurred at 2:45 PM on Friday 9th April 2021. Most residents of St. Vincent were in the yellow and green zones of the island, where the new ash column was very visible. This second energetic eruption sent ash towering up to and in excess of 52,000 feet (nearly 16 kilometers) into the atmosphere.
This large and tall ash plume spread northeastward of St. Vincent at the mid to upper levels and westward at the low levels of the atmosphere. Based on model data, ash was expected to impact Barbados, but a shift in upper-level winds allowed the ash plume to move further northeast of the island.
Then, a third energetic eruption began at 6:35 PM on Friday 9th April 2021. This eruption also reached a height of 52,000 feet (nearly 16 kilometers). Temperatures derived from satellite data show the ash cloud’s tops, reaching temperatures of -78°C with numerous strokes of volcanic lightning within the ash cloud.
Violent venting continued into the night, with a possible fourth explosive eruption occurring between 8:20 PM and 8:40 PM based on satellite imagery. This latest plume of ash reached altitudes nearing 16 kilometers, and sustained violent venting continued into the night, with volcanic lightning ongoing. Experts warn explosive eruptions of the La Soufrière Volcano can continue for days, weeks, and even months.
The alert level of the volcano remains at red, meaning an explosive eruption is ongoing. Evacuation from La Soufrière’s Red and Orange Zones remains mandatory.
For the aviation industry, regular “Volcanic Ash Advisories” and “Significant Meteorological Information” are being issued by the Washington DC Volcanic Ash Advisory Center and the Trinidad and Tobago Meteorological Service respectively. Caribbean Airlines has canceled flights originating and landing in Barbados, as well as St. Vincent.
For mariners, an “Ashfall Advisory” is in effect for the marine waters surrounding St. Vincent and extending as far east as east of Barbados from the National Hurricane Center Tropical Analysis and Forecast Branch. Mariners are encouraged to contact the National Hurricane Center at 305-229-4424 if they encounter volcanic ash or floating volcanic debris.