La Soufriere Update: Lahars at Sandy Bay, pyroclastic flows at Rabacca

By Demion McTair. Updated 7:05 a.m., Wednesday, April 13, 2021, Atlantic Standard Time (GMT-4).

The north coast of the country inundated with ashfall. Satellite imagery: Maxar Technologies

Lahars were reported in the northeastern village of Sandy Bay, while pyroclastic density currents were recorded at Rabacca on Tuesday night as explosive activities continue at the La Soufriere volcano.

According to a scientific report issued at 6:00 a.m., on Wednesday, explosions which occurred pulsed for >40 minutes and produced pyroclastic density currents (PDCs) which, appear to have gone down valleys that drain towards the Rabacca River on the east coast of the island.

Lahars (mudflows) were reported in the Sandy Bay Area on 13 April (Tuesday), the report stated.

Explosions at the volcano are likely to continue over the next few days.

The La Soufriere volcano began erupting explosively on April 9, 2021, after a sustained period of effusive eruptions which began on December 27, 2020*.

So far, there has been no report of deaths but significant damage to property and infrastructure has been reported in the north of the country.

More than 3,700 people who fled the volcanic Red Zone are in shelters, while thousands more are staying with relatives and friends.

Here is the full report:

La Soufriere, St. VIncent SCIENTIFIC UPDATE – 14/04/21 6:00AM

  1. Seismic activity at La Soufrière, St Vincent showed a similar pattern to yesterday.
  2. Small long-period earthquakes continued to gradually increase in number after the explosive activity at 6:30am on 13 April.
  3. These continued until another episode of explosive activity started at 8:30 pm on 13 April.
  4. This generated continuous seismic tremor which lasted for four to five hours.
  5. After the tremor had died down, small, long-period earthquakes were again recorded, again slowly growing
    in numbers.
  6. The explosions which occurred pulsed for >40 minutes and produced pyroclastic density currents (PDCs) which, appear to have gone down valleys that drain towards the Rabacca River on the east coast of the island.
  7. PDCs are hot (200°C-700°C), ground-hugging flows of ash and debris.
  8. Lahars (mudflows) were reported in the Sandy Bay Area on 13 April.
  9. The volcano continues to erupt explosively and has now begun to generate pyroclastic density currents.
  10. Its current pattern of explosions appears to be episodic (stop-and-go).
  11. Over the past 24 hours the time between each explosion has increased.
  12. Explosions and accompanying ashfall, of similar or larger magnitude, are likely to continue to occur over the next few days impacting St. Vincent and neighbouring islands such as Barbados, Grenada, Saint Lucia.
  13. The volcano is at alert level Red

14. Visit the International Volcanic Hazard Health Network for volcanic ash information resources: http://www.ivhhn.org/information

UWI Seismic Research Centre

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