UWI SRC La Soufrière Update: Multiple Earthquakes, Rockfalls & Lahars Being Recorded

Lahar at the Rabacca Dry River, St. Vincent after the La Soufrière Volcano eruption. (SVG TV, April 12th, 2021)

Present La Soufrière Alert Level:ORANGEThere 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.

According to the University of the West Indies Seismic Research Centre’s (UWI SRC) latest scientific advisory issued at 6:00 PM Tuesday 20th April 2021, seismic activity at the La Soufrière Volcano continued the pattern established after the explosive activity on 18 April.

The Centre continues to record small long-period, hybrid, and volcano-tectonic earthquakes, with the seismic also recording a few rockfalls. No seismic tremor has been recorded in the last 12 hours. In the past, seismic tremors are associated with explosive eruptions of the La Soufrière Volcano.

UWI SRC is also measuring sulphur dioxide flux along the west coast of St. Vincent with the assistance of St. Vincent and the Grenadines Coast Guard. Measurements today yielded an average SO2 flux of 350 tons per day.

Since the initial depressurization noted immediately following the April 9th explosive phase, the continuous GPS network has recorded a decrease in the overall rates of horizontal and vertical movement.

In their earlier advisory, at 6:00 AM, the seismic station at Bamboo Range recorded the signal from a lahar (mudflow) at 4:00 AM, which lasted for about 30 minutes and may have flown along a valley on the southeastern side of the volcano. The SRC added two rockfalls were also recorded.

Volcanic Hazard Map for the La Soufrière Volcano, St. Vincent (UWI SRC/NEMO)
Volcanic Hazard Map for the La Soufrière Volcano, St. Vincent (UWI SRC/NEMO)

According to the UWI SRC, the volcano continues to erupt. Its pattern of seismic activity over the last few days is typical of the growth and destruction of lava domes. Explosions with accompanying ashfall, similar to or larger, can occur with little or no warning impacting St Vincent and neighboring islands.

The alert level remains red. The National Emergency Operations Center continues to be fully functional operating on a twenty-four-hour, around-the-clock basis. NEMO will continue to provide regular updates as they continue to monitor the Volcano.

Official information will originate from St. Vincent and the Grenadines National Emergency Management Organization and the University of the West Indies Seismic Research Center.

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