La Soufrière Growing A New Lava Dome Following Recent Explosion

Morphological changes in the crater of the La Soufrière Volcano, St. Vincent as detected by Sentinel-1 satellite on 24th April 2021 indicative of possible growth of a dome. (Adam Stinton, UWI-SRC/MVO)

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 latest scientific advisory from the University of the West Indies Seismic Research Centre (UWI SRC), satellite radar imagery acquired on 24th April indicates probable continued growth or formation of a lava dome following the explosions on 18th and 22nd April.

Seismic activity at La Soufrière has remained low since the tremor associated with the explosion and ash venting around noon on 22nd April. In the last 24 hours, only a few long-period, hybrid and volcano-tectonic earthquakes have been recorded and there was no further tremor.

Volcano-tectonic (VT) earthquakes represent the brittle failure of rock – similar to that of tectonic quakes that occur along tectonic faults. Long-period (LP) earthquakes are caused by cracks resonating as magma and gases move toward the surface. As the name suggests, a hybrid earthquake is somewhat a mixture between a VT and an LP. They tend to have impulsive starts but also contain a significant amount of low-frequency signals. They are thought to represent magma making its way to the surface at shallow depths and are often associated with periods of rapid dome growth. 

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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