La Soufrière Updates #70-72: Over 13,000 Displaced So Far Due To The Eruption

Significant ashfall in Owia, St. Vincent after the La Soufrière Volcano eruption. (SVG TV, April 18th, 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.

The National Emergency Management Organization (NEMO), in their 72nd update at 11:00 AM Tuesday 20th April 2021, eighty-eight (88) shelters housing 6,208 persons have been activated, and 6,567 occupying private homes have been so far accounted for. In addition, thirteen thousand, three hundred (13,303) have been displaced so far due to the La Soufrière Volcano.

In NEMO’s 70th update at 11:00 AM April 19th, 2021, they advised that the episode of continuous seismic tremor generated by explosive activity at La Soufrière Volcano lasted until about 9:00 PM on April 18th. Following this, small, long-period, and hybrid earthquakes started to be recorded again, at a rate of occurrence similar to that before the explosive activity. This rate dropped significantly at about 1:00 AM on April 19th.

In their 71st update at 8:00 PM April 19th, 2021, they added seismic activity at the La Soufrière Volcano continued the pattern established after the explosive activity Sunday evening, April 18, 2021. As of their 72nd update, small long-period and hybrid earthquakes continued to be recorded.

Over the last 36 hours, based on updates 70 through 72, No volcano-tectonic earthquakes were recorded. However, On April 19th, One rockfall was recorded at 1:39 AM. A growing lava dome can generate rockfalls, but this cannot be confirmed without visual observations. By 11:00 AM, April 20th, 2021, two rockfalls were recorded based on seismic data.

The seismic station at Bamboo Range recorded the signal from a lahar or mudflow at 4 am, which lasted for about 30 minutes. According to NEMO’s 72nd update, the lahar probably took place in one of the valleys on the southeastern flanks of La Soufrière.

The continuous GPS network has shown a change in the horizontal and vertical movement since the initial depressurization noted immediately following the April 9 explosive phase. These changes may suggest magma influx from deep within the sub-volcanic system. However, more investigation is needed to confirm this interpretation.

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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