La Soufrière’s Lava Dome Growing Wider, Longer

Visible satellite imagery showing the La Soufrière Volcano’s new lava dome growing a considerable size within the crater (Image copyright: 2021 Planet Labs Inc.)

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 latest estimates from the UWI SRC show that the new lava dome at the La Soufrière Volcano is growing at a peak rate of 2.7 m3 per second but over the long term, this growth rate is more so at 1.7 m3.

For some comparison for those who aren’t familiar with a cubic meter, the dome’s variable growth rate is between three to four times the size of a hot tub or jacuzzi per second. Another comparison would be the dome is growing up to the size of an average concrete mixer truck every 4 seconds at its peak growth rate.

Because of the crater wall and the existing 1979 lava dome, this new dome has slowed its vertical growth and is now spreading laterally along the crater rim.

How did La Soufrière get here?

According to UWI Professor Richard Robertson, speaking at the Georgetown Community Townhall, the dome was first discovered on December 27th, 2020 because of satellite imagery. Scientists were also fortunate enough to receive an image of the incipient dome due to tourists venturing up to the crater.

Time lapse of the lava dome growth at the La Soufrière Volcano. (Photos UWI SRC)
Time lapse of the lava dome growth at the La Soufrière Volcano. (Photos UWI SRC)

From December 27th, 2020 onward, according to Robertson, “we’ve had a massive mound of rock being created in the volcano. Basically, magma is coming from beneath the surface slowly onto the surface. It is becoming solid, and it’s forming a rounded mass of rock. Initially, it formed as a classic rounded shape but then as it became pressed against the sides, it has begun to move sideways essentially along the crater.”

New lava dome footprint (surface area) derived from various sources including oblique photographs, aerial photogrammetry and satellite imagery as of February 1st, 2021. (UWI-SRC/MVO, Dr. Adam Stinton)
New lava dome footprint (surface area) derived from various sources including oblique photographs, aerial photogrammetry and satellite imagery as of February 1st, 2021. (UWI-SRC/MVO, Dr. Adam Stinton)

Based on Dr. Adam Stinton’s photogrammetry work, a visiting scientist from the Montserrat Volcano Observatory, the transition from a rounded dome to a more elliptical shape is visible, caused by the new lava being bounded by the existing crater wall and the 1979 lava dome.

As of February 1st, 2021, the new lava dome has approximately 5.93 million cubic meters, spanning a length of 511 meters, a width of 231 meters and a height of 93 meters. Based on its volume, it’s about two-and-a-half times as big as The Great Pyramid of Giza. Note the Great Pyramid is still taller, at 139 meters.

Scientists continue to stress that its growth rate has fluctuated since the eruptive episode began, which is not unusual when looking at how these domes operate.

The La Soufrière's 2020-2021 Lava Dome stats as of February 1st, 2021.
The La Soufrière’s 2020-2021 Lava Dome stats as of February 1st, 2021.

Based on the latest data, Dr. Thomas Christopher, the latest team lead of the scientific team on the ground in St. Vincent, indicated that this lateral growth continues. In an interview with the UWI SRC’s Education and Outreach Manager, Stacey Edwards, on February 3rd, “we noticed over the past week and a half or so that the lateral motion actually picked up or increased relative to the vertical motion.”

He explained, “the issue is the space it has to grow; it dictates how it grows. Because we have the old dome acting as a buttress behind and a new dome has another buttress in front of it, it’s more or less squeezed in the east-west direction.” This effectively allows additional growth to occur mainly to the north and south with slower vertical growth.

“We’ve noticed is that the vertical growth would have slowed down some bit, and the growth is more laterally extensive.” Dr. Christopher reiterated that this change in growth patterns does not mean the extrusion rate has dropped. Instead, it’s still coming up and being distributed slightly differently from how it was a few weeks ago.

As of February 6th, 2021, the dome is growing faster to the north than it is to the south.

The alert level remains at Orange. The volcano continues to exude magma on the surface and steam can still be observed from the Belmont Observatory. Persons living in areas close to the volcano should expect strong sulfur smells for several days to weeks, depending on changes in wind direction.

The NEMO is reminding the public that no evacuation order or notice has been issued. NEMO continues to appeal to the public to desist from visiting the La Soufrière Volcano and especially going into the crater since doing so is extremely dangerous.

The @uwiseismic and NEMO continue to advise access to the #LaSoufriere Volcano is strictly prohibited at this time….

Posted by Trinidad and Tobago Weather Center on Thursday, January 14, 2021

According to the SRC, the new volcanic dome is extremely dangerous for those in close proximity as it can explode at any time without warning. People have been killed in this way. This warning comes as images from a birthday photoshoot surfaced on social media.

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)

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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