Hundreds of Earthquakes Detected on La Soufrière

Earthquakes recorded by the University of the West Indies Seismic Research Centre (UWI SRC) at La Soufrière as of January 26th, 2021. (UWI SRC)

Present La Soufrière Alert Level:YELLOWThe La Soufrière Volcano is restless. Seismicity and/or fumarolic activity are above the historical level at the volcano, or other unusual activity has been observed. This unusual activity will be specified at the time that the alert level is raised. This is level two of four.

Earthquake activity associated with the eruption of La Soufrière was low at the outset – likely due to most quakes registering between micro- to minor magnitudes.

As of January 16th, 2021, the UWI SRC reported that from the beginning of 1st November 2020, the SRC recorded 121 seismic events at La Soufriere, with one or two earthquakes a day and a maximum of eleven volcanic earthquakes recorded on 16th November 2020.

Two of the earthquakes recorded to date have been larger than magnitude 2.0, at magnitude 2.3 and 2.5, which occurred on 12th and 14th December. The largest so far, at magnitude 3.3, was recorded at 10:29 PM on 16th December 2020.

According to Professor Richard Robertson, speaking at the Georgetown Town Hall on January 26th, 2021, he explained earthquakes are always associated with volcanic activity.

Earthquakes recorded by the University of the West Indies Seismic Research Centre (UWI SRC) at La Soufrière as of January 26th, 2021. (UWI SRC)
Earthquakes recorded by the University of the West Indies Seismic Research Centre (UWI SRC) at La Soufrière as of January 26th, 2021. (UWI SRC)

“We’ve always had periods when you’ve had more earthquakes than normal. At La Soufrière, you generally tend to have one or two periods when you have one or two [events] per month, sometimes one or two [events] per day.”

“When looking at seismicity from 2019 to the present, the period where volcanic unrest is clear. “it has had a lot more so you’ve had periods where you’ve had tens [of earthquakes] rather than one or two events per day. That’s kind of normal. You go up, and you come down.”

However, as more and more monitoring stations increased across St. Vincent, additional seismic events were being registered. Since the installation of a seismic station on the 6th January on the flanks of the volcano at Wallibou, and the one at the summit, on the 18th January, 573 earthquakes have been recorded, up to 7:30 AM 30th January 2021.

There are now seven seismic stations streaming data to the Belmont Observatory in St. Vincent and the UWI SRC’s base in St. Augustine, Trinidad.

Should you be concerned about La Soufrière’s quakes?

Even with these hundreds of earthquakes being recorded, residents in St. Vincent, particularly those near the dome of the volcano, may not have felt a single shake to date. This is because of the small magnitude of the quakes so far.

According to Dr. Thomas Christopher, in an interview with the UWI SRC’s Education and Outreach Manager Stacey Edwards on February 3rd, 2021, he explained that there is a combination of more seismic events occurring and more events are beginning recorded because of the increase in equipment.

“Most people would have known that since January 1st, there are a lot more instruments operating on the island than there were at the end of last year. It could be a function that we’re seeing more events or there are actually more events happening.”

Seismic equipment being checked along the flanks of the volcano. Photo credit: Prof Robertson

Posted by UWI Seismic Research Centre on Monday, January 18, 2021

He explained that this increase in seismicity is normal for periods of volcanic unrest. “If there are more events happening, it’s not unusual because you would expect to see that as an eruption unfolds.” However, he reiterated that the recorded events are so small, it is not even felt by those who are working on the crater. “The events are quite tiny from the field teams, or anyone who’s working with us has never felt any of these events on the summit.”

Dr. Christopher explained, “I would think that they’re not much cause for concern at the moment. There are definitely more of them at the moment, but it could be a function of we’re able to see them better, or there’s actually more of them.”

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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