(By Ernesto Cooke) – With the 42nd anniversary of the La Soufriere Volcano eruption inching closer, the main island of St Vincent is on edge.
St Vincent’s La Soufriere volcano last erupted on April 13th 1979 and rumbled back into life in December of 2020.
This tense atmosphere is due to the recent earthquakes felt by Northern communities on the flanks of the Volcano.
The uncertainty is now whether or not the volcano will remain in the effusive state or become explosive.
In both the North-Western and Eastern communities near the Volcano, there has been some activity reminding residents that they live within the shadows of an active volcano.
There have been recent earthquakes on the North-Western side, while on the Eastern side, the pungent smell of sulphur is ever-present.
Last week NEMO stated that the Volcano activities had changed, prompting authorities to heightened emergency plans in case of a possible eruption.
Scientist monitoring the Volcano said that up until 23 March 2021, the seismic activity had been dominated by minimal low-frequency events associated with the continuous extrusion of lava reaching the surface.
These were almost always only recorded at the seismic station closest to the dome.
However, on 23 March 2021, the monitoring network recorded a swarm of small low-frequency seismic events which lasted for about 45 minutes.
These events were different from previous activity in that they were also recorded on other stations.
Scientists also stated that these events were probably associated with magma movement beneath the dome, although their depth cannot be determined.
This is the first time that such a swarm has been seen since the seismic network was upgraded in early 2021.
Starting at 16:53 local time (20:53 UTC) on 23 March 2021, the monitoring network started recording volcano-tectonic (VT) earthquakes. These earthquakes are normally associated with underground fractures of the rock mass and are commonly generated by magma pushing through an unyielding rock mass.
The volcano-tectonic earthquakes were located beneath the volcano, at depths down to 10 km below the summit. The largest of these had a magnitude of 2.6. Some of them have been reported felt by people living in communities close to the volcano such as Fancy Owia and Sandy Bay.
NEMO has since March 23rd encouraging residents especially person living in communities close to the volcano (i.e., the Red and Orange Volcanic Hazard zone), to heighten their preparedness in the event that it becomes necessary to evacuate at short notice.
Lead scientist Professor Richard Robertson said most of the activity in the crater is now flowing in the South-West direction and there is a possibility that it could compromise the crater wall.
“You can have things like a lateral blast and preferential movement in that south-west direction”, he said.
Robertson said the reasons they had place reflectors on the South Western wall were to look for potential failure in the structure.
“Now our concern was twofold, yes to look at whether the weight of the dome itself, the size of that mass of rock that is now resting on the crater wall could cause it to fail”.
Robertson said if this happens there is potential for the hot material inside the crater to get outside.
“The other thing was to monitor the stability of the South Western crater wall, both because of that kind of event and the potential for other things”.
The Geologist stated that if there were explosions from the South Western part of the crater, the possibility exists for some collapsing in that direction.
“We would hope by then; we would have alerted people in sufficient time so that no one would be in harm’s way”.
On Saturday NEMO in its latest release said The new dome continues to grow towards the Leeward and Windward sides of the Volcano with the most active gas emissions being at the top of the new dome, as well as the contact areas between the pre-existing 1979 and 2020/21 dome.
The scientist also stated on Saturday that the period of elevated volcano-tectonic (VT) earthquakes which began on 23 March 2021 stopped on March 26, 2021.
Since then, the only seismic activity being recorded are small low-frequency events associated with the growth of the dome. These kinds of events were dominant before March 23, 2021. Their rate of occurrence does not appear to have changed as a result of the volcano-tectonic earthquake swarm.
The alert level remains at Orange. The National Emergency Management Organisation 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, especially going into the crater, since doing so is extremely dangerous.