Could the Southern Wall of La Soufriere crater become compromised?
(By Ernesto Cooke) – Professor Richard Robertson in answering such a question said in 1979; the vent was central in the crater; he says because of the obstruction of the 79 dome the vent is now south-west of the old crown.
He said most of the activity would flow in that 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”.
A lateral eruption or lateral blast is a volcanic eruption directed laterally from a volcano rather than upwards from the summit.
Breaking occurs at the flanks of volcanoes, making it easier for magma to flow outward.
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”.
Robertson further stated such an event could destroy properties in the area; however, persons would have been out of the way before it gets to that stage.
“Lateral blast tends to develop in particular ways that if we are heading in that direction, there should be indicators”, Robertson stated.
Should the dome collapse on the South Western side of the La Soufriere, it would first impact the North Leeward communities.
On Wednesday night NEMO in its latest release said scientists at the Belmont Observatory from The UWI Seismic Research Centre (SRC) have noted a change in seismic activity associated with the ongoing eruption of the La Soufrière Volcano.
Up until 23 March 2021, the seismic activity had been dominated by very small low-frequency events which were associated with the ongoing extrusion of the lava dome. These were almost always only recorded at the seismic station closest to the dome.
Starting at approximately 10:30 local time (14:30 UTC) 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.
The National Emergency Management Organisation (NEMO) wishes to inform the public that earthquakes associated with the ongoing eruption of the La Soufrière Volcano continue to occur from time to time and some of the largest ones may be felt. The alert level remains at Orange and no evacuation order or notice has been given.
However, NEMO is 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.