New equipment detects multiple earthquakes every day at La Soufriere

Hundreds of earthquakes are taking place every day at La Soufriere and the new dome has grown to over 80 metres in height.

Scientists monitoring the volcano now have access to this type of detailed information because of new equipment installed recently at the summit of the volcano and elsewhere.

Speaking on NBC radio’s Face to Face programme on Monday January 25, volcanologist Professor Richard Robertson said his team has installed a Continuous Global Positioning System (CGPS) station at the Richmond Vale Academy and an Electronic Distance Measurement (EDM) reflector camera at the summit of the volcano.

An EDM instrument is a surveying instrument for measuring distance electronically between two points through electromagnetic waves.

The CGPS monitors changes in the shape of the mountain prior to an eruption, while the EDM reflector camera has been placed on the southern crater wall of the volcano and is pointed straight at the dome to help them detect any changes in its shape.

Robertson however noted that there are still some communications issues to deal with, in order for the camera to have 100 per cent functionality.

Robertson leads a team from the Seismic Research Centre, University of the West Indies (UWI-SRC) St Augustine Campus.

He said his team is looking at the southern crater wall to determine whether it is becoming compromised by the new dome which is pressing on it.

The gas and other material coming out of La Soufriere are also being monitored and Robertson said the material coming out to the south of the crater is affecting the old dome.

The volcanologist noted also that they were helped by a local drone operator, so they have photos and video footage which is helping track the shape and other developments at the volcano.

He noted also that the daily earthquakes have moved from one or two per day to “couple 100”, but most of them cannot be felt and is only being picked up by their equipment. As the dome expands southward, the breaking rocks are shaking the ground and creating gas.

“That is to be expected,” Robertson said while adding that they are looking at the number of earthquakes and type of rocks and that will tell them what is coming out of the volcano, so they will be better able to use that information to advise the National Emergency Management Organization (NEMO).

He noted also that it is possible that rocks may fall on the old dome and bury it as rock falls are happening all the time, some 1.6 cubic meters per second in some instances.

As at January 18, the new dome was approximately 350 meters spreading northwest to southeast and 180 meters the other way. The height was at 80 to 90 meters above the crater floor and Robertson said the new dome will get longer faster than it will get higher.

The UWI professor noted also that sometimes, there are landslides from the crater walls especially when there is heavy rainfall, and those rocks are sometimes hot and they burn the surrounding vegetation.

“Not much vegetation [is] holding up the inner crater wall so I am not surprised if we have landslides and rock falls off the crater itself,” Robertson added.

He said the leaves of the vegetation are turning brown and reddish brown, but the root systems of the trees and grass are still there, so the soil is not being affected.

He said the soil will remain safe unless there is a fire which kills trees and strips the land like in a type of slash and burn method.

“If the dome comes over the lip of the crater rim it has the potential of hot rock going down,” he noted while revealing that the hot rocks started a fire there a few weeks ago.

The scientist noted that if the dome gets above the crater rim, rocks will fall over the edge and into the valleys and they and consideration is being given as to how that will affect communities on the south western side of the volcano.

Michelle Forbes, Director of NEMO is again pleading with persons not to destroy the equipment.