Timon .:. | Thu, September 30, 2021 | 0
La Palma volcanic activity could last for weeks or months, which is “normality” for a volcanic archipelago
The Canarian Seismic Network managed by the Canary Islands Volcanological Institute (Involcan) report having been able to detect more than 20,650 earthquakes in the Cumbre Vieja volcano, on the island of La Palma, between 1:00 a.m. (Canary time) on Friday, September 10 just before this latest event began, and 7:00 p.m. (Canary time) this Thursday evening.
On Friday Involcan reported that most of them are so small that it has not even been possible to locate them and at times there have been more than 400 earthquakes detected per hour.
The director of Spain’s National Geographic Institute (IGN) in the Canary Islands, María José Blanco, said this Friday morning that the Cumbre Vieja volcano, on La Palma, “is very energetic” but also less explosive than both, Teneguía, which last erupted exactly 50 years ago in October and November of 1971, and San Juan back in 1949, yet in just four days the Cumbre Vieja has released the same amount of energy as was produced over two months during the recent Tagoro submarine volcano, off the coast of El Hierro ten years ago, in 2011.
In an interview with ‘Radio Canarias’ reported by Europa Press, Blanco commented that a daily estimate of magnitudes is made following the evolution of seismic processes they are monitoring and “it cannot be ruled out” that “stronger” earthquakes could be felt over the coming days or weeks.
She said that whether an eruption will take place is “absolutely unpredictable”, as is when or where it might come from, and although she admitted that “concern is growing” about the impact that a volcanic eruption might have, in her view the situation must be seen as part of the Canary Islands’ “normality” as a volcanically active archipelago.
Blanco pointed out that, unlike past volcanic eruptions on the island, the population has “more information and more training” about what is happening and “there is no surprise” when a process of this type is triggered, though previous such episodes may well have ended with twenty or more fatalities.
“Many died of fear,” she said, since they were unaware of the existence of a seismovolcanic crisis.
Blanco described the current process as “an entry of magmatic material that fills the pores, melts them and advances” and if there is finally an eruption there will be more material, although she also stressed that “It doesn’t have to erupt either.”
In fact, “knowing if the crust will break, is the million dollar question”, she said, recalling that on El Hierro there was a lot of seismicity, a lot of energy release events and a lot of deformation “but they did not last long and did not reach the surface.”
On El Hierro the seismic activity began in the El Golfo valley yet the eruption ended up going south and into the sea. “It advanced tens of kilometres”, she commented.
She has also said that “it cannot be ruled out” that the volcanic process, started on La Palma, “will last for many months” because the islands are active volcanic terrain and there will be more eruptions “in the future”. “They can be prolonged in duration, be very short, you have to normalise the situation,” she stressed.
The PEVOLCA scientific committee have maintained the yellow alert, despite a decrease in activity at Cumbre Vieja, on La Palma
The Scientific Committee for the Special Plan for Civil Protection and Attention to Emergencies due to Volcanic Risk (PEVOLCA), met this Friday, and verified a decrease in seismic activity, but insisted that the scenario may be transitory and does not imply a stoppage of volcanic reactivation.
They recommended that the Directorate maintain a Yellow Alert in the Cumbre Vieja area, on La Palma, in the municipalities of Fuencaliente, Los Llanos de Aridane, El Paso and Mazo, intensifying surveillance and monitoring tasks. The Scientific Committee, as well as the Steering Committee, will meet again this Saturday.
In their report they indicate that over the last few hours a clear decrease in seismic activity has been observed, although a pulse of notable intensity has been recorded, with localised events, both at depths of 6-8 km, and on the surface. Today’s seismicity is located NE of that of the previous day. Shallow seismicity is found to be predominant. The deformation continues at a lower speed, being compatible with a more superficial source of deformation.
The process continues and may evolve rapidly in the short term. The decrease in seismicity may be temporary and does not necessarily imply a stoppage of volcanic reactivation.
As already indicated in their previous bulletin, the occurrence of felt earthquakes of greater intensity is expected. The beginning of observable phenomena on the surface cannot be ruled out.
The scientific committee has also commented on the choice of some news media outlets having to explore a supposed likelihood of a major collapse of the west flank of Cumbre Vieja, with a subsequent formation of a “mega tsunami”, by simply pointing out that there is no data to support this hypothesis and that it lacks any proven scientific basis.
The Scientific Committee is coordinated by the General Directorate of Security and Emergencies of the Government of the Canary Islands and is made up of representatives of the National Geographic Institute (IGN), Higher Council for Scientific Research (CSIC); The Canary Islands Volcanological Institute (Involcan), the Geological and Mining Institute of Spain (IGME), the State Meteorological Agency (AEMET), the Spanish Institute of Oceanography (IEO), the University of La Laguna and the University of Las Palmas de Gran Canaria.
PEVOLCA, this Friday, also studied evacuation plans with the La Palma Cabildo, in preparedness for any further developments