«The management of the danger due to volcanic gases is frankly improvable»

«The management of the danger due to volcanic gases is frankly improvable»

The scientific coordinator of the Volcanological Institute of the Canary Islands, Nemesio Pérez. / DA/F. Pallero

The coordinator of the Volcanological Institute of the Canary Islands has been the main lookout for volcanic gases throughout the entire eruptive process of La Palma. In this questionnaire he measures his words and explains the role of Involcan in the crisis

Carmen Delia Aranda

Four months after the end of the
La Palma eruption, very high values ​​of carbon dioxide continue to be recorded in coastal areas that prevent residents from returning to their homes. To resolve our doubts, we turned to an authority on diffuse gases, the veteran volcanologist
Nemesio Perezscientific coordinator of the Volcanological Institute of the Canary Islands (

- Why can't the residents of that part of the coast return to their homes? Is there a decrease in emissions?

- Inside the ground floors (at street level) of the buildings in the Puerto Naos area, anomalous concentrations of carbon dioxide (CO2) of volcanic origin are recorded that represent a potential danger to people. In one of the monitoring stations a certain downward trend is observed, but this observation must be endorsed in other stations.

- In the volcanic building these levels are just as high? What kind of emissions are there?

- The danger of CO2 has more to do with its potential accumulation in poorly ventilated areas where it reaches relatively high concentrations that generate a decrease in the concentration of oxygen (O2) in the air. In the case of the volcanic edifice generated by this eruption, the dangerousness of the gases is more related to the presence of acidic volcanic gases such as sulfur dioxide (SO2) in the air, which requires us to wear acid gas masks to carry out research tasks inside the crater.

- Excursions are being made to the vicinity of the crater while the neighbors cannot access their farms and houses, why is this happening?

- Excursions to the vicinity of the volcanic building do not carry a risk related to the danger of volcanic gases due to the distance between the building and the closest point that visitors can access. The case of farms in Las Hoyas is very different, because in some very specific points of these farms relatively high concentrations of CO2 in the air are recorded due to the nature of CO2, heavier than air, and the existence of depressed areas topographically that favor the accumulation of CO2 despite being outdoors (outdoors). Another very different case is represented by the danger of CO2 inside homes for which there is a scientific criterion to classify the quality of the air for its habitability.

- Involcan has led the monitoring of volcanic gases throughout the eruptive and post-eruptive process. How has this work been done?

-Involcan has been the only Spanish scientific institution that carried out daily monitoring of the emission of volcanic gases, especially sulfur dioxide (SO2), from the volcanic plume through the use of miniDOAS-type remote optical sensors in a mobile land, maritime position or area; an important geochemical parameter to monitor the evolution of the eruptive process. Likewise, we were the only Spanish scientific institution to monitor the chemical composition of the gases in the volcanic plume through the use of remote optical sensors of the OP-FTIR type.

- In the area of ​​La Bombilla and Puerto Naos anomalous emanations are being registered. How are they being monitored? In which areas is the risk greater? To what extent are gases a danger?

- Anomalous concentrations of CO2 are being recorded both outside (Puerto Naos and La Bombilla) and inside buildings (Puerto Naos) which are causing a slight decrease in O2 in the air. In La Bombilla and Puerto Naos there are currently 12 CO2 monitoring stations (6 from Involcan, 4 from DGSE-GOBCAN and 2 from IGN). In these population centers there are some areas that a priori present a greater danger, but in order to carry out a more detailed zoning, Involcan plans to launch a monitoring network with 40-60 observation points inside the buildings. of Puerto Naos (ground floor at street level) whose owners want to collaborate with the Involcan to improve the management of this volcanic hazard.

-Four months after the end of the eruption, has the perception of risk decreased among the population of the Aridane Valley?

-I never tire of saying that this eruption has to mark a before and after in the management of volcanic risk in the Canary Islands, and true to this commitment, Involcan is working -in collaboration with different sectors of society- on the preparation of the 'Canarian Strategy for Volcanic Risk Reduction'. I have been saying for years that the volcanic risk in the Canary Islands is increasing.

Nemesio Pérez, on the edge of the crater, in a video broadcast by Involcan.

- What do you think of the management carried out on the danger of gases during this volcanic process?

-The management of the hazard related to volcanic gases both during level 2 and level 1 of this volcanic emergency is frankly improvable. The opinions of all those people who have expressed themselves on this matter have not been weighted as they should, and this has generated and continues to generate problems.

- In this posteruptive phase, how often does the Pevolca scientific committee meet to share data on La Palma's volcanic surveillance?

-Every 15 days at the request of the Peinpal Advisory Committee (Insular Emergency Plan of La Palma).

- Have the functions of each of the institutions participating in the committee been defined?

- Currently, the IGN is the entity that has powers over the observation, monitoring and communication of volcanic activity in the national territory and determination of associated risks, a function that has been assigned by a Royal Decree of 2004 promoted by a TAC of the General State Administration that was not agreed upon with the Autonomous Community of the Canary Islands despite the fact that volcanic risk management is a shared responsibility between the State and the Canary Islands. The rest of the institutions that are part of the Scientific Committee contribute our skills and knowledge to advise those responsible for the emergency.

After eight months advising emergency managers, how is the atmosphere in the committee? Have the rough edges arising from the underwater eruption of El Hierro?

-I prefer not to comment on this question.

- What has been the most positive and the most negative of this joint work?

- All the signs of affection and support received from the population towards our work, not only carried out during this emergency, but also the recognition of society for all those years that we have been taking the volcanoes out into the streets to contribute to the establishment of a greater culture of the prevention of the emergency in our society. Receiving the Teide de Oro 2021 award for this work fills us with pride. We are also very proud to have been the Spanish scientific institution in this volcanic emergency of greatest claim to the international scientific community, promoting the presence of 179 researchers from 70 universities and foreign scientific institutions from 20 countries.

- Will this experience serve to correct defects in the future?

- I hope and wish so, but at the same time I remember a Japanese proverb that says that a 'calamity occurs when the previous one has been forgotten'. The Involcan will be there to minimize the effect of the fragile memory of the human being.

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