On the detectability of Teide volcano magma chambers (Tenerife, Canary Islands) with magnetotelluric data

Tenerife has been the subject of numerous studies covering a wide range of fields. Many studies have been focused on characterising the magmatic plumbing system. Even so, a controversy still exists regarding the location and size of the current magma chambers. Several magnetotelluric (MT) surveys have been carried out in the island, but no conductivity anomalies associated with the chambers have been detected. We report the results of a set of tests conducted against the 3-D resistivity model of the island, to determine the characteristics of the detectable chambers with the MT data. The most remarkable results indicate that the MT dataset is incompatible with a large-scale mafic reservoir located at shallower depths than 8 km b.s.l. However, shallower phonolitic chambers smaller than 3 x 3 x 1 km(3) could be undetected by the existing MT sites and new data should be acquired to confirm or not their existence. This new information is essential in volcanic islands like Tenerife, since many volcanic hazards are related to the size and depth of the sources of magma. Additionally, a joint interpretation of the obtained results together with other information is summarised in a hypothetical model, allowing us to better understand the internal structure of the island

Oxígenoterapia en el paciente crítico: lo bueno en grandes cantidades también puede ser nocivo: Girardis M, Busani S, Damiani E, Donati A, Rinaldi L, Marudi A et al. Effect of Conservative vs Conventional Oxygen Therapy. JAMA. 2017;316(15):1583–9.

La historia del oxígeno como agente terapéutico para los pacientes con enfermedades pulmonares crónicas refleja su doble papel, tanto como molécula esencial en apoyo de la vida como un oxidante agresivo de otras moléculas. El objetivo de este trabajo fue determinar si la aplicación de un protocolo de oxigenoterapia conservadora para mantener la PaO2 dentro de los límites fisiológicos podría mejorar los resultados en pacientes críticos ingresados en UCI

A 3D joint interpretation of magnetotelluric and seismic tomographic models: the case of the volcanic island of Tenerife

In this work we have done a 3D joint interpretation of magnetotelluric and seismic tomography models. Previously we have described different techniques to infer the inner structure of the Earth. We have focused on volcanic regions, specifically on Tenerife Island volcano (Canary Islands, Spain). In this area, magnetotelluric and seismic tomography studies have been done separately. The novelty of the present work is the combination of both techniques in Tenerife Island. For this aim we have applied Fuzzy Clusters Method at different depths obtaining several clusters or classes. From the results, a geothermal system has been inferred below Teide volcano, in the center of Tenerife Island. An edifice hydrothermally altered and full of fluids is situated below Teide, ending at 600 m below sea level. From this depth the resistivity and VP values increase downwards. We also observe a clay cap structure, a typical feature in geothermal systems related with low resistivity and low VP values.Comment: Preprint of the published paper without figure

El informe de arbitraje según la recomendación de publicación y la productividad de los evaluadores

El informe de arbitraje de artículos de investigación es un género en el que se cristaliza una parte del proceso colectivo de construcción del conocimiento. Debido a su carácter confidencial, existen muy pocos trabajos que aborden empíricamente este género. A su vez, esos pocos estudios tienen una serie de limitantes, como la falta de definición de la unidad de análisis y la falta de integración de los datos discursivos con los datos sociales de quienes los producen. En este trabajo, presentamos un modelo que busca superar limitantes. Aplicamos este modelo para describir cómo varía el informe de arbitraje según dos atributos extralingüísticos, la recomendación de publicación (aceptar, condicionar o rechazar) y el número de artículos publicados por los evaluadores. Los resultados muestran que ambos atributos extralingüísticos se asocian a cambios específicos del discurso de este género, siendo la recomendación de publicación más determinante que la productividad de los evaluadores.The referee report of research articles is a discursive genre in which a part of the collective process of building knowledge is crystalized. Given its confidentiality, there is little empirical work on this genre. Among these few contributions, a series of limitations can be identified, such as the lack of definition of the unit of analysis or the lack of integration between discursive and sociometric data. In this article, we present a model that contributes to overcoming these limitations. The model was applied with the purpose of analyzing the variation of referee reports according to two extralinguistic variables, i.e., publication recommendation (accepted, conditioned, rejected) and referee's number of published articles. The results showed that both extralinguistic attributes were associated with specific discourse variations, of which publication recommendation was more decisive than referee's academic productivity

Volcanic monitoring of the 2021 LaPalma eruption using long‑period magnetotelluric data

Between September and December 2021, the frst subaerial volcanic eruption in the Canary Islands in 50 years took place on the island of La Palma. Since November 2021, we have been conducting a long-period magnetotelluric (MT) monitoring experiment at a site located 2.4 km east of the volcanic cone. Having continuously recorded data since then, the obtained dataset shows signifcant changes in resistivity over the fourteen months following the eruption: more than± 20% in apparent resistivity and± 2 degrees in phase. These temporal variations in electrical resistivity, recorded continuously using long-period MT during both the syn- and post-eruptive stages, have not been reported to date, making this dataset unique. Four estimated impedances have been selected as representatives of the major temporal changes observed and inverted to generate new 3-D resistivity models. The results provide novel key information on the spatiotemporal evolution of the subsoil’s electrical resistivity, enabling the characterization of a set of structures acting as preferred magmatic fuid pathways. Therefore, our study highlights the strong potential of MT as a volcanic monitoring tool and provides new insights about the evolution of the fuid pathways during the post-eruptive stage. These fndings enhance our understanding of the magmatic system and may contribute to volcanic hazard mitigation in the future

3D electrical resistivity of Gran Canaria island using magnetotelluric data

Gran Canaria, one of the two main islands of the Canary Archipelago off NW Africa, has been volcanically active for at least 15 million years. The island went through several volcanic cycles that varied greatly in composition and extrusive and intrusive activity. The complex orography of the island has excluded extensive land geophysical surveys on the island. A review of the available geophysical information on the island shows that it has been obtained mainly through marine and airborne geophysical surveys. A new dataset comprising 100 magnetotelluric soundings acquired on land has been used to obtain the first 3D electrical resistivity model of the island at crustal scale. The model shows high resistivity values close to the surface in the exposed Tejeda Caldera that extends at depth to the SE cutting the islands in half. Outside the inferred limits of the Tejeda Caldera the 3D model shows low resistivity values that could be explained by hydrothermal alteration at deeper levels and the presence of marine saltwater intrusion at shallower levels near the coast. The presence of unconnected vertical-like structures, with very low resistivity (<10 ohm m) could be associated to small convective cells is confirmed by the sensitivity analysis carried out in the present study. Those structures are the most likely candidates for a detailed analysis in order to determine their geothermal economic potential. A comprehensive review of existing geophysical data and models of Gran Canaria island and their comparison with the new 3D electrical resistivity model is presented.</p

Imaging leachate runoff from a landfill using magnetotellurics: The Garraf karst case

Electrical and active source electromagnetic geophysical methods have been traditionally employed to approach and tackle environmental problems, such as those caused by landfills. However, since these problems are more consequential and cover broader areas, it is necessary to use deeper penetration methods, such as magnetotellurics. In the Garraf Massif (Catalan Coastal Ranges, NE Spain), an urban waste disposal landfill had been in operation from 1974 to 2006, during which more than 26 million metric tons of garbage had been deposited. This landfill overlies karstic terrain, thus principally impacting groundwater circulation. Previous electrical resistivity tomography profiles had partially imaged the infill but were not able to penetrate below the base of the original landfill. During 2019 and 2020 we performed a magnetotelluric study over the landfill and its surrounding with the goals of characterizing the electrical resistivity of the infill and below it. The 2D and 3D resistivity models confirmed the highly conductive nature of the leachate and allowed us to identify its presence below the landfill base, which we quantified with maximum thicknesses of 90 m. This proved that landfill leachate had filtered through the original impermeable layer, enhanced by the karstic drainage structure

Expected geomagnetically induced currents in the Spanish islands power transmission grids.

The aim of this study is to evaluate the geomagnetically induced current (GIC) hazard in the power networks of the Canary and Balearic archipelagos. This is done in order to strictly complete the detailed assessment at national level of the power transmission system of mainland Spain, including the 400 and 220 kV levels. We have constructed models for the grids in each of the individual systems and used resistivity models of the lithosphere for each group of islands, from which we have calculated the surface impedances. The respective models of electrical admittances of the grids have been combined with the geoelectric field derived from the convolution of the recorded (or expected in an extreme scenario) geomagnetic storms and the impedances calculated from the geoelectrical models to derive the expected GICs in the power lines, substations, and transformers. The low geomagnetic latitude of the Canary Islands combined with the small size of their power networks, makes them one of the least likely electrified locations to record significant GICs, with less than 3 A for the 100-year return period. Even the 13 A that could be reached for the upper limit of the 95% confidence interval at the 500-year return period does not seem likely to have a significant impact. The Balearic Islands, being at higher latitude and with a system length of approximately 300 km, including alternating current power lines connecting the Islands, shows GIC signals of moderate amplitude with up to 40 A for the 100-year return period.</p

Magnetotelluric applied to deep geothermal exploration:Canary Islands

Hoy día existe un interés creciente por la energía geotérmica, debido en gran parte al impulso de las energías renovables. La geotermia destinada a la generación de electricidad suele corresponder a reservorios profundos, situados por debajo del kilómetro de profundidad. Esta circunstancia condicionará los métodos geofísicos a utilizar durante la etapa de exploración del sistema geotérmico, siendo la magnetotelúrica (MT) el único método electromagnético capaz de alcanzar tales profundidades. Comúnmente utilizado en la etapa de exploración, este método aportará información sobre la resistividad eléctrica del subsuelo, y por lo tanto permitirá caracterizar lo componentes principales del sistema. Así, por ejemplo, el sello del reservorio que en muchas ocasiones está formado por una capa de arcillas producto de la alteración hidrotermal (clay cap), será fácilmente detectable con MT dada su alta conductividad eléctrica. Un referente de la aplicación de este método a la exploración geotérmica lo encontramos en las Islas Canarias, donde desde hace ya una década se vienen realizando estudios a escala regional. Los resultados obtenidos hasta la fecha, con la generación de modelos geoeléctricos tridimensionales en tres de las siete islas (Tenerife, Gran Canaria y La Palma), muestran la gran utilidad de este tipo de estudios que servirán (y ya están siendo utilizados) como base para nuevos proyectos de exploración geotérmica que se lleven a cabo en el archipiélago.</p

High-resolution scan of the Pyrenean crustal structure combining magnetotelluric and gravity data

The Pyrenees have undergone complex geodynamic evolution starting with experiencing significant tectonic events during the Variscan Orogeny, followed by the intrusion of large granitic complexes during the late Variscan stage, then the collision between the Iberian and European plates during the Alpine Orogeny, and finally, Mesozoic extension. Despite extensive studies and the application of various geophysical methods (two-dimensional seismic reflection data, gravity, and long period magnetotellurics) to investigate the Pyrenean structure, there are still fundamental questions regarding its basement and cover architecture. Specifically, the geometry at depth of significant bodies such as the Late Variscan intrusive granites and Triassic evaporitic accumulations, remains unclear. To better understand these issues, we have conducted joint magnetotelluric and gravity surveys along a 60-kilometer-long transect, spanning the boundary between the Axial and South Pyrenean Zones. Our final geological interpretation shows that the La Maladeta batholith consists of two distinct granitic bodies related to different intrusive pulses. In addition, we identify important Triassic evaporitic accumulations at depth. This work shows the high potential of integrating two geophysical models for understanding the geological evolution of structurally complex areas. The magnetotelluric and gravity data are complementary, with each dataset providing a different resolution for investigating the basement and cover architecture of the Pyrenees. These resolutions depend on the varied petrophysical properties of the rocks involved, including water content and deformation grade