Lava deltas, a key landform in oceanic volcanic islands: El Hierro, Canary Islands

Marine and subaerial erosion of volcanic ocean islands form coastal cliffs and shore platforms, particularly during stable sea levels. Posterosional lava flows can spill over these coastal cliffs and fill the platforms, leading to the progradation of lava deltas. This work aims to analyze this volcanic rocky coast setting at the island scale and to assess the volcanic constructional and erosive degradational effects on the coast at the scale of one volcanic edifice. El Hierro Island, Canary Islands, exemplifies a rocky coast with an active sea-cliff profile, reflecting its early evolutionary stage as a young ocean volcanic island with no fringing reef. The occurrence of a contemporary insular shelf formed during the Holocene sea-level highstand (<7 ka) allows constraining the ages of those eruptions forming lava deltas affecting this geomorphological landform. A detailed bathymetry around the island allowed us to distinguish 17 eruptions fulfilling this criterion. The Montaña del Tesoro, which occurred about 1050 years BP, is one of these eruptions and was selected as a case study for morphometric modeling integrating subaerial and submarine data at the scale of a volcanic edifice. This eruption was a Strombolian basaltic volcanic event that produced a scoria cone, pyroclastic fall deposits, and lava flows that reached the ocean in the eastern rift zone of El Hierro island. We combine field-based observations with topographic and bathymetric data analysis to reconstruct the pre- and post-eruption Digital Elevation Models (DEMs) and, comparing with present-day DEM, to analyze morphometrically the influence of volcanism on the coastal landscape's development. The resulting landform complexity required the discretization of the lava field according to the coastline evolution and lava front sectors, and the subaerial or submarine lava placement. The pyroclastic materials' total erupted bulk volume (12,829,578 m3) corresponds to a volcanic eruption index (VEI) of 3. This event was primarily effusive. From a dense rock equivalent (DRE) volume of 25,615,424 m3, 87 % flowed as lava, 10 % formed the cinder cone, and 3 % the tephra fall deposits. We quantitatively demonstrate that dominant degradation occurs in the lava field, mainly disturbed by marine erosion. Marine erosion removed 9 % of the erupted volume of lava flows against 1 % by fluvial erosion. This work provides methods and results of great interest with different implications in oceanic volcanic islands, among which we can mention coastal planning (e.g., rock coast evolution) and volcanic risk assessment (e.g., the importance of Holocene sea-level rise on the development of shore platforms facilitating the progradation of lava deltas).Grant PGC2018-101027-B-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, by the “European Union”. CPT acknowledges the PhD grant 2021 FISDU 00347 funded by the Departament de Recerca i Universitats de la Generalitat de Catalunya.Peer reviewe

Volcanes en movimiento: El Hierro y La Palma

Paneles expositivos para la divulgación del volcanismo en las islas de El Hiero y La Palma en colaboración con la Asociación Española para la Enseñanza de las Ciencias de la Tierra (AEPECT)[EN] We explain the geological history of the island of El Hierro and the 2021 eruption in the island of La Palma through a collection of ten panels. How the Canary Islands were formed and evolved is contextualized, and we introduce the birth of El Hierro. Next, we observe the landscapes of El Hierro as a response to macro-scale, such as giant landslides and rifts, and micro-scale phenomena (cones, lavas, and shore platforms). The last eruption of the island that gave rise to the Tagoro submarine volcano is also exposed. In addition, we present how the Herreños have adapted to the territory, knowing how to take advantage of its scarce water resources and adapt their way of life to the volcanic landscape, achieving that the entire island was declared in 2000 a UNESCO World Biosphere Reserve and Geopark in 2015. Finally, we expose the 2021 eruption of La Palma island.[ES] A través de una colección de diez paneles se explica la historia geológica de la isla de El Hierro y la erupción de 2021 en la isla de La Palma. Se contextualiza cómo se formaron y evolucionaron las Islas Canarias y se introduce el nacimiento de El Hierro. A continuación, se observan los paisajes herreños como respuesta a fenómenos de macroescala, como los deslizamientos gigantes y las dorsales (rifts), y microescala (conos, lavas e islas bajas). Se expone la última erupción de la isla que dio lugar al volcán submarino Tagoro. Se presenta cómo los herreños se han adaptado al territorio, sabiendo aprovechar sus escasos recursos hídricos y adaptando su modo de vida al paisaje volcánico que le rodea, consiguiendo que la isla al completo haya sido declarada por la UNESCO Reserva Mundial de la Biosfera en el año 2000 y Geoparque en el año 2015. Finalmente, se expone la erupción de 2021 en la vecina isla de La Palma.Project LAJIAL (ref. PGC2018-101027-B-I00, MCIU/AEI/FEDER, EU). Research Consolidated Groups GEOVOL (Canary Islands Government, ULPGC) and GEOPAM (Generalitat de Catalunya, 2017 SGR 1494).dc.description.tableofcontents: Filename 01: Panel01-VolcanesMovimiento-AEPECT.pdf; Filename 02: Panel02-VolcanesMovimiento-AEPECT.pdf; Filename 03: Panel03-VolcanesMovimiento-AEPECT.pdf; Filename 04: Panel04-VolcanesMovimiento-AEPECT,pdf; Filename 05: Panel05-VolcanesMovimiento-AEPECT.pdf; Filename 06: Panel06-VolcanesMovimiento-AEPECT.pdf; Filename 07: Panel07-VolcanesMovimiento-AEPECT.pdf; Filename 08: Panel08-VolcanesMovimiento-AEPECT.pdf; Filename 09: Panel09-VolcanesMovimiento-AEPECT.pdf; Filename 10: Panel10-VolcanesMovimiento-AEPECT.pdfN

Volcanoes in motion

[EN] We explain the geological history of the island of El Hierro through a collection of eight panels. How the Canary Islands were formed and evolved is contextualized, and we introduce the birth of El Hierro. Next, we observe the landscapes of El Hierro as a response to macro-scale, such as giant landslides and rifts, and micro-scale phenomena (cones, lavas, and shore platforms). The last eruption of the island that gave rise to the Tagoro submarine volcano is also exposed. Finally, we present how the Herreños have adapted to the territory, knowing how to take advantage of its scarce water resources and adapt their way of life to the volcanic landscape, achieving that the entire island was declared in 2000 a UNESCO World Biosphere Reserve and Geopark in 2015.[ES] A través de una colección de ocho paneles se explica la historia geológica de la isla de El Hierro. Se contextualiza cómo se formaron y evolucionaron las Islas Canarias y se introduce el nacimiento de El Hierro. A continuación, se observan los paisajes herreños como respuesta a fenómenos de macroescala, como los deslizamientos gigantes y las dorsales (rifts), y microescala (conos, lavas e islas bajas). Se expone la última erupción de la isla que dio lugar al volcán submarino Tagoro. Finalmente, se presenta cómo los herreños se han adaptado al territorio, sabiendo aprovechar sus escasos recursos hídricos y adaptando su modo de vida al paisaje volcánico que le rodea, consiguiendo que la isla al completo haya sido declarada por la UNESCO Reserva Mundial de la Biosfera en el año 2000 y Geoparque en el año 2015.Project LAJIAL (ref. PGC2018-101027-B-I00, MCIU/AEI/FEDER, EU)Research Consolidated Group GEOVOL (Canary Islands Government, ULPGC)Research Consolidated Group GEOPAM (Generalitat de Catalunya, 2017 SGR 1494)N

Volcanoes in motion: El Hierro and La Palma (Canary Islands)

Ten informative panels were designed to organize an exhibition of the LAJIAL project results about the recent volcanism of El Hierro Island and the 2021 eruption in La Palma Island. The format was self-rolling panels (roll-ups) 1 m wide by 2 m high, easily transportable, and highly protective. This exhibition was entitled 'Volcanoes in motion: El Hierro and La Palma' and allows us to understand that the volcanic phenomenon is very dynamic and capable of quickly changing the forms of relief, the water network, or the land use. The presentation in all these panels always keeps the same content: an upper strip including the titles of the exhibition, the thematic block, and the panel, as well as its numbering and logos of the promoting entities; a central part with much visual information in the form of maps, figures and photos accompanied by concise and easy-to-read texts; and a lower strip with the credits of the authors and logos of their institutions. The first block of panels, 'A sea of volcanoes', deals with the generation of intraplate volcanic islands, with the example of the Canary Islands (Panel 1: The Canary Islands, that is how it all began) and the geological evolution of the island of El Hierro (Panel 2: And El Hierro was born). The second block, 'Volcanic landscapes of El Hierro', focuses on geological structures on a large scale (Panel 3: Megastructures) and a small scale (Panel 4: Structures on the ground). The third block, 'Explore your volcanic paradise', pays homage to the geological maps and the last eruption on El Hierro island. Panel 5: Walking among volcanoes shows the Gorona del Lajial eruption, a true paradise of volcanic structures but a geological puzzle solved within the framework of the LAJIAL project. Panel 6: 'The last volcano' is dedicated to the eruption of the Tagoro submarine volcano. The fourth block, 'Living among volcanoes', focuses on the islander's adaptation to the volcanic territory through the rational exploitation of groundwater (Panel 7: Water on El Hierro), volcanic materials as construction elements, or the figure of the UNESCO Geopark of El Hierro (Panel 8: What the land tells us), which brings together the geology of the island with its inhabitants, promoting the sustainable development, its agricultural techniques or knowledge of its archaeological remains. The last block of two panels, 'La Palma: the pretty island' is devoted to the geological evolution of La Palma island (Panel 9: And La Palma was born) and the 2021 eruption of Tajogaite volcano (Panel 10: The eruption of 2021) that represent the last volcanic activity in the archipelago.Project LAJIAL, Grant PGC2018-101027-B-I00 funded by MCIN/AEI/10.13039/ 501100011033 and by "ERDF A way of making Europe", by the "European Union"PhD Grant 2021 FISDU 00347, Departament de Recerca i Universitats, Generalitat de CatalunyaResearch Consolidated Group GEOVOL (Universidad de Las Palmas de Gran Canaria)Research Consolidated Group GEOPAM (Generalitat de Catalunya, 2017 SGR 1494)Peer reviewe