On 19 September 2021, a new monogenetic volcano (Tajogaite) erupted on the Island of La Palma (Canary Islands, Spain). After 85 days of Strombolian style eruption, with emissions of volcanic material, a pyroclastic cone 200 m high and 800 m in its basal diameter was formed. Successive lava flows descended the western slopes and reached the Atlantic Ocean on 29 September. On descending the coastal cliffs and entering the sea, the lava flows formed two lava deltas on the submarine island shelf, backed by fossilized coastal cliffs. This geological event has raised a new challenge: the environmental conservation of new volcanic landscapes in island territories with high anthropogenic pressure on land uses. This work uses comparative and numerical methods in geoheritage to support their conservation from a scientific basis. In a first phase, a cartographic inventory was made of all the volcanic formations similar to the new volcano in the geological framework of the Canary Islands. In a second phase, their representativeness (A), rarity (R), diversity (D), integrity (I), and observability (O) were quantitatively measured by means of dimensional estimators. The results obtained show that the new volcano presents a geological value of the first order in the context of the Canary Islands, which is one of the most prominent oceanic archipelago worldwide. Its value is based above all on its high conservation state with respect to the similar volcanoes in the Canary Islands. The high mismatch found between the intrinsic geological value and the environmental protection of this area, justifies the development and application of urgent basic guidelines for its protection, as well as the promotion of geotourism as opposed to alternative land uses.

The analysis of the historical documentary sources together with evidence from the geological record is essential to understand the impact and processes triggered by tsunamis on the Canary Islands. This archipelago has been affected by tsunamis caused by different geological processes, of which the most studied have been those generated by prehistoric mega-landslides. However, there is also evidence of those produced by distant tsunamigenic sources. An exhaustive review of all documentation available was made, identifying the existence of at least four seismically triggered tsunami episodes (1755, 1761, 1941 and 1969), the majority with an epicenter in the Azores-Gibraltar boundary. In this work, several tsunamis are cited for the first time, such as the one produced by the Argaga (La Gomera) landslide in 2020. Other episodes historically identified as tsunamis are discarded as they corresponded to other geological events. The effects of most historic tsunamis have gone unnoticed, having occurred in epochs of sparsely populated coastal areas. But their study allows us to infer the need for the archipelago authorities to establish preventive measures to avoid possible damage from tsunamis, especially if we consider the presently high population density of the Canarian littoral.

This study examines the role of North Atlantic storms degrading a Late Pleistocene rocky shoreline formed by basaltic rocks overlying hyaloclastite rocks on a small volcanic peninsula connected to Gran Canaria in the central region of the Canary Archipelago. A conglomerate dominated by large, ellipsoidal to angular boulders eroded from an adjacent basalt flow was canvassed at six stations distributed along 800 m of the modern shore at El Confital, on the outskirts of Las Palmas de Gran Canaria. A total of 166 individual basalt cobbles and boulders were systematically measured in three dimensions, providing the database for analyses of variations in clast shape and size. The goal of this study was to apply mathematical equations elaborated after Nott (2003) and subsequent refinements in order to estimate individual wave heights necessary to lift basalt blocks from the layered and joint-bound sea cliffs at El Confital. On average, wave heights in the order of 4.2 to 4.5 m are calculated as having impacted the Late Pleistocene rocky coastline at El Confital, although the largest boulders in excess of 2 m in diameter would have required larger waves for extraction. A review of the fossil marine biota associated with the boulder beds confirms a littoral to very shallow water setting correlated in time with Marine Isotope Stage 5e (Eemian Stage) approximately 125,000 years ago. The historical record of major storms in the regions of the Canary and Azorean islands indicates that events of hurricane strength were likely to have struck El Confital in earlier times. Due to its high scientific value, the outcrop area featured in this study is included in the Spanish Inventory of Geosites and must be properly protected and managed to ensure conservation against the impact of climate change foreseen in coming years.