F. J. Perez-Torrado’s research while affiliated with University of Las Palmas de Gran Canaria and other places

The 2021 La Palma eruption (Tajogaite) was unprecedented in magnitude, duration, and degree of monitoring compared to historical volcanism on La Palma. Here, we provide data on melt inclusions in samples from the beginning and end of the eruption to compare the utility of both melt and fluid inclusions as recorders of magma storage. We also investigated compositional heterogeneities within the magmatic plumbing system. We found two populations of olivine crystals: a low Mg# (78–82) population present at the beginning and end of eruption, recording the maximum volatile contents (2.5 wt % H2O, 1,800 ppm F, 700 ppm Cl, 3,800 ppm S) and a higher Mg# (83–86) population sampled toward the end of the eruption, with lower volatile contents. Despite their host composition, melt inclusions share the same maximum range of CO2 concentrations (1.2–1.4 wt %), indicating olivine growth and inclusion capture at similar depths. Overall, both melt and fluid inclusions record similar pressures (450–850 MPa, ∼15–30 km), and when hosted in the same olivine crystal pressures are indistinguishable within error. At these mantle pressures, CO2 is expected to be an exsolved phase explaining the similar range of CO2 between the two samples, but other volatile species (F, Cl, S) behave incompatibly, and thus, the increase between the two olivine populations can be explained by fractional crystallization prior to eruption. Finally, based on our new data, we provide estimates on the total volatile emission of the eruption.

Damage and destruction caused by the 2021 eruption of the Tajogaite volcano on La Palma was unprecedented relative to other historical eruptions of the last century (1909, 1949, 1971, 2011) in the Canary Islands. The devastation caused by the eruption was not a result of eruption magnitude, which was only marginally larger than other historical events, but instead an increasing vulnerability due to population growth and increasing rural land use on the slopes of the volcanically active Cumbre Vieja Ridge. Since future eruptions along the Cumbre Vieja are inevitable, it is imperative that actions are taken to ensure the safety of the island's growing population. While civil protection and emergency services managed to avert loss of life from direct volcanic impacts in 2021, loss of property for many people in the affected area remains a grave issue and requires targeted measures to safeguard against human suffering from similar future events.

This dataset collects the petrographic description of 64 lava flow and pyroclast samples from the Holocene eruptions investigated on the island of El Hierro (Canary Islands, Spain) in the LAJIAL Project (PGC2018-101027-B-I00). The project was developed at the Univer- sity of Las Palmas de Gran Canaria, the GEO3BCN (CSIC), the University of Barcelona, and the University of La Laguna. The petrographic description of each sample includes a location map of El Hierro Island, a picture of the outcrop, a general view of the thin section, and general information about the sample. The geographic location of samples in the maps on page 2 is linked to the corresponding sample petrographic data, and in turn, clicking the location of the sample on the location map accompanying the petrographic data, the user returns to the general maps on page 2.

This dataset includes 28 photographs illustrating the stratigraphic relationships among the 27 eruptions out of 42 Holocene eruptions on the island of El Hierro (Canary Islands), investigated within the LAJIAL Project (PGC2018-101027-B-I00). The Project was developed at the University of Las Palmas de Gran Canaria, the GEO3BCN (CSIC), the University of Barcelona, and the University of La Laguna. Within the same Project, we delivered a previous dataset focused on the petrographic features of the Holocene volcanism of El Hierro island (Prieto-Torrell et al., 2024a). The stratigraphic relationships among the Holocene eruptions are based on field observations, applying stratigraphic and geomorphological criteria as the overlapping of lava flows from different eruptions or the surroundings of lava flows to previous volcanic cones and lava fields. For the isolated eruptions or not observed stratigraphic relationships (12 eruptions), the chronostratigraphic control is limited for radiometric ages or the formation of coastal lava deltas (Carracedo et al., 2001; Rodriguez-Gonzalez et al., 2022). A simplified geological map introduces the main features of El Hierro Island, whereas a second map (page 3) shows the four detail areas used to organize the images. The identification numbers (ID) and names of eruptions are according to Prieto-Torrell et al. (2024b). Each of these detail areas contains a link that leads to the corresponding detail map, with which the section of its images begins. Similarly, the detail maps incorporate a clicking button that returns to the general map of page 3. Inside the detailed maps are located icons of a photo camera (with the orientation in which the photographs were taken) linked to the corresponding photograph that illustrates a specific stratigraphic relationship. Each photograph incorporates a clicking button that returns to the corresponding detail map. The coordinates of the point where the photograph was taken are indicated on each photo. Furthermore, contacts are marked with dashed lines, and the flow direction of lava flows is indicated with arrows. Each photo is accompanied by a brief explanation denoting the eruptions involved.

Fuerteventura and Lanzarote (Eastern Canary Islands), form the oldest emerged part of the archipelago. Geologically, they can be considered a single edifice, constituting a continuous volcanic ridge extending 250 km from SW to NE. This work completes the dating and the determination of the magnetic stratigraphy of the shields and the rejuvenated volcanism of Fuerteventura and Lanzarote, refining the volcanic stratigraphy and cartography. The new unspiked K-Ar ages and magnetostratigraphy of Fuerteventura and Lanzarote indicate that these islands developed patterns similar to those of the Central and Western Canary Islands, building adjacent and successively superimposed basaltic shield volcanoes during the Miocene, between 20.19 ± 0.30 and 6.30 ± 0.11 Ma. The overlay of post-Miocene rejuvenated volcanism hinders the extent and interrelationship of the shields. These materials constitute only a small fraction by volume but cover a large part of the islands. Despite this, it is confirmed that the disposition of the shields is opposite to the insular progression induced by the hot spot, suggesting the presence of some SW-NE propagation volcanic front or fracture to explain its direction of development. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6641464

The 2021 La Palma eruption provided an unpreceded opportunity to test the relationship between earthquake hypocenters and the location of magma reservoirs. We performed density measurements on CO2-rich fluid inclusions (FIs) hosted in olivine crystals that are highly sensitive to pressure via calibrated Raman spectroscopy. This technique can revolutionize our knowledge of magma storage and transport during an ongoing eruption, given that it can produce precise magma storage depth constraints in near real time with minimal sample preparation. Our FIs have CO2 recorded densities from 0.73 to 0.98 g/cm3, translating into depths of 15 to 27 km, which falls within the reported deep seismic zone recording the main melt storage reservoir.