Data consist of electron microprobe, SEM, ICP-MS in laser and solution mode, and images of crystal mounts and thin sections, La Palma 2021. 35 samples of basalt, erupted during the 2021 Cumbre Vieja eruption on La Palma, Canary Islands, were collected in February 2022. The basalt samples were prepared for various kinds of analysis: powdered for ICP-MS (whole rock trace elements including chalcophile elements), made into thin sections for petrological analysis (imaged and mapped using Scanning Electron Microscope), and crushed and crystals picked and mounted for targeted microanalysis of melt inclusions, crystals using Electron Probe Microanalysis (EPMA, for major elements and volatiles S, Cl and F) and laser ablation ICP-MS (for trace elements including chalcophile elements). The overall aim of the project was to look at the chalcophile element abundance and distribution in the magmas feeding the eruption. The data here relate to a NERC Exploring the Frontiers project.

Geochemical analyses of melt inclusions, host minerals, and glasses from the 2014-15 Holuhraun eruption, Iceland. Published in: Hartley ME, Bali E, Neave DA, Maclennan J, Halldorsson SA (2018) Melt inclusion constraints on petrogenesis of the 2014–2015 Holuhraun eruption, Iceland. Contrib Mineral Petrol 173:10. doi:10.1007/s00410-017-1435-0

Geochemical analysis of volcanic samples from Aluto, Fentale, and Kone volcanoes, Ethiopia. Data are referenced in Iddon et al., 2018: Mixing and Crystal Scavenging in the Main Ethiopian Rift Revealed by Trace Element Systematics in Feldspars and Glasses; https://doi.org/10.1029/2018GC007836.

120 samples of 57 tephra layers identified at IODP Expedition 350 sites (U1436 and U1437) were used in grain size analysis. Some layers have one grain size measurement, others have multiple measurements throughout the tephra layer.

Geochemical data has been collected on samples from new exposures of the 1883 deposits, revealed by the 2018 tsunamigenic flank collapse of Anak Krakatau, which provides improved stratigraphic context. Whole-rock data taken by X-ray Florescence shows no systematic stratigraphic correlation. Chemical data for transects across, and spot points on, plagioclase phenocrysts, including some trace element data, all obtained using Electron Probe Microanalysis (EPMA), with Backscatter electron (BSE) images of crystals, obtained using Scanning Electron Microscope, reveal complex zoning profiles. However, chemical data for transects across pyroxene phenocrysts, obtained using EPMA, show this phenocryst phase is largely unzoned. The dataset also includes chemical data for spots on Fe/Ti oxides, included on the rims of pyroxene, and obtained using EPMA. Matrix glass chemistry, obtained via EPMA, shows that the early eruptive ash is more evolved than the pyroclastic material that follows, and that there is a slight overall trend to a more homogenous, less evolved melt composition. The 1883 eruption of Krakatau was a large, cardera-forming eruption that caused approximately 36,000 fatalities. It is also the only eruption of its size to have accompanying written accounts.