Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 20 explosive eruptive events registered over the past two centuries. Recent eruptions (1967, 1969, and 1970) and the volcanic unrest episodes that happened in 1992, 1999, and 2014–2015 demonstrate that the occurrence of future volcanic activity is a valid and pressing concern for scientists, technical and logistic personnel, and tourists, that are visiting or working on or near the island. We present a unifying evolutionary model of the magmatic system beneath Deception Island by integrating new petrologic and geochemical results with an exhaustive database of previous studies in the region. Our results reveal the existence of a complex plumbing system composed of several shallow magma chambers (≤10 km depth) fed by magmas raised directly from the mantle, or from a magma accumulation zone located at the crust-mantle boundary (15–20 km depth). Understanding the current state of the island’s magmatic system, and its potential evolution in the future, is fundamental to increase the effectiveness of interpreting monitoring data during volcanic unrest periods and hence, for future eruption forecasting.

Almost exactly half a century after the eruption of the Teneguía Volcano on La Palma (26 October to 28 November 1971), a new eruption occurred on the island and lasted for 85 days from 19 September until 13 December 2021. This new eruption opened a volcanic vent complex on the western flank of the Cumbre Vieja rift zone, the N‐S elongated polygenetic volcanic ridge that has developed on La Palma over the last c. 125 ka. The Cumbre Vieja ridge is the volcanically active region of the island and the most active one of the Canary Islands, hosting half of all the historically recorded eruptive events in the archipelago. The 2021 La Palma eruption has seen no direct loss of human life, thanks to efficient early detection and sensible management of the volcanic crisis by the authorities, but more than 2800 buildings and almost 1000 hectares of plantations and farmland were affected by lava flows and pyroclastic deposits. Satellite surveillance enabled accurate mapping of the progressive buildup of the extensive and complex basaltic lava field, which together with monitoring of gas emissions informed the timely evacuation of local populations from affected areas. Lava flows that reached the sea constructed an extensive system of lava deltas and platforms, similar to events during earlier historical eruptions such as in 1712, 1949 and 1971. Long‐term challenges in the aftermath of the eruption include protection of drainage systems from potential redistribution of tephra during high rainfall events, the use of the large surplus quantities of ash in reconstruction of buildings and in agriculture, and the crucial concerns of where and how rebuilding should and could occur in the aftermath of the eruption. Finally, there remain strong financial concerns over insurance for properties consumed or damaged by the eruption in the light of future volcanic hazards from the Cumbre Vieja volcanic ridge.

Effusive eruptions dominate the eruptive record of many arc volcanoes and may hold crucial information about their plumbing systems, yet they are underrepresented in geochemical and petrological studies. Here, we present whole rock major and trace element data as well as Sr-Nd-Hf isotopic compositions for 14 lavas and deposits of 4 Plinian eruptions of the Popocatépetl Volcanic Complex (PVC) in the last ∼23.5 ka, allowing the first comprehensive geochemical characterisation of the dynamics and evolution of its plumbing system. Lavas and pumices of the PVC are andesites-dacites with a narrow compositional range showing no first-order geochemical trends in the last ∼23.5 ka. Trace element and isotope ratios show that PVC magmas are derived from a depleted mantle source with a component of subducted sediments. Assimilation-fractional crystallisation models show that magma compositions are modified to varying degrees by assimilation of lower and upper crust en route to the surface. In the shallow plumbing system, geochemically distinct magmas coexist and undergo extensive mixing and hybridisation, thus buffering erupted whole rock compositions. Only few flank eruptions sample more primitive magmas from deeper reservoirs that circumvented the shallow plumbing system. Some Plinian eruptions caused compositional shifts reflecting reconfigurations of the plumbing system, which also affected subsequent effusive eruptions. Our study thus shows that the geochemical variability of PVC magmas in the last ∼23.5 ka is dominated by crustal processes, and magma hybridisation is the primary mechanism to produce the buffered whole rock compositions of the PVC. Resumen El estudio de la geoquímica de roca total de elementos mayores y trazas, así como composiciones isotópicas de Sr-Nd-Hf, de 14 coladas de lava y 4 depósitos de erupciones plinianas de los últimos ∼23,5 ka del Complejo Volcánico del Popocatépetl (CVP) nos han permitido hacer por primera vez una caracterización geoquímica integral de la dinámica y evolución de su sistema magmático. Estos datos indican que las lavas del CVP presentan un rango composicional limitado sin variaciones geoquímicas significativas durante los últimos ∼23,5 ka, que los magmas se originan en un manto empobrecido con un componente de sedimentos subducidos, y que son modificados en distintos grados por asimilación de corteza inferior y superior en su ascenso hacia la superficie. Además, muestran que en el sistema magmático somero coexisten magmas geoquímicamente diferentes que se mezclan e hibridizan eficientemente antes de su erupción, amortiguando así variaciones en las composiciones de roca total que son emitidas. Algunas erupciones de flanco muestrean magmas más primitivos de reservorios más profundos que rodearon el sistema magmático somero. Finalmente, algunas erupciones plinianas causaron modificaciones composicionales que afectaron las erupciones efusivas siguientes y que reflejan reconfiguraciones del sistema magmático.

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 CO 2 -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 CO 2 recorded densities from 0.73 to 0.98 g/cm 3 , translating into depths of 15 to 27 km, which falls within the reported deep seismic zone recording the main melt storage reservoir.