Physical Characterization of Long‐Lasting Hybrid Eruptions: The 2021 Tajogaite Eruption of Cumbre Vieja (La Palma, Canary Islands)

• Published in: Journal of geophysical research. Solid earth 2022-11, Vol.127 (11), p.n/a
• Main Authors: Bonadonna, Costanza, Pistolesi, Marco, Biass, Sébastien, Voloschina, Marija, Romero, Jorge, Coppola, Diego, Folch, Arnau, D’Auria, Luca, Martin‐Lorenzo, Alba, Dominguez, Lucia, Pastore, Camille, Reyes Hardy, Maria‐Paz, Rodríguez, Fátima
• Format: Article
• Language: English
• Subjects: ash dispersal; ash forecasting; Ashes; Atmospheric conditions; Dispersion; Dynamics; Emission; Emissions; eruption classification; Forecasting; Geophysics; Islands; Lava; Lava flows; Local winds; Magma; Plumes; Tephra; tephra cones; tephra deposits; Tremors; Volcanic eruptions; Wind
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2022JB025302

Long‐lasting, hybrid eruptions can be of complex description and classification, especially when associated with multiple eruptive styles and multiple products. The 2021 Tajogaite eruption of La Palma, Canary Islands, was associated with a magma‐gas decoupled system that resulted in the simultaneous emission of lava flows and tephra plumes from various vents. Even though the tephra blanket (∼2 × 107 m3) represents only 7%–16% of the total erupted volume, it provides fundamental insights into the overall eruptive dynamics. Tephra was mostly dispersed NE‐SW due to a complex regional and local wind patterns and was subdivided into 3 units and 11 layers that well correlate at different distances from the vent and with both tremor data and lava emission rate. While plume height varied at the temporal scale of a few hours, the average mass eruption rate associated with the tephra blanket of the different units remained relatively constant (∼3–4 × 103 kg s−1). In contrast, the emission rate of lava largely increased after the first week and remained higher than the overall emission of tephra throughout the whole eruption (average value of ∼6 × 104 kg s−1). Based on a detailed characterization of the tephra blanket in combination with atmospheric wind, tremor, and lava emission trend, we demonstrate the need of (a) multidisciplinary strategies for the description of hybrid eruptions that account for both the duration of individual phases and the quantification of the mass of multiple products, and of (b) dedicated ash dispersal forecasting strategies that account for the frequent variations of eruptive and atmospheric conditions. Plain Language Summary Volcanic eruptions are mostly subdivided into effusive and explosive when they are associated with the emission of lava flows or with the fragmentation of magma that results in the generation of widespread deposits (i.e., tephra). The September–December 2021 Tajogaite eruption of La Palma Island (Spain) represents a typical example of long‐lasting, hybrid eruption with alternation, or, more often, contemporaneous emission of lava flows and tephra. The lava field extended toward the western sector of the island, while the tephra blanket was mostly dispersed NE‐SW due to a complex regional and local wind pattern. Even though the tephra blanket represents only 7%–16% of the total erupted volume, it provides fundamental insights into the overall eruptive dynamics. Based on a detailed characterization of the tephra blank