Magmatic plumbing and dynamic evolution of the 2021 La Palma eruption

Abstract

The 2021 volcanic eruption at La Palma, Canary Islands, was the island’s most voluminous historical eruption. Little is known about this volcano’s feeding system. During the eruption, seismicity was distributed in two clusters at ~10-14 km and ~33-39 km depth, separated by an aseismic zone. This gap coincides with the location of weak seismic swarms in 2017-2021 and where petrological data have implied pre-eruptive magma storage. Here we use seismological methods to understand the seismic response to magma transfer, with 8,488 hypocentral relocations resolving small-scale seismogenic structures, and 156 moment tensors identifying stress heterogeneities and principal axes flips. Results suggest a long-lasting preparatory stage with the progressive destabilisation of an intermediate, mushy reservoir, and a co-eruptive stage with seismicity controlled by the drainage and interplay of two localised reservoirs. Our study provides new insights into the plumbing system that will improve the monitoring of future eruptions in the island.

Late complex tensile fracturing interacts with topography at Cumbre Vieja, La Palma

“…During the period we ob-served the occurrence of the fracture set, also shallower earthquakes were identified. In fact, a comparison to available seismic catalogues [del Fresno et al 2023] * reveals a chronologic succession, with large earthquakes at the deeper reservoirs at 34 and 12 km depths, followed in the end of November 2021 and early December 2021 by more shallow earthquakes at <12 km depth, which is followed by the new eccentric crater on the northern flank of the main eruptive crater and then by the divergent fracture on the southern side as described in our work. In this view, the vertical time lag between earthquake and eruption changes is less than one day, whereas the horizontal time lag between the northern vent and the fracture emergence in the south is up to four days.…”

Lithospheric Sill Intrusions and Present‐Day Ground Deformation at Rhenish Massif, Central Europe

“…Possible implications for magma propagation and future eruptions based on our volume growth rate can be inferred from Galetto et al (2022), who found that magma volume increase in crustal reservoirs at rates <0.01 km 3 /yr have not led to magma propagation in 90% of cases. The magma supply episodes analyzed by Galetto et al (2022) were located in the middle-to-upper crust, so in the RHM case the eruption likelihood would be lower, but still deserves attention, as magma may ascend relatively swiftly from large depths (e.g., Mayotte and Cumbre Vieja, La Palma, eruptions; Cesca et al, 2020;del Fresno et al, 2023).…”

“…The magma supply episodes analyzed by Galetto et al. (2022) were located in the middle‐to‐upper crust, so in the RHM case the eruption likelihood would be lower, but still deserves attention, as magma may ascend relatively swiftly from large depths (e.g., Mayotte and Cumbre Vieja, La Palma, eruptions; Cesca et al., 2020; del Fresno et al., 2023).…”

Evidence of a Low‐Velocity Zone in the Upper Mantle Beneath Cumbre Vieja Volcano (Canary Islands) Through Receiver Functions Analysis

“…We consider that this area is affected by partial melting due to the very low Vs values. Even if the RF method we used in this work lacks sufficient spatial resolution, previous seismological studies (D'Auria et al, 2022;Del Fresno et al, 2023) demonstrated the presence of at least two magmatic chambers located within the LVZ. This finding is corroborated by petrological (Klügel et al, 2000(Klügel et al, , 2005 and gravimetric studies (Montesinos et al, 2023 postulated that the precursory seismicity recorded between 2017 and 2021 indicated that the subcrustal chamber was fed, through repeated magmatic transfer episodes, by the lower magmatic chamber, located at about 25 km depth (represented by a solid ellipse in Figure 3).…”