For the first time, we obtained high-resolution images of Earth's interior of the La Palma volcanic eruption that occurred in 2021 derived during the eruptive process. We present evidence of a rapid magmatic rise from the base of the oceanic crust under the island to produce an eruption that was active for 85 days. This eruption is interpreted as a very accelerated and energetic process. We used data from 11,349 earthquakes to perform travel-time seismic tomography. We present high-precision earthquake relocations and 3D distributions of P and S-wave velocities highlighting the geometry of magma sources. We identified three distinct structures: (1) a shallow localised region (< 3 km) of hydrothermal alteration; (2) spatially extensive, consolidated, oceanic crust extending to 10 km depth and; (3) a large sub-crustal magma-filled rock volume intrusion extending from 7 to 25 km depth. Our results suggest that this large magma reservoir feeds the La Palma eruption continuously. Prior to eruption onset, magma ascended from 10 km depth to the surface in less than 7 days. In the upper 3 km, melt migration is along the western contact between consolidated oceanic crust and altered hydrothermal material.

The global CO 2 discharge from subaerial volcanism has been estimated at ~300 Mt yr -1 . However, estimates of CO 2 emissions from volcanic lakes have not been considered. In order to improve this information, extensive research on CO 2 emissions of volcanic lakes worldwide has been performed. The observed normalized average CO 2 emission rates increase from alkaline (5.5 t km -2 d -1 ), to neutral (201.2 t km -2 d -1 ), to acid (614.2 t km -2 d -1 ) in volcanic lakes. Taking into account (1) normalized CO 2 emission rates, (2) the number of volcanic lakes in the world (~769), and (3) the fraction and average areas of the investigated alkaline, neutral, and acid volcanic lakes, the estimated global CO 2 emission from volcanic lakes is 117 ± 19 Mt yr -1 , with 94 ± 17 Mt yr -1 as deep-seated CO 2 . This study highlights the importance of a revision of the actual global CO 2 discharge from subaerial volcanism. Printed in USAFigure 4. Probability plot of normalized CO 2 emission rates from studied volcanic lakes. P-population.on June 3, 2015 geology.gsapubs.org Downloaded from

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