Shallow magmatic intrusion evolution below La Palma before and during the 2021 eruption

Area of Science:

• * Geophysics
• * Volcanology
• * Remote Sensing

Background:

• * La Palma, Canary Islands, experienced its largest historical volcanic eruption in 2021.
• * Volcanic unrest preceded the eruption, necessitating detailed study.

Purpose of the Study:

• * To analyze the 2021 La Palma volcanic unrest using Interferometric Synthetic Aperture Radar (InSAR).
• * To compare InSAR results with crustal structure for improved interpretation.
• * To explain the eruption's location, characteristics, and associated hazards.

Main Methods:

• * Interferometric Synthetic Aperture Radar (InSAR) data acquisition and analysis for 2021.
• * Development of an improved interpretation methodology for InSAR data.
• * Integration of crustal structure models with InSAR observations.

Main Results:

• * Identified shallow magma accumulation starting 3.5 months before the eruption.
• * Characterized the magma accumulation zone as low-density, fractured rock.
• * Successfully reproduced the final phase of volcanic unrest and detected failed eruption paths.

Conclusions:

• * The study explains the eruption's location and characteristics by linking magma dynamics to crustal structure.
• * Failed eruption paths help explain post-eruptive phenomena, including gas anomalies in La Bombilla and Puerto Naos.
• * Findings enhance understanding of Canarian volcanic activity and volcano monitoring globally, informing hazard assessment and urban planning.