111-6 Can Magnetometry Catch Magma on the Move? A Case Study From Askja Volcano, Iceland

Session: Using Near Surface Geophysics to Investigate Geological Problems (Posters)

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Magnetometry is a powerful yet underutilized tool for monitoring temporal changes in active volcanic systems. Magnetic monitoring leverages the principle that rocks that are heated above the Curie temperature (~580 C) lose their magnetic properties and become “magnetically transparent”. Recent modeling suggests that magma migration can generate measurable changes in the crustal magnetic field. However, few in-situ datasets exist to validate these predictions, limiting the application of this method in real volcanic environments. 

Askja volcano, located in Iceland’s Northern Volcanic Zone, presents a unique opportunity to evaluate this method given its well-documented transition from decades of deflation to rapid inflation starting in August 2021. Over 0.7 meters of uplift has been recorded, with geodetic modeling of GNSS and InSAR data indicating a shallow sill-like magmatic intrusion beneath the caldera. To test the applicability of magnetic volcano monitoring, we deployed a network of fine-resolution passive magnetometers at Askja volcano in 2023. The goal of this study is to detect temporal variations in the crustal magnetic field associated with continued magma emplacement and to assess whether those changes correspond spatially and temporally with the modeled deformation source. This study addresses three key questions: (1) Can temporal variations in the crustal magnetic field reliably detect ongoing magma emplacement? (2) Do these magnetic signals spatially and temporally correspond with the modeled deformation source? And, (3) can integrating magnetic data with geodetic observations provide improved constraints on the structure and dynamics of the shallow magmatic system beneath Askja? This research explores the viability of magnetic monitoring as a complementary tool in volcano geophysics to improve real-time understanding of volcanic unrest.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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