Lava Tube System Development Defined by Multispectral Imaging and InSAR: The Case of the 2024 Eruption of Fernandina Volcano (Galápagos)

Abstract Lava tubes are subsurface conduits within a lava flow that feed its advance. Lava tube detection is important to understand lava flow dynamics and to mitigate geohazards. Here we use InSAR‐derived surface motion data, in combination with shortwave and thermal infrared imagery, to delineate a ∼14 km long lava tube system at Fernandina volcano, Galápagos, in 2024. The lava tubes developed during a 68‐day long eruption of basaltic lava. Individual branches of the lava tube system were mapped through a combination of: (a) spatio‐temporally stable, point‐like thermal anomalies (“skylights”) in syn‐eruption multispectral imagery; and (b) opposed, subsidence‐related, horizontal displacements defined by post‐eruption InSAR timeseries analysis. Recently elongated perpendicular baselines of the Sentinel‐1A satellite enabled estimation by InSAR of lava‐flow thickness and a lava‐field bulk volume of ∼84 ± 40 × 10 6 m 3 . Open‐channel flow transitioned to enclosed tube flow within the first 2 weeks of the eruption, once initial eruption rates of ∼7.5 × 10 6 m 3 DRE of magma per day (87 m 3 s −1 ) declined rapidly and non‐linearly to below ∼0.5 × 10 6 m 3 per day (6 m 3 s −1 ). The tube‐flow phase accounted for only 18% of the total erupted volume, but it facilitated 35% (5 km) of the total lava run‐out. Consistent with traditional field‐based observations, the remote sensing data sets illustrate the thermal efficiency of lava tube transport and its key role in the construction of shield volcanoes. Our findings also highlight the potential for multi‐sensor remote sensing approaches to inform future modeling of lava tube systems and lava flow run‐out.