Persistent multitiered magma plumbing beneath Katla volcano, Iceland

Abstract

AbstractRecent seismic unrest and a persistent Holocene eruption record at Katla volcano, Iceland indicate that a near‐future eruption is possible. Previous petrological investigations suggest that Katla is supplied by a simple plumbing system that delivers magma directly from depth, while seismic and geodetic data also point toward the existence of upper‐crustal magma storage. To characterize Katla's recent plumbing system, we established mineral‐melt equilibrium crystallization pressures from four age‐constrained Katla tephras spanning from 8 kyr BP to 1918. The results point to persistent shallow‐ (≤8 km depth) as well as deep‐crustal (ca. 10 – 25 km depth) magma storage beneath Katla throughout the last 8 kyr. The presence of multiple magma storage regions implies that mafic magma from the deeper reservoir system may become gas‐rich during ascent and storage in the shallow crust and erupt explosively. Alternatively, it might intersect evolved magma pockets in the shallow‐level storage region, and so increase the potential for explosive mixed‐magma ash eruptions.