Abstract Recent studies have challenged the classical view of magma chambers as ephemeral, melt‐rich bodies confined to shallow depths beneath arc volcanoes at subduction zones. Instead, increasing evidence supports the existence of long‐lived, vertically extensive magmatic systems with persistent partial melts within the crust. Nevertheless, the depth and extent of crustal magma reservoirs remain poorly constrained. We use 549 P‐wave receiver function events at station AV.WACK and 223 at AV.WAZA to image the crustal structure beneath Mt. Wrangell in southcentral Alaska. We identify a prominent low‐velocity layer in the lower crust, approximately 4–9 km thick and 40 km wide, and a narrower low‐velocity layer at shallower depths. These observations suggest a large lower‐crustal magma chamber containing 9%–33% melt and a localized shallow reservoir with ∼10% melt, supporting the existence of a long‐lived, multi‐layered magmatic system. Our findings provide critical constraints for evaluating and monitoring volcanic hazards in this region.

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