16-51 Imaging Partial Melt Beneath Recent Volcanic Centers in the Cascadia Subduction Zone Backarc Using Receiver Function Analysis

Session: From Thin Section to Outcrop: Exploration of Undergraduate Research (Posters)

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The Pacific Northwest has experienced both subduction zone arc volcanism and significant backarc (intraplate) volcanism over the past ~17 Ma. The backarc volcanism has produced widespread basaltic and rhyolitic volcanism over the past ~17 Ma. This study aims to understand the distribution and storage of partial melt the crust and upper mantle beneath these intraplate volcanoes. Understanding such backarc volcanoes is important not only for the mitigation of volcanic hazards, but also for our fundamental understanding of how partial melt is generated, transported, and stored in volcanic systems. This study uses inverse receiver function analysis to investigate low-velocity and anisotropic structures that may indicate the presence of partial melt beneath several Holocene volcanic centers in southeastern Oregon, including Jordan Valley, Diamond Crater, Devil’s Garden, and Newberry Volcano. This data has been collected from broadband seismic data from USArray, the Pacific Northwest Seismic Network, the High Lava Plains network (2005-2009), and other regional networks covering these areas. The data is processed using multi-taper analysis of receiver functions, harmonic decomposition, and anisotropic layered inversions following the methodology of Link et al. (2026). This allows for the separation of isotropic velocity contrasts from signals associated with dipping interfaces and seismic anisotropy that can potentially be produced from the presence of partial melt. Results have indicated that there is a consistent prominent negative low-velocity zone that is coherent laterally beneath stations in close proximity to several backarc volcanic centers, suggesting the presence of a mid-crustal low-velocity zone that may correspond to layers of partial melt. These results will help provide new constraints on melt storage and transportation in the Cascadia backarc and geodynamical modeling of the region.

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