Seismic Imaging of the Magma Plumbing System Beneath Mount Cleveland Volcano, Alaska

Abstract:

Mount Cleveland is among the most active volcanoes in the Aleutian Arc, but sparse seismic instrumentation and a lack of mid-to-lower crustal earthquake activity has limited our ability to image the underlying crustal structure and characterize the volcano’s magma plumbing system. Teleseismic receiver functions can be used to illuminate local crustal structure without the need for distributed local seismicity. Here we harness the complementary strengths of teleseismic receiver functions and traditional seismic tomography by processing Ps-P delay times derived from receiver functions in a tomographic S wave inversion. Using our new inversion technique, we produce the most detailed tomographic crustal velocity model beneath Mount Cleveland volcano to date, with lateral heterogeneity resolved within 10 km. With this model, we identify a heterogeneous velocity structure with relatively high lateral velocity perturbations. We image a narrow, vertically extensive high V_P/V_S anomaly directly beneath the volcano that likely signifies a mid-to-lower crustal magma reservoir that may supply the persistent low level eruptive activity at Mount Cleveland. We also image several surrounding anomalies of relatively low V_P/V_S that may indicate solidified magma intrusions. These observations enhance our understanding of this highly active volcano and highlight the mid-to-lower crust as a target for imaging studies at other volcanic centers along the arc. Our technique provides a new means for advancing understanding of crustal magmatic systems in areas without broad aperture seismic networks or well-distributed local seismicity, such as ocean island volcanoes.