@article {chrapkiewicz_magma_2022, title = {Magma Chamber Detected Beneath an Arc Volcano With Full-Waveform Inversion of Active-Source Seismic Data}, journal = {Geochemistry, Geophysics, Geosystems}, volume = {23}, number = {11}, year = {2022}, note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022GC010475}, month = {10/2022}, pages = {e2022GC010475}, abstract = {Arc volcanoes are underlain by complex systems of molten-rock reservoirs ranging from melt-poor mush zones to melt-rich magma chambers. Petrological and satellite data indicate that eruptible magma chambers form in the topmost few kilometres of the crust. However, very few chambers have ever been definitively located, suggesting that most are too short-lived or too small to be imaged, which has direct implications for hazard assessment and modeling of magma differentiation. Here we use a high-resolution technology based on inverting full seismic waveforms to image a small, high-melt-fraction magma chamber that was not detected with standard seismic tomography. The melt reservoir extends from \~{}2 to at least 4 km below sea level (b.s.l.) at Kolumbo{\textemdash}a submarine volcano near Santorini, Greece. The chamber coincides with the termination point of the recent earthquake swarms and may be a missing link between a deeper melt reservoir and the high-temperature hydrothermal system venting at the crater floor. The chamber poses a serious hazard as it could produce a highly explosive, tsunamigenic eruption in the near future. Our results suggest that similar reservoirs (relatively small but high-melt-fraction) may have gone undetected at other active volcanoes, challenging the existing eruption forecasts and reactive-flow models of magma differentiation.}, keywords = {full-waveform inversion, Kolumbo volcano, magma chamber, magmatic system, Santorini volcanic field, volcano tomography}, issn = {1525-2027}, doi = {10.1029/2022GC010475}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GC010475}, author = {Chrapkiewicz, K. and Paulatto, M. and Heath, B. A. and Hooft, E. E. E. and Nomikou, P. and Papazachos, C. B. and Schmid, F. and Toomey, D. R. and Warner, M. R. and Morgan, J. V.} } @article {heath_relationship_2021, title = {Relationship Between Active Faulting/Fracturing and Magmatism Around Santorini: Seismic Anisotropy From an Active Source Tomography Experiment}, journal = {Journal of Geophysical Research: Solid Earth}, volume = {126}, number = {8}, year = {2021}, note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB021898}, month = {07/2021}, pages = {e2021JB021898}, abstract = {In extending volcanic arcs such as the Aegean, tectonic processes exert a significant control on magmatism. Spanning scales from 1 to 10s of km, volcanic vents, edifices, and eruptive centers follow the orientation of, and are located near, fault zones. Whether this tectonic control on magmatism results from individual faults/fractures weakening the crust or because regional stresses control magma input into the crust is debated. Here we investigate the scales of tectonic and magmatic interactions, specifically focusing on the role of local-scale (<10 km) faults/fractures in controlling magmatism. We infer local-scale fault/fracture orientations from anisotropic active-source P-wave travel-time tomography to investigate tectonic and magmatic interactions in the upper crust of Santorini Volcano, Greece, and the actively deforming region to the east. We use the anisotropy magnitude and seismic velocity reduction to model the relative distribution of both consistently oriented and randomly oriented faults/fractures. Our results show that oriented faulting/fracturing resulting from regional-scale (>10 km) tectonic stresses is distributed broadly across the region at 2{\textendash}3 km depth, approximately paralleling volcanic/magmatic features. On a local-scale, magmatism is neither localized in areas of higher oriented fault/fracture density, nor is it accommodating enough extensional strain to inhibit oriented faulting/fracturing of host rock. The alignment of magmatic features shows strong tectonic control despite the lack of correlation with local oriented fault/fracture density. These results suggest that magmatic processes are strongly influenced by regional-scale, not local-scale, tectonic processes. We infer regional processes have a greater impact on magmatism than local features due to their greater effect at depth.}, keywords = {anisotropy, faulting, magmatism, seismology, tectonism, tectono-magmatism}, issn = {2169-9356}, doi = {10.1029/2021JB021898}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB021898}, author = {Heath, B. A. and Hooft, E. E. E. and Toomey, D. R. and Paulatto, M. and Papazachos, C. B. and Nomikou, P. and Morgan, J. V.} } @article {113, title = {Body Wave Tomography of the Cascadia Subduction Zone and Juan de Fuca Plate System: Identifying Challenges and Solutions for Shore-Crossing Data}, journal = {Geochemistry Geophysics Geosystems}, volume = {21}, year = {2020}, type = {Journal Article}, abstract = {Recent seismic results from the Cascadia Initiative indicate that heterogeneity in the oceanic asthenosphere affects subduction dynamics. Accurate characterization of the oceanic upper mantle is thus necessary to fully understand subduction processes, including the behavioral segmentation of the megathrust. A key challenge is integrating onshore and offshore datasets, which span large variations in near-surface features that teleseismic body wave tomography is ill-posed to resolve. Here, we perform a series of P and S forward modeling predictions to better understand the relative contribution of elevation, crustal thickness, offshore sedimentation, and near-surface velocity structure to teleseismic delay times. Crustal thickness and elevation variations dominate the signal, contributing \~{}1 s of delay time difference for P-waves (roughly double for S). We test several inversion strategies to account for near-surface features, identifying potential artifacts and causes of imaging errors. Undamped station statics are found to absorb mantle structures and introduce low-velocity artifacts beneath the forearc. Our preferred inversion strategy utilizes a three-dimensional starting model (including elevation) of the upper 50 km and heavily damped station statics, which we find leads to better resolution of mantle structure, particularly at asthenospheric depths. These insights guide inversions of observed delay times from the Cascadia subduction zone and Juan de Fuca plate system. We present a new onshore-offshore S model and an updated P model. Major features are common to both models, including localized subslab low-velocity anomalies, along-strike variations in slab structure, and offshore heterogeneity, while regional differences may reflect changes in Vp/Vs.}, doi = {10.1029/2020gc009316}, url = {https://app.dimensions.ai/details/publication/pub.1132665170}, author = {Bodmer, M. and Toomey, D. R. and VanderBeek, B. and Hooft, E. E. and Byrnes, J. S.} } @article {Arnoux2019, title = {Seismic Imaging and Physical Properties of the Endeavour Segment: Evidence that Skew Between Mantle and Crustal Magmatic Systems Governs Spreading Center Processes}, journal = {Geochemistry, Geophysics, Geosystems}, volume = {20}, number = {3}, year = {2019}, month = {mar}, pages = {1319{\textendash}1339}, issn = {1525-2027}, doi = {10.1029/2018GC007978}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GC007978}, author = {Arnoux, G. M. and Toomey, D. R. and Hooft, E. E. E. and Wilcock, W. S. D.} } @article {Heath2019, title = {Tectonism and Its Relation to Magmatism Around Santorini Volcano From Upper Crustal P Wave Velocity}, journal = {Journal of Geophysical Research: Solid Earth}, volume = {124}, number = {10}, year = {2019}, month = {oct}, pages = {10610{\textendash}10629}, issn = {2169-9313}, doi = {10.1029/2019JB017699}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JB017699}, author = {Heath, B. A. and Hooft, E. E. E. and Toomey, D. R. and Papazachos, C. B. and Nomikou, P. and Paulatto, M. and Morgan, J. V. and Warner, M. R.} }