Relationship Between Active Faulting/Fracturing and Magmatism Around Santorini: Seismic Anisotropy From an Active Source Tomography Experiment

• Published in: Journal of geophysical research. Solid earth 2021-08, Vol.126 (8), p.n/a
• Main Authors: Heath, B. A., Hooft, E. E. E., Toomey, D. R., Paulatto, M., Papazachos, C. B., Nomikou, P., Morgan, J. V.
• Format: Article
• Language: English
• Subjects: Anisotropy; Control; Density; Depth; Distribution; Fault lines; Fault zones; faulting; Faults; Fractures; Fracturing; Geological faults; Geophysics; Lava; Magma; magmatism; Orientation; P-waves; Seismic activity; Seismic velocities; Seismic wave velocities; Seismic waves; seismology; Stress concentration; Structures; Tectonic processes; Tectonics; tectonism; tectono‐magmatism; Tomography; Travel; Velocity; Vents; Volcanic activity; Volcanic eruptions; Volcanic vents; Volcanoes
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2021JB021898

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) tectonic stresses is distributed broadly across the region at 2–3 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. Plain Language Summary Magmatic features are often preferentially located near, and share the same orientation as, faults and fractures. These faults/fractures, which weaken the upper crust, span a variety of scales from meters to 10s of kilometers. It is not clear which tectonic feature‐scale dominates the relationship between magmatic and tectonic (faults/fractures) interactions. Here we use a seismic experiment at Santorini Volcano, Greece, to investigate tectonic controls on magmatism. We use the directional dependence of seismic velocity, whether seismic waves travel faster in one direction over another, in addition to results from previous stud