Utilizing Diffractions as a Tool to Study the Volcano-Tectonic Processes at the Christiana-Santorini-Kolumbo Volcanic Field

The interplay between volcanism and tectonics gives rise to a spectrum of geological phenomena, including eruptions, earthquakes, mass failures, and tsunamis, posing significant threats to both local and global environments. Seismic data interpretation serves as a crucial tool for reconstructing past volcanic-tectonic interactions, offering insights into potential precursors and triggers for future events. However, the inherent complexity of volcanic-tectonic regions often poses challenges for seismic imaging and interpretation, particularly regarding the delineation of faults, as well as the identification of volcanic structures, volcanic products, and mass transport events.

In this study, we explore the frequently overlooked diffracted wavefield as a tool to aid seismic interpretation of volcano-tectonic structures. Wave diffraction occurs at geodynamically important features like faults, erosional surfaces or other small-scale scattering objects and encodes information on a sub-wavelength resolution. Our approach models and adaptively subtracts the reflected wavefield from the un-migrated seismic data before we focus the separated diffractions to generate diffraction-energy images. We will present two seismic profiles from the Christiana-Santorini-Kolumbo volcanic field, one of the most active volcano-tectonic fields in Europe. These profiles cross major rift basins, complex fault zones, volcanic edifices, and mass-transport deposits. Our derived diffraction images provide a unique window into the subsurface, highlighting important small-scale heterogeneities. We observe that diffractions cluster at geodynamically important subsurface structures, such as faults, volcanic cones, as well as distinct unconformities within the rift basins. Diffractions also cluster at seismic subunits previously interpreted as eruptive products such as ignimbrites and lava flows, as well as mass-wasting deposits. In contrast, we observe that little diffraction occurs in sedimentary strata interpreted to be the result of hemipelagic background sedimentation. Thus, this study strongly advocates for the integration of diffraction energy images into the standard practice of seismic data analysis and interpretation in the context of volcano-tectonic interactions.