Small-Scale Seismic Attenuation Structure Beneath Deep-Sea Hydrothermal Systems



Seismic velocity models of the uppermost oceanic crust are a powerful tool to constrain volcanic and hydrothermal processes at mid-ocean ridges. Application of advanced imaging and modeling techniques to mid-ocean ridge settings are producing images of seismic velocity structure beneath MORs with unprecedented detail (tens to hundreds of meters). To date, however, no study has attempted to image seismic attenuation to the same level of resolution. Intrinsic seismic attenuation is a property that is very sensitive to the presence of sub-surface fluids, as is expected to occur beneath deep-sea hydrothermal fields. Imaging the small-scale seismic attenuation structure in settings with vigorous hydrothermal activity has the potential to illuminate fluid-rich hydrothermal plumbing systems and their relationships to the geological context (e.g., faults, volcanic features).

In this project I propose to obtain high-resolution models of the sub-seafloor attenuation structure beneath a high-temperature hydrothermal field in the Mid-Atlantic Ridge. These models will be used to assess the extent to which subseafloor variations in attenuation and seismic velocity correlate with seafloor volcanic and hydrothermal features. In addition, I will perform a" series of synthetic tests to determine the best modeling strategy as well as to aid in the final geological interpretation of the models.