A mapping effort to understand variability in bending faults at subduction zones

Oceanic plates bend as they subduct at subduction zones resulting in faults termed ‘bending faults’. These faults can host large earthquakes that produce tsunamis. They also form pathways for seawater to infiltrate deep into the crust and upper mantle. This project seeks to learn why the faults vary in spacing and magnitude at different subduction zones. The investigators will map bending faults at all locations globally that have high-quality seafloor bathymetry. The results will have implications for understanding earthquake and tsunami processes and the deep water cycle. The project will provide training and research opportunities to graduate students and a cohort of undergraduate students. Bending faulting is widely recognized as an important process for 1) enabling water infiltration into subducting plates and contributing to a host of subduction zone processes and the deep water cycle and 2) modifying roughness at the top of the subducting plate with consequences for megathrust properties and forearc deformation. However, the magnitude and style of bending faulting varies within and between subduction zones. The investigators will leverage new automatic fault mapping tools to identify and characterize bending faults in multibeam bathymetry data. The global mapping will be complemented by detailed characterization of fault evolution at several locations with good seismic reflection data coverage. The results will provide fundamentally new observations on the relationships between bend faulting and plate characteristics. The data products will be shared in a format that will allow the faults to be viewed and integrated with other marine geophysical and geological data. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.