Full-Waveform Inversion for Imaging Faulted Structures: A Case Study from the Japan Trench Forearc Slope

Abstract Full-waveform inversion (FWI) of limited-offset marine seismic data is a challenging task due to the lack refracted energy and diving waves from shallow sediments, which are fundamentally required update long-wavelength background velocity model in tomographic fashion. When these events absent, reliable initial necessary ensure that observed simulated waveforms kinematically fit within an error less than half wavelength protect FWI iterative local optimization scheme cycle skipping. We use migration-based analysis (MVA) method, including combination layer-stripping approach iterations Kirchhoff prestack depth migration (KPSDM), build accurate for application on 2D with maximum offset 5.8 km. The acquired Japan Trench subduction zone, we focus area where sediments overlying highly reflective basement top Cretaceous erosional unconformity severely faulted deformed. Despite limited offsets available data, our carefully designed workflow preconditioning, building, waveform provides could improve images down almost 3.5 present several quality control measures assess reliability resulting model, ray path illuminations, sensitivity kernels, reverse time (RTM) images, KPSDM common image gathers. A direct comparison between MVA profiles reveals sharp boundary at interface, feature not be model. normal faults caused by basal erosion upper plate study reach seafloor evident subsidence strata, implying active.