Work

Seismic Imaging of the Crust From Long‐Offset Ocean‐Bottom Seismometer Data Using Time‐Domain Extended‐Source Full‐Waveform Inversion: Application to the Eastern Nankai Trough, Japan

Year: 2026

Type: article

Abstract: High‐resolution crustal‐scale seismic imaging from long‐offset ocean‐bottom seismometer (OBS) data using full‐waveform inversion (FWI) remains challenging because the large number of propagated wavelengths and waveform complexity make the inversion highly sensitive to time‐shift errors (cycle skipping). To mitigate this nonlinearity, we assess the recently developed time‐domain extended‐source (ES‐) FWI with a well‐documented OBS case study from the eastern‐Nankai subduction zone, Japan. ES‐FWI first reconstructs wavefields that fit the recorded data well using extended sources defined as the sum of the experiment and scattering sources. These scattering sources, which depend on the unknown true wavefields and the sought perturbation model, are estimated at each iteration by fitting in the least‐squares sense the associated data residuals, namely the virtually measured scattered data. The model is subsequently updated by minimizing the scattering sources, keeping the reconstructed wavefields fixed to transfer the perturbation model hidden in these sources toward the current iteration background model. This alternating‐direction optimization for wavefield reconstruction and model updating is iterated until convergence, where both data residuals and scattering sources should vanish. We perform ES‐FWI with a multiscale workflow starting from a model obtained by first‐arrival traveltime tomography. We show that ES‐FWI achieves more accurate results than FWI. Moreover, we refine the final model of the extended‐space approach by classical FWI to further decrease residual data misfit once the linear domain has been reached. Finally, several key structures resolved in the final ES‐FWI model, such as the subduction megathrust overlain by the décollement , provide a first validation of the approach.

Source: Journal of Geophysical Research Solid Earth

DOI: 10.1029/2025jb033081

Authors: Gaoshan Guo, Stéphane Operto, Jean‐Xavier Dessa

Institutions: Centre National de la Recherche Scientifique, Université Côte d'Azur, Observatoire de la Côte d’Azur, Géoazur, Institut de Recherche pour le Développement

Language: English

Topic: Seismic Imaging and Inversion Techniques

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,070

Funders: Aker BP, China National Offshore Oil Corporation, Petrobras, Grand Équipement National De Calcul Intensif