Low-Frequency Signal Reconstruction and Imaging of Land Nodal Passive Source Based on Seismic Interferometry: A Case Study Using I-Nodal Data from a Western Work Area
摘要
Nodal passive seismic acquisition has gained significant attention in geophysics for its cost efficiency, environmental advantages, and operational flexibility. However, effectively utilizing low-frequency signals from such data remains a challenge. While passive source imaging has been widely applied in shallow engineering and deep crustal studies, its adoption in conventional seismic production remains limited. This study extends passive seismic imaging to production-scale data, establishing a complete processing workflow for constructing synthetic shot gathers via seismic interferometry using three days of continuous I-Nodal recordings from a terrestrial survey in western China. The workflow includes mean removal, detrending, and normalization to enhance data quality, followed by cross-correlation-based interferometry to generate synthetic shot gathers. Key factors such as virtual source location, recording duration, and node count were analyzed to optimize reconstruction, with phase-weighted stacking applied to strengthen coherent signals. Finally, after noise suppression was applied to the synthetic shot gathers, prestack time migration imaging was achieved, demonstrating that passive data provide rich low-frequency information capable of imaging both shallow and mid-depth structures effectively. These results highlight the potential of nodal passive source imaging as a valuable complement to conventional active-source methods.