Ambient noise source localization by cross-component cross-correlations

The spatial distribution and characteristics of ambient seismic noise sources critically influence the reliability and accuracy of ambient noise interferometric imaging, a widely used technique for subsurface characterization. A novel localization method was proposed based on the similarity of cross-component Rayleigh wave cross-correlation functions. Unlike conventional approaches that rely on the assumption of retrograde particle motion of Rayleigh waves, our method eliminates such prerequisites, enhancing robustness and applicability in complex wavefields with multiple surface wave modes, especially higher-order modes that often exhibit prograde motion. Comprehensive synthetic simulations demonstrated accurate resolution of source backazimuths under various scenarios, including multisource configurations and disparate source energy ratios, outperforming two existing methods in terms of accuracy and robustness. Field data from a dense seismic array deployed on a university campus confirmed the method’s effectiveness in capturing persistent traffic-related sources and time-varying active sources. By integrating localization results to selectively extract data from the stationary phase zone, surface wave dispersion imaging quality was enhanced and artifacts from off-line and incoherent sources were suppressed. The method also mitigates near-station effects caused by localized, noncoherent energy that often degrades interferometric stability. This method provides a more stable and reliable framework for ambient noise source localization, advancing the practical application of ambient noise interferometry.