Shihao Yuan, Felix Bernauer, Joachim Wassermann, Eileen Martin, Heiner Igel

Determining the direction of seismic waves is crucial for many applications, from monitoring natural hazards like avalanches and landslides to detecting nuclear explosions and conducting surveillance. Traditional methods rely on arrays of seismic sensors arranged in specific patterns, but deploying these arrays can be challenging or impossible in many environments, such as cities, ocean floors, mountains, or other planets. We present an alternative solution: a single-station system that measures six-component (6C) ground motions to determine the direction of seismic sources. Using a collocated seismometer and rotational sensor, we simultaneously record both translational and rotational ground motions to determine the direction of vehicle sources from a single 6C station. The 6C approach not only maintains a small footprint but also extracts directional information from both Rayleigh and Love waves. We validate our method by comparing results from different types of rotational sensors and conventional array-based techniques, including frequency-wavenumber analysis and array-derived rotation. Our findings confirm the 6C method's capability to accurately locate vehicle sources while offering advantages over traditional array deployments, particularly in challenging environments where multiple sensor installations are impractical. The successful application to traffic monitoring demonstrates the method's potential for broader applications, including real-time seismic monitoring and geohazard early warning systems. This advancement in seismic source tracking methodology opens new possibilities for urban and environmental seismic noise analysis.