Practical Array Design for Multi-Mode Frequency-Wavenumber Analysis of Surface Waves

Summary

Seismic velocity profiles are crucial for exploring subsurface features and monitoring seismicity. The depth sensitivity of seismic surface waves depends on frequency and, therefore, dispersion curves, routinely obtained from frequency-wavenumber methods, are used to invert subsurface velocity structures. However, an optimal, scalable array design concept suitable for various target depths and applications remains under discussion. We propose an array design, optimised for passive seismic surveys, based on circular arrays using only the target depth range as input. Exploiting the impact of the array layout on wavenumber resolution and aliasing, we derive new relations for optimized arrays requiring only the target depth range. The concept accounts for different modes and wave types by considering penetration depth in terms of wavelength. For fundamental-mode Rayleigh waves, the maximum inter-station distance should be at least five times the maximum target depth, and the minimum distance smaller than twice the minimum target depth to avoid aliasing.