Teleseismic Scattered-Wave Imaging Using a Large-N Array in the Albuquerque Basin, New Mexico

The advent of low-cost continuously recording cable-free autonomous seismographs, commonly referred to as nodes, enables dense spatiotemporal sampling of seismic wave-fields. We create virtual source reflection profiles using P waves from five teleseismic events recorded by the Sevilleta node array experiment in the southern Albuquerque basin. The basin geology records a structurally complex history, including multiple Phanerozoic orogenies, Rio Grande rift extension, and ongoing uplift from a midcrustal magma body. The Sevilleta experiment densified the long term, regionally sparse seismograph network with 801 single channel vertical-component 10 Hz geophone nodes deployed at similar to 300 m spacing for 14 days in February 2015. Results show sediment-basement reflections at < 5 km depth and numerous sub-basin structures. Comparisons to legacy crustal-scale reflection images from the Consortium for Continental Reflection Profiling show agreement with structural geometries in the rift basin and upper crust. Comparisons of the teleseismic virtual reflection profiles to synthetic tests using 2D finite-difference elastic wave propagation show strong P-to-Rayleigh scattering from steep basin edges. These high-amplitude conversions dominate the record sections near the western rift margin and originate at the Loma Pelada fault, which acts as the primary contact between rift-bounding basement-cored fault blocks and rift basin sediments. At near offsets, these signals may interfere with interpretation of upper crustal structure, but their relatively slow moveout compared to teleseismic P-wave multiples provides clear temporal separation from sediment-basement reflections across most of the array. The high-signal-to-noise ratio of these converted Rayleigh-wave signals suggests that they may be useful for constraining short-period (similar to 1 Hz) dispersion with strong sensitivity in the uppermost similar to 1 km of the rift basin sediments.