Detection of Seismic Core Phases from the Northern Atlantic Cyclones on the Australian Spiral-Arm Arrays

Abstract

Microseisms, generated due to continuous harmonic forces by the ocean waves, represent a crucial source of seismic data. Although array techniques effectively detect microseismic signals, especially with dense large-aperture arrays, identifying low-amplitude, core-sensitive body-wave phases remain challenging and particularly rare in the southern hemisphere. The challenge of detecting microseismic core phases is intensified by overlapping with stronger, more pervasive surface-wave signals from proximal microseismic sources. Here, we investigate the feasibility of using small-aperture arrays with a spiral-arm design deployed at multiple locations in Australia. We observe energetic arrivals in secondary microseisms during the northern hemisphere winters and identify the core-sensitive seismic phases from the distant storms in the North Atlantic Ocean. We infer the character and geographic distribution of the sources generating these body-wave signals using the Capon and backprojection methods. We present the observations of distinct PKP branches from the southern tip of Greenland and Newfoundland basin, within the 4–6 s period band. Our findings highlight the efficacy of small-aperture spiral arrays in isolating core-sensitive signals from distant storm activity, with possible future implications for studying the Earth’s interior.