Swell-driven bursts of 26 s and 16 s seismic spectral peaks in the Gulf of Guinea

The interaction between the atmosphere, hydrosphere, and solid Earth can result in the generation of complex seismological signals, offering significant insights into remote and enigmatic physical processes. Among these signals, the persistent narrow-band seismic energy observed in the Gulf of Guinea remains unexplained. Initially thought to reflect merely the propagation of oceanic swells, these signals have more recently been linked to the interaction between the ocean and the solid Earth. However, the quantitative relationship between oceanic activity and the occurrence of these signals remains unproven, and the underlying generation mechanism is not fully understood. In this study, we quantitatively explore the relationship between bursts of seismic energy and the passage of swells generated by distant storms in the Southern Ocean. Through an interdisciplinary analysis of seismological data, ocean wave models, and satellite altimeter data, here we report spatial, frequency and time-dependent patterns that suggest seismic signals may be associated with resonance cracks dynamically triggered by swell activity. The study suggests that long-period seismic bursts are triggered by ocean swell through the activation of cracks and fluid movement in the crust, linking wave activity in the Gulf of Guinea to episodic seismic energy release.