SPECTRAL RELATIONSHIP BETWEEN OCEAN WAVES AND MICROSEISMIC NOISE: A DYADIC ANALYSIS USING TE-GRAM

Understanding the coupling mechanisms between ocean dynamics and ambient seismic noise remains a fundamental challenge in Earth system science. This study introduces a high-resolution spectral analysis between seismic signals and ocean waves using the Te-gram, a mathematical tool designed to overcome the limitations of classical time-frequency methods. Two local seismic events near Baja California, occurring on April 22, 2021 (Mw 3.8) and September 15, 2022 (Mw 4.1), were analyzed, along with wave acceleration data from CDIP station 155. The results reveal persistent energy peaks centered at 0.07 Hz in both marine and seismic records, consistently observed across multiple time windows. This frequency aligns with the primary microseism band and is indicative of direct seafloor interactions driven by long-period ocean swell. Comparative analysis with conventional spectral tools demonstrates the Te-gram superior ability to suppress cross-terms, resolve localized energy, and preserve nonstationary signal features. Control period comparisons further reinforce the hypothesis that enhanced wave energy in the microseismic band corresponds with increased seismic energy at the same frequency, suggesting continuous ocean–solid Earth energy transfer. These findings contribute to the geophysical understanding of how persistent oceanographic conditions can influence the lithosphere’s background oscillations.