5:15 PM - 7:15 PM
[SSS04-P01] Locating ocean microseism sources using seismic observations in the Caribbean region
Keywords:ocean microseisms, source location and direction
Oceanic microseisms represent the most energetic signals in the seismic ambient noise spectrum. Their sources are explained by two mechanisms: interactions between ocean waves and interactions between ocean waves and the seafloor topography. Their most distinctive features are two spectral peaks: the primary microseisms, at the same frequency of the generating ocean waves and secondary microseisms (SM) at twice the frequency of the ocean waves that generate them.
Seismic ambient noise used in seismic interferometry and seismic tomography often contains signals within the ocean microseisms frequency range (0.05-0.33 Hz). Some of these seismic processing techniques assume an isotropic distribution of ambient noise sources, however, in practice, ambient noise sources change location with frequency and season. Therefore, information about the location of ambient noise sources is essential to select the appropriate processing method and to ensure an accurate interpretation of the results.
The source locations of ocean microseisms in the Caribbean region have never been explored, and those in semi-enclosed seas have been investigated to a lesser extent compared to open oceans. The first analysis on ocean microseisms source characteristics in the Caribbean Sea has been done by Poveda Brossard et al. (2025). They estimated the source directions and intensities for the Rayleigh and P waves in the SM frequency range, using recordings of broadband seismic stations from the Cuban seismic network. This study aims to extend the work of Poveda Brossard et al. (2025) by locating the sources of ocean microseisms using seismic stations across the Caribbean region. Additionally, our research focuses on the location of ocean microseisms sources in the Caribbean, a region with relatively stable and weak sources that have been less studied so far.
To locate ocean microseisms detected by seismic stations in the Caribbean we processed seismic data from stations surrounding the Caribbean Sea focusing on the Rayleigh waves at 4-8s. To achieve this, we first applied polarization analysis, using the cross-spectral ratio between the vertical and horizontal velocity components (e.g., Takagi et al., 2018) to determine the dominant backazimuths of the Rayleigh waves, as well as the strength of the wave field in those directions. We also incorporated some of the backazimuths previously estimated by Poveda Brossard et al. (2025) using the same polarization method. Second, we used the estimated backazimuth and intensities to infer the locations of ocean microseism sources. Our analyses are ongoing, focusing on determining the dominant locations of ocean microseism sources of Rayleigh waves at 4-8s in the Caribbean and assessing their temporal stability to better understand microseism generation in semi-enclosed seas.
Seismic ambient noise used in seismic interferometry and seismic tomography often contains signals within the ocean microseisms frequency range (0.05-0.33 Hz). Some of these seismic processing techniques assume an isotropic distribution of ambient noise sources, however, in practice, ambient noise sources change location with frequency and season. Therefore, information about the location of ambient noise sources is essential to select the appropriate processing method and to ensure an accurate interpretation of the results.
The source locations of ocean microseisms in the Caribbean region have never been explored, and those in semi-enclosed seas have been investigated to a lesser extent compared to open oceans. The first analysis on ocean microseisms source characteristics in the Caribbean Sea has been done by Poveda Brossard et al. (2025). They estimated the source directions and intensities for the Rayleigh and P waves in the SM frequency range, using recordings of broadband seismic stations from the Cuban seismic network. This study aims to extend the work of Poveda Brossard et al. (2025) by locating the sources of ocean microseisms using seismic stations across the Caribbean region. Additionally, our research focuses on the location of ocean microseisms sources in the Caribbean, a region with relatively stable and weak sources that have been less studied so far.
To locate ocean microseisms detected by seismic stations in the Caribbean we processed seismic data from stations surrounding the Caribbean Sea focusing on the Rayleigh waves at 4-8s. To achieve this, we first applied polarization analysis, using the cross-spectral ratio between the vertical and horizontal velocity components (e.g., Takagi et al., 2018) to determine the dominant backazimuths of the Rayleigh waves, as well as the strength of the wave field in those directions. We also incorporated some of the backazimuths previously estimated by Poveda Brossard et al. (2025) using the same polarization method. Second, we used the estimated backazimuth and intensities to infer the locations of ocean microseism sources. Our analyses are ongoing, focusing on determining the dominant locations of ocean microseism sources of Rayleigh waves at 4-8s in the Caribbean and assessing their temporal stability to better understand microseism generation in semi-enclosed seas.