Theoretical Solution and Applications of Ocean Bottom Pressure Induced by Seismic Waves at High Frequencies

Previous studies have demonstrated that the ocean‐bottom pressure associated with seismic seafloor motion is linearly proportional to the vertical seafloor acceleration, for frequencies much lower than the resonance frequency of water layer (c0/4h, c0 water sound speed, h water depth). In this article, we use realistic observations to verify a theoretical relation between the ocean‐bottom pressure and vertical acceleration up to the water resonance frequency. We then show two applications of the theoretical relation. First, the pressure amplitude recorded by differential pressure gauges is calibrated, and the calibration coefficient is found to vary by frequency. Second, Rayleigh wave phase velocity near the water resonance frequency can be calculated from recordings of pressure and vertical seafloor acceleration at a single station, which is useful to constrain the shallow Earth structure. Plain Language Summary In ocean‐bottom seismology, traditional studies only use the recordings of vertical seafloor deformation because horizontal seismic measurements generally suffer from bad quality due to ocean‐bottom currents. Therefore, to image the Earth structure, research methods often require data from a station array, that is, multiple stations with small distances. In this study, we use realistic observations to demonstrate that the ocean‐bottom pressure and vertical seafloor acceleration satisfy a theoretical relation up to the resonance frequency of water layer. Based on the theoretical equation, a method is developed to derive the Rayleigh wave phase velocity using recordings of pressure and seafloor deformation. The method is applicable to data at a single station, and it is suitable to constrain shallow Earth properties. This study implies that it is worth exploring the usage of ocean‐bottom pressure of high frequencies in seafloor seismology. Key Points We verify a theoretical solution between ocean‐bottom pressure and vertical seafloor acceleration by real observations The solution is used to calibrate differential pressure gauge data, and the calibration coefficient is found to vary by frequency Rayleigh wave phase velocity near the water resonance frequency can be derived from pressure and acceleration recorded at a single station