Theoretical Solution and Applications of Ocean Bottom Pressure Induced by Seismic Seafloor Motion

• Published in: Geophysical research letters 2017-10, Vol.44 (20), p.10,272-10,281
• Main Authors: An, Chao, Cai, Chen, Zheng, Yong, Meng, Lingsen, Liu, Philip
• Format: Article
• Language: English
• Subjects: Bottom pressure; Displacement; Earthquakes; focal mechanism; Gauges; Measuring instruments; Ocean bottom; ocean bottom pressure; Ocean bottom seismometers; Ocean floor; Oceans; Parameter estimation; Pressure; Pressure gages; Pressure gauges; Pressure sensors; Seismic activity; seismic waves; Seismographs; Seismometers; Sensors; tsunami warning; Tsunamis
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2017GL075137

Seismic signals captured by ocean bottom pressure sensors, which are designed to record tsunami waves, are largely ignored. In this paper, we derive a simple theoretical solution of the ocean bottom pressure as a function of prescribed seafloor motion. All the assumptions are clearly stated and analyzed. The solution is checked by comparing the seafloor displacement and pressure from three M7+ earthquakes, recorded by ocean bottom seismometers and pressure gauges located off the Japanese coast. We then show two applications. First, using the seafloor displacement data recorded by an ocean bottom seismometer, the pressure amplitude recorded by the associated pressure gauge is corrected, and vice versa. Second, pressure recordings from Deep Ocean Assessment and Reporting of Tsunamis during the 2011 Tohoku earthquake are converted to seafloor displacements, which are then utilized to estimate the earthquake focal mechanism. Thus, we demonstrate that seismic signals recorded by pressure sensors have great potential for fast estimate of earthquake source parameters. Key Points We derive the theoretical equation of ocean bottom pressure induced by seismic waves propagating on seafloor The equation is checked using observations of three earthquakes recorded by ocean bottom seismometers and pressure gauges The equation has two applications: correction between seafloor displacements and pressure and estimate of focal mechanism using pressure data