Oliveira Tiago C. A.

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Tiago C. A.

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  • Article
    Pressure field induced in the water column by acoustic-gravity waves generated from sea bottom motion
    (John Wiley & Sons, 2016-10-24) Oliveira, Tiago C. A. ; Kadri, Usama
    An uplift of the ocean bottom caused by a submarine earthquake can trigger acoustic-gravity waves that travel at near the speed of sound in water and thus may act as early tsunami precursors. We study the spatiotemporal evolution of the pressure field induced by acoustic-gravity modes during submarine earthquakes, analytically. We show that these modes may all induce comparable temporal variations in pressure at different water depths in regions far from the epicenter, though the pressure field depends on the presence of a leading acoustic-gravity wave mode. Practically, this can assist in the implementation of an early tsunami detection system by identifying the pressure and frequency ranges of measurement equipment and appropriate installation locations.
  • Article
    Three-dimensional global scale underwater sound modeling: The T-phase wave propagation of a southern Mid-Atlantic ridge earthquake
    (Acoustical Society of America, 2019-09-30) Oliveira, Tiago C. A. ; Lin, Ying-Tsong
    A three-dimensional (3D) geodesic Cartesian parabolic equation model is utilized to study the propagation of low-frequency underwater sound (5 to 20 Hz), the so-called T-phase wave, triggered by a Southern Mid-Atlantic Ridge earthquake. The sound from the earthquake was recorded at 1050 km from the epicenter by the deep water hydrophones of the Comprehensive Nuclear-Test-Ban Treaty Organization network near Ascension Island. A few hours later and at 8655 km from the epicenter, the hydrophones of the Shallow Water 2006 experiment in the U.S. East coast also registered the sound. Recorded field data showed discrepancies between expected and measured arrival angles indicating the likely occurrence of horizontal sound reflection in the long waveguide journey. Numerical modeling of this T-phase wave propagation across the Atlantic Ocean with realistic physical oceanographic inputs was performed, and the results showed the importance of 3D effects induced by the Mid-Atlantic Ridge and Atlantic Islands. Future research directions, including localization of T-phase wave generation/excitation locations, are also discussed.