Lecoulant Jean, Oliveira Tiago C A, Lin Ying-Tsong
IRENav, École Navale, Brest, 29200, France.
Physics Department, University of Aveiro, Aveiro, 3810-193, Portugal.
J Acoust Soc Am. 2021 Nov;150(5):3807. doi: 10.1121/10.0007072.
A three-dimensional (3D) hybrid modeling method is used to study the generation and propagation of T waves in the ocean triggered by a Southern Mid-Atlantic Ridge earthquake. First, a finite-element method model named SPECFEM3D is used to propagate seismic waves in the crust and acoustic waves in the ocean for the T-wave generation in a 200 × 50 km area near the epicenter. A 3D parabolic equation (PE) method is then used to propagate the T waves in the ocean for about 850 km further to the hydrophone stations deployed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) near Ascension Island. All of the simulations considered the realistic bathymetry and water sound speed profile. The SPECFEM3D results suggest that T waves with clear modal features could be generated by the concentration of reflected head waves in two depressions 40 km away from the epicenter. To compare with the hybrid modeling method for calculating T-wave propagation losses and arrival azimuths at the CTBTO hydrophones, point source simulations using the 3D PE model from the T waves source locations, identified with SPECFEM3D, were also implemented. The advantages and limitations of each approach are discussed.
一种三维（3D）混合建模方法被用于研究由南大西洋中脊地震引发的海洋中T波的产生和传播。首先，一个名为SPECFEM3D的有限元方法模型被用于在震中附近200×50千米区域内传播地壳中的地震波和海洋中的声波以产生T波。然后，一种三维抛物方程（PE）方法被用于在海洋中进一步传播T波约850千米至全面禁止核试验条约组织（CTBTO）在阿森松岛附近部署的水听器站。所有模拟都考虑了实际的海底地形和水的声速剖面。SPECFEM3D的结果表明，在距离震中40千米的两个凹陷处，反射首波的集中可以产生具有清晰模态特征的T波。为了与混合建模方法计算CTBTO水听器处T波传播损失和到达方位进行比较，还实施了从用SPECFEM3D确定的T波源位置使用三维PE模型的点源模拟。讨论了每种方法的优缺点。
