ABSTRACT Seismoelectric coupling in an electric isotropic and elastic anisotropic medium is developed using a primary–secondary formulation. The anisotropy is of vertical transverse isotropic type and concerns only the poroelastic parameters. Based on our finite difference time domain algorithm, we solve the seismoelectric response to an explosive source. The seismic wavefields are computed as the primary field. The electric field is then obtained as a secondary field by solving the Poisson equation for the electric potential. To test our numerical algorithm, we compared our seismoelectric numerical results with analytical results obtained from Pride's equation. The comparison shows that the numerical solution gives a good approximation to the analytical solution. We then simulate the seismoelectric wavefields in different models. Simulated results show that four types of seismic waves are generated in anisotropic poroelastic medium. These are the fast and slow longitudinal waves and two separable transverse waves. All of these seismic waves generate coseismic electric fields in a homogenous anisotropic poroelastic medium. The tortuosity has an effect on the propagation of the slow longitudinal wave. The snapshot of the slow longitudinal wave has an oval shape when the tortuosity is anisotropic, whereas it has a circular shape when the tortuosity is isotropic. In terms of the Thomsen parameters, the radiation anisotropy of the fast longitudinal wave is more sensitive to the value of e, while the radiation anisotropy of the transverse wave is more sensitive to the value of δ.

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二维 VTI 多孔弹性介质中的震电数值模拟

摘要 电各向同性和弹性各向异性介质中的地震电耦合是使用一次-二次公式开发的。各向异性是垂直横向各向同性类型，仅涉及多孔弹性参数。基于我们的有限差分时域算法，我们解决了对爆炸源的地震电响应。地震波场被计算为主场。然后通过求解电位的泊松方程获得电场作为二次场。为了测试我们的数值算法，我们将我们的震电数值结果与从 Pride 方程获得的分析结果进行了比较。比较表明，数值解对解析解给出了很好的近似。然后我们模拟不同模型中的地震电波场。模拟结果表明，在各向异性多孔弹性介质中产生了四种类型的地震波。这些是快速和慢速纵波和两个可分离的横波。所有这些地震波都会在均匀的各向异性多孔弹性介质中产生同震电场。曲折度对慢纵波的传播有影响。当曲折度为各向异性时，慢纵波的快照为椭圆形，而当曲折度为各向同性时，其快照为圆形。在汤姆森参数方面，快纵波的辐射各向异性对 e 的值更敏感，而横波的辐射各向异性对 δ 的值更敏感。这些是快速和慢速纵波和两个可分离的横波。所有这些地震波都会在均匀的各向异性多孔弹性介质中产生同震电场。曲折度对慢纵波的传播有影响。当曲折度为各向异性时，慢纵波的快照为椭圆形，而当曲折度为各向同性时，其快照为圆形。在汤姆森参数方面，快纵波的辐射各向异性对 e 的值更敏感，而横波的辐射各向异性对 δ 的值更敏感。这些是快速和慢速纵波和两个可分离的横波。所有这些地震波都会在均匀的各向异性多孔弹性介质中产生同震电场。曲折度对慢纵波的传播有影响。当曲折度为各向异性时，慢纵波的快照为椭圆形，而当曲折度为各向同性时，其快照为圆形。在汤姆森参数方面，快纵波的辐射各向异性对 e 的值更敏感，而横波的辐射各向异性对 δ 的值更敏感。曲折度对慢纵波的传播有影响。当曲折度为各向异性时，慢纵波的快照为椭圆形，而当曲折度为各向同性时，其快照为圆形。在汤姆森参数方面，快纵波的辐射各向异性对 e 的值更敏感，而横波的辐射各向异性对 δ 的值更敏感。曲折度对慢纵波的传播有影响。当曲折度为各向异性时，慢纵波的快照为椭圆形，而当曲折度为各向同性时，其快照为圆形。在汤姆森参数方面，快纵波的辐射各向异性对 e 的值更敏感，而横波的辐射各向异性对 δ 的值更敏感。