The Characteristics of Seismic Rotations in VTI Medium

Abstract

Under the assumptions of linear elasticity and small deformation in traditional elastodynamics, the anisotropy of the medium has a significant effect on rotations observed during earthquakes. Based on the basic theory of the first-order velocity-stress elastic wave equation, this paper simulates the seismic wave propagation of the translational and rotational motions in two-dimensional isotropic and VTI (transverse isotropic media with a vertical axis of symmetry) media under different source mechanisms with the staggered-grid finite-difference method with respect to nine different seismological models. Through comparing the similarities and differences between the translational and rotational components of the wave fields, this paper focuses on the influence of anisotropic parameters on the amplitude and phase characteristics of the rotations. We verify that the energy of S waves in the rotational components is significantly stronger than that of P waves, and the response of rotations to the anisotropic parameters is more sensitive. There is more abundant information in the high-frequency band of the rotational components. With the increase of Thomsen anisotropic parameters ε and δ, the energy of the rotations increases gradually, which means that the rotational component observation may be helpful to the study of anisotropic parameters.

Six‐Component Earthquake Synchronous Observations Across Taiwan Strait: Phase Velocity and Source Location

“…Keil et al (2021) use a 6C station installed in Munich to study the microzonation and inverse the 1D velocity profiles, where the urban area is complex and not suitable for installation of seismometer array. In addition, rotational motions play important roles in the inversion of source parameters and anisotropic parameters, wavefield separation and reconstruction, earth's toroidal free oscillations, volcano seismology, tilt correction (Bernauer et al, 2014(Bernauer et al, , 2020Igel et al, 2011;Lin et al, 2022;Lindner et al, 2017;Sollberger et al, 2016Sollberger et al, , 2020Sun, Wang, Li, & Wei, 2021).…”