Internal co-seismic displacement and strain changes inside a homogeneous spherical Earth

Abstract

Summary In this study, we devised a new set of analytical foundation solutions to compute the internal co-seismic displacement and strain changes caused by four independent point sources (strike-slip, dip-slip, horizontal tensile, and vertical tensile) inside a homogeneous spherical Earth model. Our model provides constraints on the deformation properties at depth, and reveals that the internal co-seismic deformation is larger than that on the surface. The deformation near the source is convergent with our formulae. For the internal deformation at radial section plane, the patterns of horizontal displacements ${u_\theta },{u_\phi }$ and strain changes ${e_{rr}},{e_{\theta \theta }},{e_{\phi \phi }},{e_{\theta \phi }}$ caused by strike-slip and tensile sources appear symmetric at the equidistance above and below the source. Their amplitudes are not identical but with a small discrepancy actually. Unlike these, the patterns of radial displacements ${u_r}$ for strike-slip and tensile sources exhibit point symmetry with the equidistance from the source. Also, the corresponding amplitudes are slightly different. The displacements ${u_\theta },{u_\phi }$ and strain changes ${e_{rr}},{e_{\theta \theta }},{e_{\phi \phi }},{e_{\theta \phi }}$ caused by dip-slip also appear the same properties as ${u_r}$ of strike-slip source. The magnitudes of the displacements and strain changes depend on the source types. The curvature effect on the near-field surface deformations is small, and it increases with the studied depth. But for the far-field deformation caused by the strike-slip source (ds = 20 km), the curvature effect can be as large as 77 per cent when the epicentral distance approximates to 1778 km.

Coupling fraction model to interpret the motion of non-fully coupled strike-slip faults

“…Dislocation theory, which interprets fault-motion-based deformation on the surface, has become an important physical model since the elastic rebound theory was put forward (Reid 1910;Chinnery, 1963;Okada 1985Okada , 1992Matsu'ura et al, 1986;Okubo, 1993, 1998;Wang et al, 2003;Steketee, 1958;Pan, 2019;Dong et al, 2021). The simplest representation of dislocation along an infinitely deep and long strike-slip fault is shown in Figure 1A.…”

Coseismic Gravity Gradient Changes in a Spherical Symmetric Earth Model: Application to the 2011 Tohoku‐Oki Earthquake

“…Dong, Cheng, et al. (2021) investigated the effect on calculating coseismic deformations based on a discontinuous medium Earth model.…”

“…Zhou et al (2019aZhou et al ( , 2019bZhou et al ( , 2020aZhou et al ( , 2020b and Dong, Cambiotti, et al (2021) systematically discussed the internal deformation, Green's functions, and Love numbers excited by a point dislocation. Dong, Cheng, et al (2021) investigated the effect on calculating coseismic deformations based on a discontinuous medium Earth model.…”