Simulation of SH- and P-SV wave propagation in fault zones

eismic fault-zone (FZ) trapped waves provide a potentially high-resolution means for investigating FZ and earthquake properties. Seismic waves emitted within and travelling along low-velocity FZ layers may propagate many kilometres within the low-velocity structure associated with the fault. Waveform observation of FZ trapped waves can be modelled in terms of FZ layer velocities, thicknesses and attenuation coefficients. This can greatly improve the resolution of imaged FZ structure and microearthquake locations. At present, broad-band theoretical seismograms are restricted to plane-parallel layers of uniform properties, However, it is not clear how realistic these models are compared with actual fault structures which could, for example, flare outwards near the surface, have irregular boundaries, interior heterogeneities, etc. To address these interpretational uncertainties, we perform finite-difference simulations for irregular FZ geometries and non-uniform material properties within the layers. The accuracy of the numerical solutions are verified by comparison with the analytical solution of Ben-Zion & Aki (1990) for plane-parallel structures. Our main findings are: (1) FZs can widen at the crustal surface only slightly modifying the trapped waves; (2) velocity variations with depth destroy trapped wave propagation at all wavelengths; (3) FZ trapped waves can be obscured by the presence of a low-velocity surface layer; (4) models with short-scale random structures suggest that trapped waves average out irregular FZ geometries, and hence can be effectively modelled by average-property plane-layered media for the observed range of wavelengths.

@article{id334,
  author = {Igel, H. and Ben-Zion, Y. and Leary, P. C.},
  journal = {Geophys. J. Int.},
  language = {en},
  number = {3},
  pages = {533-546},
  title = {Simulation of SH- and P-SV wave propagation in fault zones},
  volume = {128},
  year = {1997},
}

%O Journal Article
%A Igel, H.
%A Ben-Zion, Y.
%A Leary, P. C.
%J Geophys. J. Int.
%G en
%N 3
%P 533-546
%T Simulation of SH- and P-SV wave propagation in fault zones
%V 128
%D 1997