Simulation of seismic waves at the earth's crust (brittle–ductile transition) based on the Burgers model

摘要: Abstract. The earth's crust presents two dissimilar rheological behaviors depending on the in situ stress-temperature conditions. upper, cooler part is brittle, while deeper zones are ductile. Seismic waves may reveal presence of transition but a proper characterization required. We first obtain stress–strain relation, including effects shear seismic attenuation and ductility due to deformations plastic flow. anelastic behavior based Burgers mechanical model describe steady-state creep Lame constant brittle ductile media depends stress temperature through viscosity, which obtained by Arrhenius equation octahedral criterion. P S wave velocities decrease as depth increase geothermal gradient, an effect more pronounced for waves. then P−S SH equations motion recast velocity-stress formulation, memory variables avoid computation time convolutions. correspond isotropic inhomogeneous solved direct grid method Runge–Kutta stepping technique Fourier pseudospectral method. algorithm tested with success against known analytical solutions different viscosities. A realistic example illustrates surface reverse-VSP synthetic seismograms abrupt brittle–ductile transition.