Reflection and transmission of thermoelastic waves in multilayered media

Abstract

In many cases, multilayered media with flat interfaces are a suitable representation of the geologic features of the crust. In general, the isothermal theory is used, and the transfer-matrix (TM) method is applied to compute the scattering reflection and transmission (R/T) coefficients. We have generalized the TM algorithm to the more general case of thermoelastic layers, in which elastic waves give rise to a temperature field (the thermal [T] wave) and vice versa. The stress-strain relation is based on the Lord-Shulman (LS) thermoelasticity theory. Then, the R/T coefficients of the fast compressional (P), T, and shear (S) waves are computed and verified by the conservation of energy. We also obtain the energy ratios and phase angles for P- and S-wave incidences. We consider a hot dry rock (HDR) geothermal model to study the effects of temperature, frequency, and layer thickness, and we find that the coefficients potentially can be used to obtain information about the characteristics of a multilayered medium.