Mathematical Foundation of Elastic Wave Propagation
Seismic body waves – whether compressional or shear – are subjected to reflection and refraction at layer boundaries with impedance contrast and diffraction at a sharp discontinuity. Based on the elastic wave theory described in Appendix A, we now review the nature of P- and S-wave propagation. To a great extent, seismic waves traveling in the earth can be considered as elastic waves. Therefore, we can use the wave equation (A-30) for elastic solids to describe seismic wave propagation. As P- and S-waves travel within an elastic solid, they are called body waves. Source types used in seismic surveys often generate P-waves. Nevertheless, at non-normal incidence, part of the P-wave energy is converted to S-waves. The P-to-S conversion phenomenon is the basis for the multicomponent seismic method.
Figures & Tables
The narrow scope of engineering seismology includes its application to geotechnical site investigations for buildings and engineering infrastructures, such as dams, levees, bridges, and tunnels, and landslide and active-fault investigations. It also includes seismic microzonation to determine soil amplification and liquefaction susceptibility within a municipal area to estimate the earthquake risk. The broad scope of engineering seismology also includes its application to groundwater exploration, coal and mineral exploration, geothermal exploration, and investigations of historic buildings and archaeological sites. This book primarily is devoted to application of the seismic method to geotechnical engineering. Nevertheless, the book also includes chapters on case studies for the broader scope of engineering seismology.