Seismic technology has been an integral part of hydrocarbon exploration since the first seismic exploration patent in 1917 and the first field test in Oklahoma in 1921. Borehole acoustics was first patented in 1935 and successfully developed later as a continuous velocity logging tool, providing a much finer vertical subsurface perspective than seismic acoustics. Rock physics is the crucial discipline that interfaces acoustic wave amplitude and velocities, from seismic or borehole sonic measurements, with petrophysical characterization. The foundation for theoretical rock physics can be traced back to seminal works between the 1940s and the 1960s by Maurice A. Biot and Fritz Gassmann.

This is the third edition of our book Fundamentals of Ocean Acoustics, revised and supplemented, including much new material responding to the progress in the theory of sound propagation and scattering in the ocean over the last 10 years. New topics are devoted mainly to such questions as the intrathermoclinc lenses and their effect on sound fields in the ocean, weakly divergent bundles of rays, ocean acoustic tomography, coupled modes, invariants of an interference pattern in a range-dependent oceanic waveguide, sound scattering by random highly anisotropic volume inhomogeneities (fluctuations of the refractive index of the sea medium) with a fractal spectrum, fractal nature of low-frequency attenuation in the underwater sound channel, small-slope approximation in treating sound scattering from the rough sea surface (Voronovich's approach), sound scattering by an air bubble near the sea surface, collective bubble behaviour, etc. Both the direct and inverse problems arc considered. Some rccent experimental data arc also added. More than 60 new references are presented. Some new references and figures arc preceded by the letter A.The book is intended for experts in acoustics and oceanology, engineers, postgraduates, and students of universities and institutes of geophysical and hydrometeorological profiles. Thus, it can be used as a scientific monograph and textbook of advanced type. The authors arc grateful to T.l. Tsyplakova for her great help in preparing the manuscript.