Shallow Refraction Seismics

Authors


Abstract

This book is a welcome addition to the literature on shallow engineering seismic refraction surveying (“refraction seismics” in the European parlance). The theoretical approach given is general, while the practical applications discussed mainly concern surveys over shallow alluvial basins covering crystalline rocks.

The book is divided into five major subtopics. First, the basic principles of refraction and diffraction are covered in 20 well-written pages. Second, depth formulae are developed for multilayer media in a 22-page chapter, and the concepts of parallelism and reciprocity of traveltime curves are introduced. Third, by far the longest chapter (173 pages) is devoted to interpretation methods. A very lucid and complete treatment is given for the author's preferred method, the ABEM method of interpretation (named for a Swedish company with these initials). The relationship between this method and other more familiar ones (such as delay times, plus-minus, Hales' method, and the wavefront method) is clearly explained. It should be noted, however, that interpretation is limited to the analysis of first arrivals, and amplitudes are not considered. Fourth, instrumentation, field work and interpretation procedures are covered in 18 pages. The author wisely avoids a lengthy chapter of general advice, since each investigator generally will be using different equipment to solve a unique field problem. Fifth, a pleasant bonus is the 79-page chapter on applications of refraction seismics to a variety of situations. These brief case histories involve 200-m-long profiles with interpretation to a depth of 20–40 km. Almost all of the examples are taken from Norway and Sweden.