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Is It Time To Re-Engineer Near-Surface Seismic Refraction Methods?

Summary Most current near-surface seismic refraction operations are under-capitalized, they employ inefficient field procedures, and they deliver an outdated low resolution 2D product. In order to generate growth and more widespread use for environmental and geotechnical applications, it will be necessary to modernize the great majority of refraction operations. The most significant step will be the adoption of 3D methods, which emphasize the superior lateral resolution of geophysical methods, and which generate more detailed geotechnical models of the subsurface. Furthermore, greater use of amplitudes, the other 50% of the data, is recommended to resolve many ambiguities with model-based inversion, to generate density models, and to recognize inhomogeneities such as voids. Implementing these advances will require more efficient approaches to data processing with full trace methods, such as the RCS, if the greatly increased volumes of 3D data and out-of-plane events are to be handled efficiently. Also, more efficient methods of data acquisition using roll-through methods with greatly increased channel counts are necessary for both 2D and 3D methods. These advances will require many geotechnical organizations to decide whether their core business is data acquisition and processing or alternatively, the provision of specialist geotechnical services through the interpretation and integration of results. Most of the technology required to modernize refraction methods already exists. Its adoption is being hindered by an “engineering culture” which emphasizes risk minimization, the strict adherence to standard procedures, the adoption of codes of practice and the use of “proven” products, all of which encourage minimum standards rather than innovation and excellence.