Chapter 29: Integrated Approach for Surface-wave Analysis from Near Surface to Bedrock
Ali Ismet Kanlı, 2010. "Integrated Approach for Surface-wave Analysis from Near Surface to Bedrock", Advances in Near-surface Seismology and Ground-penetrating Radar, Richard D. Miller, John H. Bradford, Klaus Holliger
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A study of surface-wave analysis can be divided into two main parts. In the first stage, dispersive Rayleigh waves are extracted using multichannel analysis of surface waves (MASW) and then are inverted using a genetic-algorithm (GA) method to obtain shear-wave velocity profiles of the investigated site. A new interactive-based inversion algorithm that includes both GA and surface-wave inversion schemes was used in an MASW study. A special type of seismic source (SR-II, or Kangaroo) proved to be very effective in surface-wave studies. The standard-penetration-test data (SPT) and the shear-modulus distribution map derived from MASW data are compared with borehole results aimed for geotechnical applications. In the second stage, a microtremor survey carried out parallel to the MASW survey estimated lateral variations in sedimentary-basin depths up to bedrock. A shear-wave velocity profile of basin sediments is estimated from the GA inversion of the microtremor horizontal-to-vertical (H/V) spectrum based on surface waves from seismic noise at each site. Average shear-wave velocities estimated from the MASW survey are given as constraints in the microtremor inversion process. A new relationship between the resonance frequency f0 and the thickness of the overlaying layer H is derived. A combination of active-and passive-source surface-wave analysis methods is proposed to obtain the optimum shear-wave velocity model from near surface to bedrock.
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Near-surface seismology and ground-penetrating radar (GPR) have enjoyed success and increasing popularity among a wide range of geophysicists, engineers, and hydrologists since their emergence in the latter half of the twentieth century. With the common ground shared by near-surface seismology and GPR, their significant upside potential, and rapid developments in the methods, a book bringing together the most current trends in research and applications of both is fitting and timely. Conceptually, near-surface seismology and GPR are remarkably similar, and they share a range of attributes and compatibilities that provides opportunities to integrate processing and interpretation workflows, which makes them a perfect pair to share pages in a book.
With growth in numbers and professional emphasis have come sections, focus groups, and even professional societies specifically promoting near-surface geophysics. The emergence of near-surface geophysics groups, beginning in the late 1990s and extending into the early twenty-first century, has fueled a diversity of opportunities for professional collaborations. A range of workshops and shared publications has been the fruit of collaborative efforts. The near-surface community continues to extend and develop methods and approaches necessary to satisfy increasing demands in some of the socioeconomically pertinent disciplines such as civil and environmental engineering and hydrology. This book represents the first formal cooperative effort undertaken by the near-surface communities of the Society of Exploration Geophysicists, the American Geophysical Union, and the Environmental and Engineering Geophysical Society.