Chapter 3B Seismic techniques

Publisher Summary This chapter deals with the capabilities and limitations of seismic methods and seismic data in studies of continental rifts. Substantial structural and velocity variations are expected, and are commonly observed, in continental rifts because of the effects of extension, magmatism, and high heat flow associated with the rifting process. The chapter describes the seismic methods that have been used in rift studies, followed by a review of seismic properties of rocks emphasizing effects of temperature. The extensive crustal velocity data available for North America, which identifies the characteristic crustal properties associated with continental rifts, are also utilized. Each method has its own capabilities and limitations in terms of the depth range of investigation, degree of resolution attainable, and the physical properties determined. At present, shear-wave velocity, anisotropy, and Poisson's ratio data from continental rift areas are relatively sparse. Similarities between the crustal velocity structures observed in North America and east Africa suggest the common characteristics of the stable continental crust, and the processes and effects of continental rifting.