f Implementing pre-stack rotation for four-component shear-wave reflection data

Source-geophone rotation has now become a conventional procedure for processing four-component (two-horizontal sources and two-horizontal receivers) shear-wave reflection data, as demonstrated by Alford (1986), and Squires et al. (1989) and among others. To apply source-geophone rotation, a post-stack rotation analysis (Alford 1986; Squires et al. 1989), or a least square fitting procedure (Murtha 1989) is required to determine the optimum rotation angle. Since it is computing intensive and time consuming, pre-stack rotation is an unwelcome additional procedure (Sriram et al. 1990).