Park Seismic LLC, Shelton, Connecticut, Tel: 347-860-1223, Fax: 203-513-2056, Email:
Multiple 2-D Vs Profiling  

In practice, however, an approach of multiple (for example, four) 2-D profiling in different directions at different places within the same site has been usually taken to maximize
the thoroughness of the characterization for a given deployment of field equipment and crews (
Fig. 1).  This approach makes it possible to evaluate the stiffness information in
a regional, as well as local, scale.  A pseudo 3-D map of bedrock topography is constructed at this stage, based on the arbitrary high value of Vs immediately following the top
soil layer mapped (
Fig. 2).  In addition, this approach enables detection of shallow voids and cavities (for example, 10 m or less)—the most dangerous potential hazards—
through a special processing approach called side scattering analysis (SSA) described below.  Recently, a 3-D processing has been applied to generate a cubic grid Vs data
set by using multiple sets of 2-D Vs data.  More details are explained below.
Fig. 1.  Field layout map for a typical multiple 2-D Vs surveys
and results of four (4) 2-D Vs maps.
Fig. 2.