Abstract: In areal seismic exploration, seismic impulses are generated successively at locations spaced along a centrally located, asymmetic sawtooth shot-point line which regularly crosses a median line coincident with the line of survey. Seismic waves resulting from each impulse are detected at at least a pair of detector spreads each parallel to the median line, but offset from each other a distance equal to an integral multiple of the vertical offset of the shot-point line. Preferably the detected signals are summed on a cross-steered basis, such that the resulting traces associated with crossed sets of centerpoints normal to the survey line provide directional ("dip") information to better indicate areal subsurface structure. Additionally, the dectected signal can be stacked on a common depth point bases (CDPS).