FIG. A-20. Arrays used for geophone or source arrays. The array elements are shown by the open circles, triangles and numbers indicate the effective element locations and weightings in different directions; the inline direction is horizontal in each instance. (a) Inline; (b) perpendicular; (c) cross; (d) 3×3 diamond; (e) X-array; (f) rectangular array; (g) crow’s-foot array; (h) odd-arm star; (i) herring-bone array; (j) and windmill array.