Difference between revisions of "Dictionary:Array (seismic)"
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[[File:Sega20.jpg|thumb|600px|FIG. A-20. <b>Arrays</b> 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. (<b>a</b>) Inline; (<b>b</b>) perpendicular; (<b>c</b>) cross; (<b>d</b>) 3×3 diamond; (<b>e</b>) X-array; (<b>f</b>) rectangular array; (<b>g</b>) crow’s-foot array; (<b>h</b>) odd-arm star; (<b>i</b>) herring-bone array; (<b>j</b>) and windmill array.]]
Latest revision as of 18:19, 6 June 2020
1. A group of geophones or other seismic receivers connected to a single recording channel (geophone array) or a group of sources to be activated simultaneously (source array). The records from nearby sources when vertically stacked also effectively constitute a source array. Sometimes called a pattern (especially for a source array) or a patch (especially when the array is large).
2. The arrangement or pattern of a group of geophones or sources (Figure A-20). Arrays discriminate against events on the basis of their moveout or apparent wavelength; see directivity graph. For a uniform array (see Figure D-15) of n geophones separated by the distance d, the effective array length is nd and the first null response occurs when the apparent wavelength equals this. The half-width of the main lobe at 0.7 peak amplitude defines the pass wavelength. For a nonuniform array, the effective array length is the length of the uniform array that has the same pass wavelength. Compare spread.