A METHOD IS DISCLOSED FOR AMPLITUDE PRESERVING KIRCHHOFF TIME MIGRATION. THE METHOD INCLUDES CALCULATING (12) ESTIMATES OF THE GEOMETRICAL SPREADING TERMS USING A CONSTANT VELOCITY APPROXIMATION. TAKEOFF AND EMERGENCE ANGLES ARE ACCURATELY CALCULATED (14) BASED ON A MODEL OF VELOCITY WHICH VARIES WITH RESPECT TO TRAVEL TIME. AN IMAGE CAN BE CALCULATED AT LEAST ONE TRAVEL TIME USING THE ESTIMATED WEIGHTS AND CALCULATED TAKEOFF AND EMERGENCE ANGLES. FIGURE 1
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