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Surveys of offset linear cultural features that cross the surface ruptures of the 17 August and 12 November 1999 earthquakes on the North Anatolian fault in Turkey yield slip values as large as or larger than those recorded by near-field measurements in the same areas immediately after the earthquake. Using long, linear alignments of trees, fence lines, walls, and canals, we demonstrate as much as a 2-m increase in observed slip over the initial field measurements. On an average, we observed about 15% of the total lateral slip as off-fault deformation, with values ranging from 0% to 40% of the total slip. Part of this lateral deformation is accommodated by bending or drag in a zone as much as 30 m in width, although usually the zone varies between 5 and 20 m in width. This supports the idea that substantial nonbrittle, off-fault deformation is associated with ruptures in areas of alluvial fill. Alternatively, there may …