Abstract: A fault observed starting from the south of the Tutak town to the Santas village to the northwestextending in N65°W direction for 80-85 km has been detected and named as the Karayazı Fault- Some field evidencessuch as the juxtaposition of the older and younger rock units, the topographic expression, the drainage patternofwaters, aligned springs and the ruins of an ancient settlement observed along the fault zone have been attributedto the fact that the Karayazı Fault may be active.