ABSTRACT: Two kinds of methods of alpha track, measurement were carried, out for earthquake and active faults along `the North Anatolian Fault One of them is the short term, other is the continuous measurement method for evaluating the faulty activity.The results by the short, term, method show that, .alpha, track, measurement, is useful to detect even in. the regions repioducibilitiy of the alpha track, measurement if measured, in. nearly the same- temperature condition.The results by the continuous measurement, method show mainly. In both two methods, however, the undergrond water supply must be taken into consideration before evalution.In. Mekece region, east of Iznik, the seismic gap area of one branch of the North Analolioo Fault Zone» the maximum .alpha track, density obtained, by both methods is abnormally high,.. Furthermore, the result, by the long term measuring method shows, the highest value in winter,., These facts indicate that this, branch of the- North Anatolian. Faults, is. very active