J. Geodynamics Vol. 26, No. 2-4, pp. 197-216, 1998 Pergamon 0 1998 Published by Elsevier Science Ltd All rights reserved. Printed in Great Britain zyxwvuts PII: SO264-3707(97)00052-5 026&3707/98 519.OOt 0.00 zyxwvutsr FRACTAL ANALYSIS OF NORMAL FAULTS IN NORTHWESTERN AEGEAN AREA, GREECE THEODOR DOUTSOS* and IOANNIS KOUKOUVELAS Department of Geology, University of Patras, 26101 Patras, Greece (Received 18 November 1996; revised 3 June 1997; accepted 13 August 1997) Abstract-Normal faults within the Ptolemais coal field and large seismogenic faults in the northwestern Aegean remain fractal for displacement values larger than about 1 m. The kinematic parameters on reverse drag profiles such as length of rollover, footwall uplift and wavelength of footwall uplift show that all three parameters have a power law relationship, expressed by a c exponent of about 1, with the maximum displacement which take place across the fault. Footwall uplift/hanging wall subsidence ratio is about l/2. The displacement analysis help us to propose a growth model for larger seismogenic faults in the NW Aegean, as is the ‘Hepiros fault set’ and the ‘Aliakmon fault zone’. Faults within the ‘Aliakmon fault zone’ were independently developed, at the first stages of deformation, by tip line deformation and out-of plane bifurcation, whereas later, defor- mation continued by segment linkage. One of these faults the ‘Sarakina fault’ was react- ivated during the 1995 earthquake to produce a 25 km long surface rupture. A long term slip rate of about 0.3 mm a-’ has been estimated by taking into consideration that over the past 6 Ma a maximum displacement of 1700 m across this fault has taken place. 0 1998 Published by Elsevier Science Ltd. All rights reserved INTRODUCTION The displacement field of a blind normal fault has been described to have an elliptical shape with the fault surface as a principal plane (Rippon, 1985). Fault surface ellipses have an horizontal major axis termed as the ‘fault width’ (1) and a short axis ‘down-dip fault height’ (h) (Fig. 1) (Walsh and Watterson, 1989). The maximum displacement (&ax) occurs at the central part of the fault surface and diminishes toward their edges (Fig. 1). In addition displacement decreases to zero along a normal to the fault surface to form the characteristic flexural profile of several normal faults (Gibson et al., 1989). The variation in displacement along this direction is expressed by a longer hanging wall rollover (r,) and a shorter wavelength of footwall uplift (r- J. The relationships between these geometric and kinematic parameters have been recog- *Author to whom all correspondence should be addressed: E-mail: tdoutsos@upatras.gr; Fax: (61) 994485. 197