Determination of the 30-year creep trend on the Ismetpaşa segment of the North Anatolian Fault using an old geodetic network

Abstract

The Ismetpaşa segment of the North Anatolian Fault was ruptured during both the 1944 (Mw = 7.2) Gerede and 1951 (Mw = 6.9) Kurşunlu earthquakes. The field studies carried out in the aftermath of these two major earthquakes showed that the Ismetpaşa segment had experienced a creep movement. To monitor the surface creep, a geodetic network with six control points was established on the segment. This network was observed three times-in 1972, 1982 and 1992. Based on our evaluations of those observations, the creep on the segment was geodetically determined to be 1.02 cm/year (1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982) and 0.93 cm/year (1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992) respectively. In 1999, the North Anatolian Fault experienced two major shocks-the Mw = 7.4 Gölcük and Mw = 7.2 Düzce earthquakes-both on the western part of the Ismetpaşa fault. Using the global positioning system, our surveying team observed the network one more time in 2002 to assess whether these earthquakes affected the creep of the Ismetpaşa segment, or not. The evaluation of the observations revealed a creep of 0.78 cm/year for the period 1992-2002. This result reveals that the creep of the segment has decreased in a linear fashion between 1972 and 2002 and that it had not been triggered by the Gölcük and Düzce earthquakes.

Triggered creep rate on the Ismetpasa segment of the North Anatolian Fault

“…Therefore, the geodetic network established on the Ismetpasa segment was observed one more time in 2002. Based on this observation campaign, the creep rate of the segment between 1992-2002 was obtained 0.7 cm/year (Kutoglu and Akcin, 2006). This result was also confirmed by the study of Cakir et al (2005), using InSAR technique.…”

“…This first result was compatible with 2.2 cm/year slip rate of the NAF (McClusky et al, 2000). After the discovery of its creep behavior, the Ismetpasa segment had been the center Correspondence to: H. S. Kutoglu (kutogluh@hotmail.com) of interest; many studies using different surveying techniques were carried out to determine its creep rate in different periods (Ambraseys, 1970;Aytun, 1982;Altay and Sav, 1991;Cakir et al, 2005;Kutoglu and Akcin, 2006). A list of these studies and the creep rates obtained are shown in Fig.…”

“…Both studies showed that the creep trend of the segment had not been triggered by Golcuk (M w =7.4) and Duzce (M w =7.2) earthquakes. Whereupon, three different scenarios were delivered for the creep behavior of the segment: (1) if the fault creep started after the 1944 or 1951 earthquakes it might be transient (scenario 1) in time, (2) if the creep on the fault was already present and increased due to any of these earthquakes it might be now decreasing down to its pre-earthquake rate (scenario 2), and (3) as stated by Sylvester (1986) the long term rate of creep may vary before or after earthquakes along the creeping fault segment (scenario 3) (Kutoglu and Akcin, 2006). To understand which scenario would be valid, the Ismetpasa geodetic network was resurveyed in 2007 using GPS technique.…”

“…This paper analyzes the results of this campaign. wall offset- Ambraseys (1970) triangulation- Aytun (1982) creepmeter- Altay and Sav (1991) InSAR- Cakir et al (2005) trilateration- Deniz et al (1993) and Kutoglu and Akcin (2006) linear model for trilateration Deniz et al, 1993). The inset map shows the Ismetpasa geodetic network.…”

Recent tectonic features of the central part (Bolu-Corum) of the North Anatolian Fault

“…After Ambraseys, the first geodetic study was started by establishing triangulation and trilateration network across the fault near Ismetpasa. The geodetic measurements indicate that the rate of creep is 9.3±0.7 mm/yr [10] and 7.8±0.5 mm/yr [11]. Using InSAR technique, Cakir et al, [8] estimated the rate 8±3 mm/yr for the creeping on the section.…”