ORI GIN AL PA PER

Can a creeping segment become a monitorbefore destructive major earthquakes?

H. S. Kutoglu • K. S. Gormus • T. Deguchi • E. Koksal •

H. Kemaldere • O. Gundogdu

Received: 3 October 2011 / Accepted: 18 October 2012 / Published online: 30 October 2012� Springer Science+Business Media Dordrecht 2012

Abstract There are few places in the world to monitor aseismic creep. One of them is the

Ismetpasa segment of the North Anatolian Fault. The observations in the Ismetpasa showed

that the creep rate progressively decreased along the 40 years before the 1999 Kocaeli-

Golcuk (Mw = 7.6) earthquake and then started increasing. This phenomenon might be a

systematic of the creeping segments. If it is the case, this behavior can be utilized for early

warning before the expected major earthquake in the Marmara Sea. In this study, the creep

rate of the segment has been studied by GPS and InSAR technologies. The results showed

that the rate has decreased to 1.3 cm a year. This result might be an indication of stress

starting increase. If the segment retains the decreasing trend and it is ceased by a major

earthquake, it would be a proof of the relationship between the creep process and the

earthquakes. Then, the creep process might be utilized for early warning.

Keywords Surface creep � Geodetic survey � North Anatolian Fault �Earthquake prediction

1 Introduction

Earthquake prediction is a challenging topic in the earth science. It is well known that some

surface deformations before the earthquakes happen around the fault lines (Press 1975).

The authors dedicate this paper to the memory of Prof. Dr. Aykut Barka who was the pioneer earth scientistin Turkey contributing to understanding behavior of the North Anatolian Fault Zone.

H. S. Kutoglu (&) � K. S. Gormus � E. Koksal � H. KemaldereHazard Monitoring and Research Laboratory, Department of Geodesy and Photogrammetry,Zonguldak Karaelmas University, 67100 Zonguldak, Turkeye-mail: kutogluh@hotmail.com

T. DeguchiNitetsu Mining Company, Tokyo, Japan

O. GundogduDepartment of Geophysics Engineering, Istanbul University, Istanbul, Turkey

123

Nat Hazards (2013) 65:2161–2173DOI 10.1007/s11069-012-0466-0

Nowadays, Geodetic monitoring techniques such as Global Positioning System (GPS) and

Interferometric Synthetic Aperture Radar (InSAR) are the most useful tools for monitoring

these deformations. They can therefore be used for early warning before major earth-

quakes. Here, the main problem is to guess where the earthquake would occur and to

observe the right location in the right time. In this respect, the North Anatolian Fault (NAF)

might be the most proper fault system in the world because it has a progressive failure

systematic migrating westward since 1939 (Barka 1996; Stein et al. 1997).

Strike slip faults are the most important type of active faults because of the destructive

major earthquakes that they have produced. The major strike slip faults may be thousand of

kilometers long and tens of kilometers wide (Sylvester 1988). And the NAF is the most

spectacular strike slip fault in the world. The importance of the NAF comes from

the destructive major earthquakes (Table 1) which is experienced in the last century

(Barka 1992).

The NAF is a right lateral strike slip fault which runs through the border of Iran to the

Marmara Sea along a length of about 1,200 km (Sengor et al. 1985; Barka 1992; Saroglu

and Kuscu 1992). The first studies on the NAF were provoked after the four earthquakes

ruptured 725 km of the NAF during 1939–1944 (Stein et al. 1997). After that, many studies

were carried out to determine the fault features and mechanism (Ketin 1969; Sengor et al.

1985; Allen 1969; Dewey 1976; Ambraseys 1970; Barka 1992; Saroglu and Kuscu 1992).

With the advent of Global Positioning System (GPS), the yearly slip rate of the fault was

determined averagely 2.2 cm in 1990s (Stein et al. 1997; McClusky et al. 2000; Reilinger

et al. 2000). By the way, the NAF was ruptured eight times more by the earthquakes

(Mw [ 6.7) until 2000. The most important finding in relation to these earthquakes is that

they have a progressive failure systematic migrating westward (Fig. 1) (Stein et al. 1997).

In this respect, a next major earthquake is expected on its branches in the Marmara Sea

(Parsons et al. 2000; Parsons 2004).

The strike slip faults are mostly locked on the surface between large stress-releasing

events, but can creep in some cases (Malservisi et al. 2003; Bilham et al. 2004). There are

two major strike slip fault systems in which surface creep has been documented; these are

the NAF and the San Andreas Fault in California (Ambraseys 1970; Aytun 1982; Sylvester

1988; Lienkaemper et al. 1991; Galehouse 1992). Although the occurrence of creep is

documented, the interactions between locked and creeping portions of a fault and the

conditions that lead to creep are not well understood (Malservisi et al. 2003; Kanu and

Johnson 2011).

Table 1 Major earthquakesexperienced on the NAF since1939

Earthquake center Occurrence date Magnitude Death

Erzincan 26 12.1939 7.9 32,962

Erbaa-Niksar 20.12.1942 7.3 534

Kastamonu-Samsun 27.11.1943 7.6 2,824

Bolu-Gerede 01.02.1944 7.4 3,959

Varto-Ustukran 31.05.1946 7.8 839

Yenice-Gonen 18.03.1953 7.5 265

Abant 26.05.1957 7.0 52

Varto 19.08.1966 7.0 2,394

Adapazarı-Mudurnu 22.07.1967 7.1 89

Kocaeli-Golcuk 17.08.1999 7.6 17,127

Duzce-Kaynaslı 12.11.1999 7.2 845

2162 Nat Hazards (2013) 65:2161–2173

123

The creeping segment of the NAF is called ‘‘Ismetpasa segment’’ (Fig. 2). The creep

behavior on this segment was realized through the offsets on the wall of the Ismetpasa train

station (Fig. 3). The rate of the creep was first measured between 1957 and 1969 on this

wall (Ambraseys 1970; Aytun 1982). Then, the measurements were carried out by different

surveying techniques, for example, creepmeter, Electronic Distance Meter (EDM),

Doppler technique (Ugur 1974; Eren 1984; Altay and Sav 1991; Deniz et al. 1993). These

measurements showed that the creep rate was systematically decreased before the 1999

event. After this event, the observations were maintained by the modern geodetic tech-

nologies such as GPS and InSAR to monitor temporal changes in the creep rate (Cakir

et al. 2005; Kutoglu and Akcin 2006; Kutoglu et al. 2008). The results surprisingly showed

that the creep rate was accelerated after the 1999 event (Fig. 4).

The finding above makes monitoring the Ismetpasa creep rate more important than ever

because there might be a relationship between ongoing changes in the creep rate and

increasing stress over the NAF system. If so, its temporal change might be used for early

warning before the next major earthquake expected in the Marmara Region (Kutoglu et al.

2010). Therefore, the segment has been periodically observed by GPS and InSAR tech-

niques. In this study, the results obtained from the observations in 2011 are discussed.

2 Monitoring the creep

Monitoring tectonic movements is an ultimate application of the geodetic science. GPS and

InSAR techniques of the geodesy are the most effective tools for this purpose. GPS is the

most powerful technique for pointwise deformation monitoring while InSAR is the most

suitable method for monitoring wide-area deformations. For that reason, both methods are

applied in this study.

2.1 GPS monitoring

Use of GPS for tectonic movements requires obtaining in millimeter precision to detect

small site displacements (Wesley 1989). For precise positioning, many parameters and

Fig. 1 Progressive failure systematic of the NAF (USGS 2010)

Nat Hazards (2013) 65:2161–2173 2163

123

Ismetpasa segment

1999 M7.4 Kocaeli Erth.

1944 M7.4 Gerede Erth.

1951 M6.9 Kursunlu Erth.

Geodetic network

North

Fig. 2 Location of Ismetpasa segment and geodetic network. The solid white lines are the segments of theNAF. The stars locate the major earthquakes that occurred in the last century, and triangles in the lowerright figure mark the location of the micro-geodetic network points (Source of base satellite image: GoogleEarth)

Fig. 3 Creeping wall in the Ismetpasa town

2164 Nat Hazards (2013) 65:2161–2173

123

error sources must be taken into account and eliminated during observations and data

processing. Observations utilized are the L1 and L2 carrier phase observations gathered in

static surveying method (Hofmann-Wellenhof et al. 1997). Session durations are recom-

mended between 8 and 24 h in order to minimize error limits of the observations (Eckl

et al. 2001). During data processing, precise ephemerides of the GPS satellites published

by International GNNS Service (IGS) must be used; ionospheric delay error is eliminated

through ionosphere free phase combination, and tropospheric delay is commonly modeled

by Sastamoinen troposphere model. Orbit interpolations for proper epochs should be

conducted by dynamic models; Earth Orientation Parameters must therefore be introduced

in the process (Gurtner 1993; Kutoglu 2010). In addition, the multi-station solution strategy

instead of the single baseline solution is applied for the network adjustment. For these

purposes, scientific GPS data processing software tools such as GAMIT, BERNESE

GIPSY, etc. are utilized for this sort of the applications (Hofmann-Wellenhof et al. 1997;

Teunissen and Kleusburg 2010; Even-Tzur et al. 2004).

To monitor the creep rate of the Ismetpasa segment, 13 points with pillar have been

utilized (Fig. 5). The six of them which are utilized for the object points are the points of

the local geodetic network in the Ismetpasa town established in 1972. PENC, MATE, and

POL2 are the International Terrestrial Reference Frame (ITRF) points of IGS and chosen

for datum definition of the geodetic networks. The other IGS points SOFI, BUCU, ISTA,

and ANKR have been used for working with shorter baselines and gaining a better dis-

tribution of network points and hence for obtaining better accuracy.

The IGS points are continuously operated by GPS technique and their observations

acquired in the epochs of 30 s can be obtained from the website of the IGS. The object

points beside the fault line were observed in two different GPS campaign in 2008 and 2010

with 19 months interval. The points were occupied 3 days and 8 h in the 2008 campaign.

Cre

ep r

ate

(cm

/yea

r)

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 20100.5

1

1.5

2

2.5

3

Year

Aytun 1982triangulation

Eren 1984Doppler trilateration Deniz 1993

EDM trilateration

Ambraseys 1970wall offset

Cakir et. al. 2005InSAR

Kutoglu and Akcin 2006GPS network

Kutoglu et. al. 2008GPS network

Kutoglu et. al. 2010GPS network

17 August 1999Mw=7.6 Kocaeli Earthquake

Fig. 4 Average creep rates determined at Ismetpasa. The blue vertical lines at data points are error bars

Nat Hazards (2013) 65:2161–2173 2165

123

According to Eckl et al. (2001) and Psimoulis et al. (2004), this duration is quite good for

reducing errors at sufficient rates for monitoring tectonic movements on the network. In the

2010 GPS campaign, the occupation durations were increased to 12 h a day due to better

battery conditions. The GPS observations were acquired in sample rates of 10 s epochs in

both periods. Both period observations in 2008 and 2010 are processed by GAMIT/

GLOBK academic software.

2.2 Differential InSAR monitoring

There are three alternatives to monitor surface deformations using Differential Radar

Interferometry. These are the X-band radar data with 3.1 cm wavelength, C-band data with

5.6 cm wavelength, and L-band data with 23.6 cm wavelength. The smaller the wave-

length, the better the precision; but the larger the wavelength, the better the penetration of

vegetation and the smaller the influence due to atmosphere and other disturbing effects.

In DInSAR processing, the change of distance between a sensor and the ground can be

measured from phase difference of two observations using phase property in slant-range

length. This change is expressed as follows:

/ ¼ /orbit þ /topo þ /atm þ /def þ /noise ð1Þ

where /orbit is the orbit fringe caused by baseline distance obtained by two observations,

while /topo is the topographic fringe with respect to terrain. These are described by the

following equations

/orbit ¼4pBpara

kð2Þ

Fig. 5 Geodetic control points utilized for monitoring the creep process

2166 Nat Hazards (2013) 65:2161–2173

123

/topo ¼4phBperp

kq sin a: ð3Þ

In these equations, Bpara and Bperp represent parallel and perpendicular components of

baseline, respectively. Also h, k, q, and a represent elevation, wavelength, slant-range

length, and incidence angle, respectively.

/atm is a phase delay caused by reflection of microwave in water vapor layer. It depends

on total electron content of ionosphere and the parameters of the troposphere (Likoka and

Karathanassi 2007). /noise is the error component caused by thermal noise or temporal and

spatial decorrelation associated with baseline distance or scattering characteristic change.

The error component is minimized by applying filtering methods. Finally, /def represents

the amount of surface deformation during the period between two observations (Massonnet

and Feigl 1998; Franceschetti and Lanari 1999; Hanssen 2001; Deguchi et al. 2006). The

whole process of DInSAR processing is summarized in Fig. 6.

In this study, C-band Envisat and L-band Palsar satellite sensors have been preferred to

produce alternative DInSAR solutions. C-band data are more precise than L-band data to

monitor small surface changes, but very sensitive to vegetation, atmosphere and other

noise. On the other hand, L-band data can provide better coherency because it is insensitive

to vegetation, atmosphere, and other noise.

In order to monitor creep motion, 17 Palsar and 22 Envisat data acquired between 2007

and 2010 have been chosen from the related archives. The data obtained have been pro-

cessed on the basis of ‘‘two-pass method’’ of DInSAR technique. SRTM 90 m digital

elevation model data have been used for eliminating topographic effect in phase inter-

ferograms. The deformation interferograms have been then obtained by applying the

weighted power spectrum method for filtering noises (Goldstein and Werner 1998).

Coregistration +

Resampling

Master SLC

Slave SLC

DEM

Generation of interferogram

Simulated interferogram

Flat earth phase

removal

Differential interferogram

Deformation image

Initial interferogram

Topographic phase

Topographic + deformation phase

Fig. 6 DInSAR processing procedure (Kemaldere 2011)

Nat Hazards (2013) 65:2161–2173 2167

123

3 Results

3.1 GPS results

The GPS processing by GAMIT/GLOBK yields to the geodetic network points estimated

with the horizontal accuracy range from 3.2 to 6.3 mm shown in Table 2. According to the

results obtained, the displacements at the object points in the interval of 19 months range

from 1.50 to 2.20 cm and 1.80 to 4.60 cm in the north and east directions, respectively.

Total horizontal displacements range from 2.5 to 5.09. These rates are referenced to ITRF

system. The ITRF-defined displacement rates on Eurasian plate around Turkey are always

larger than the ones on Anatolian block. In this respect, it is understood that the points 5

and 6 stays on the Anatolian block. Figure 7 shows the magnitudes, directions, and error

ellipses of the displacements.

The average displaments are 4.59 ± 0.35 cm on Eurasian side and 2.67 ± 0.46 cm on

Anatolian side. The creep rate of the fault is therefore calculated 2.06 cm during the time

interval of 19 months. On this basis, the yearly creep rate found is 1.30 ± 0.39 cm.

3.2 InSAR results

3.2.1 Palsar results

The highest coherence among the 17 Palsar data has been obtained from 2007/07/04 to

2010/10/12 pairs (Fig. 8). The colors in the figure represent the cycle of the fringes

containing the deformation phase anomalies. In this respect, significant deformation phase

anomalies are observed in the close vicinity of the fault line. These anomalies expose

smooth displacements both sides of the fault along 33 km. This is a consistent charac-

teristic with the aseismic fault creep. The anomalies on the northern side are clearer than

the ones on the southern side. This may be due to the steep topography around the fault line

on the southern side. The fringes on the northern part are lost toward the west after 33 km.

The reason for that may be the creep behavior ending in this part. Another factor may be a

Table 2 Horizontal components of the estimated coordinates and displacements

Point no_year North East Displacement rate (cm)

North East Total

1_2008 4,524,486.09730 ± 5.7 mm 470,667.41754 ± 5.4 mm 2.20 4.10 4.65 ± 0.69

1_2010 4,524,486.11930 ± 4.7 mm 470,667.45883 ± 4.1 mm

2_2008 4,524,930.11130 ± 5.2 mm 470,811.25676 ± 5.7 mm 1.90 4.10 4.52 ± 0.69

2_2010 4,524,930.13000 ± 4.2 mm 470,811.29803 ± 3.9 mm

3_2008 4,524,840.48750 ± 6.1 mm 471,195.21473 ± 6.3 mm 2.20 4.60 5.09 ± 0.80

3_2010 4,524,840.50950 ± 4.2 mm 471,195.26046 ± 5.2 mm

4_2008 4,524,872.83910 ± 5.3 mm 471,657.80201 ± 4.8 mm 1.80 3.70 4.11 ± 0.64

4_2010 4,524,872.85780 ± 4.7 mm 471,657.83907 ± 3.9 mm

5_2008 4,524,497.74780 ± 5.3 mm 471,857.85595 ± 6.6 mm 1.80 2.10 2.77 ± 0.67

5_2010 4,524,497.75880 ± 3.3 mm 471,857.88221 ± 3.2 mm

6_2008 4,524,141.95660 ± 3.9 mm 471,273.31586 ± 6.3 mm 1.50 2.10 2.58 ± 0.65

6_2010 4,524,141.97230 ± 3.2 mm 471,273.33698 ± 3.4 mm

2168 Nat Hazards (2013) 65:2161–2173

123

Fig. 7 Displacements obtained from the Ismetpasa geodetic control points

Fig. 8 Palsar interferogram obtained from 2007/07/04 to 2010/10/12 data pairs. The color bar representingthe cycle of fringe indicates positive range changes along the radar line of sight. One cycle fringecorresponds to 11.8 cm surface displacement

Nat Hazards (2013) 65:2161–2173 2169

123

change in water content of the soil where the geomorphologic feature is alluvial and

relatively flat.

Based on the fringes in the 33-km-long area, the surface displacements are positive on

the north side, but negative on the southern side with respect to the satellite line of sight.

The displacement rates are equivalent on the both sides and measured 2.1 ± 0.7 cm in the

time span of 1,196 days. As a result, the creep rate found is 1.3 ± 0.2 cm a year.

3.2.2 Envisat results

For the Envisat, the data pair of 2007/04/01–2010/10/17 pairs has provided the highest

coherence (Fig. 9). As seen in the figure, similar deformation anomalies to the Palsar have

been detected around the fault line from the Envisat data; however, the precision is better

because the wavelength of the Envisat is shorter than the Palsar. The fringes on the

northern part are lost toward the west after 33 km as it is in the Palsar result, but the ones

on the southern part run 17 km more.

The surface displacements in the time span of 1,295 days are measured 2.2 ± 0.2 cm

eastward for the northern side. The southern part also has the same rate, but moves toward

the west. In this respect, the creep rate is determined 1.2 ± 0.1 cm a year.

Fig. 9 Envisat interferogram obtained from 2007/04/01 to 2010/10/17 data pairs. The color barrepresenting the cycle of fringe indicates positive range changes along the radar line of sight. One cyclefringe corresponds to 2.8 cm surface displacement

2170 Nat Hazards (2013) 65:2161–2173

123

4 Discussion

The Ismetpasa creep has been studied here through two different methods, GPS and

DInSAR, and three different data. The investigations have resulted in 1.3 ± 0.4 cm/year

from GPS, 1.3 ± 0.2 cm/year from Palsar, and 1.2 ± 0.1 cm/year from Envisat. By the

way, Karabacak et al. (2009) and (2011) reported the creep rate of 1.3 ± 0.2 and

1.1 ± 0.2 cm/year, respectively, for the periods 2007–2008 and 2007–2009 using ground-

based LIDAR technology.

All these results are statistically equivalent to each other. In this respect, Fig. 4 which

shows the creep trend can be revised as follows, adding the last determinations in this study

(Fig. 10). In the figure, it is seen that the yearly creep trend is decreased from 1.5 to 1.3 cm

with respect to the previous determination. However, the difference between both results is

not significant because the precision of the previous study is relatively poor as seen in the

figure. On the other hand, it is a fact that a slowing in the creep rate has been observed for

the first time after the 1999 major shocks. This might be an indication of stress starting

increase again.

5 Conclusion

As stated above, the conditions that lead to creep are not well understood (Malservisi et al.

2003; Kanu and Johnson 2011). In this respect, the creep behavior of the Ismetpasa

segment can help us to understand these conditions. The former efforts showed that its

creep rate decreased and then accelerated before and after the Kocaeli earthquake. In

Kutoglu et al. (2010), it was claimed that this behavior would be repeated before the next

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 20100.5

1

1.5

2

2.5

3

Year

Cre

ep r

ate

(cm

/yea

r)

Aytun 1982triangulation

Eren 1984Doppler trilateration Deniz 1993

EDM trilateration

Ambraseys 1970wall offset

Cakir et. al. 2005InSAR

Kutoglu and Akcin 2006GPS network

Kutoglu et. al. 2008GPS network

Kutoglu et. al. 2010GPS network

This studyGPS and InSAR

17 August 1999Mw=7.6 Kocaeli Earthquake

Fig. 10 Creep rates after the last determinations. The blue vertical lines at data points are error bars

Nat Hazards (2013) 65:2161–2173 2171

123

major earthquake. Now, the results in this study reveal that the creep rate has slowed after

the 10 years acceleration. Interestingly, the north branch of the NAF in the Marmara sea

experienced an earthquake with Mw = 5.2 in 2011. This segment has not experienced any

earthquakes\Mw = 5 since the 1999 major shock. These events can be either coincidental

or the precursor of the increasing stress in the segment. In this respect, the creep behavior

in future would be decisive. If the segment retains the slowing trend, this might be a

precursor for the expected major earthquake in the Marmara Region.

Acknowledgments European Space Agency supports Hazard Monitoring & Research Laboratory ofDepartment of Geodesy and Photogrammetry at ZKU with the project C1P.7390 for the investigations onthe Ismetpasa segment of the North Anatolian Fault. The authors thank to Delft Institute of Earth Obser-vation and Space Systems, Delft University of Technology and Department of Earth Atmospheric andPlanetary Sciences, Massachusetts Institute of Technology for providing DORIS and GAMIT/GLOBKsoftwares. In the research team, Dr. Hakan S. Kutoglu is the instructor of the project and has interpreted theresults of GPS and InSAR. Dr. Kurtulus S. Gormus has carried out the GPS processing. DInSAR processeshave been done by Dr. Tomonori Deguchi, Dr. Eray Koksal, and Dr. Huseyin Kemaldere. Dr. OguzGundogdu has made the geophysical contributions.

References

Allen CR (1969) Active faulting in northern Turkey. Div Geol Sci Calif Inst Technol Contrib 1577:32Altay C, Sav H (1991) Continuous creep measurement along the North Anatolian Fault zone. Bull Geol

Congr Turk 6:77–84Ambraseys NN (1970) Some characteristic features of the Anatolian Fault zone. Techtonophysics 9:

143–165Aytun A (1982) Creep measurements in the Ismetpasa region of the North Anatolian Fault zone. In: Isikara

AM, Vogel A (eds) Multidisciplinary approach to earthquake prediction 2. Friedr. Vieweg & Sohn,Braunschweig, pp 279–292

Barka A (1992) The North Anatolian Fault zone. Ann Tecton VI suppl.:164–195Barka A (1996) Slip distribution along the rupture zones of the 1939–1967 large earthquake migration in the

North Anatolian Fault. Bull Seismol Soc Am 86:1238–1254Bilham R, Suszek N, Pinkney S (2004) California creepmeters. Seismol Res Lett 75:481–492Cakir Z, Akoglu AM, Belabbes S, Ergintav S, Meghraoui M (2005) Creeping along the Ismetpasa section of

the North Anatolian Fault (Western Turkey): rate and extent from InSAR. Earth Plan Sci Lett238:225–234

Deguchi T, Kato M, Akcin H, Kutoglu HS (2006) Automatic processing of interferometric SAR andaccuracy of surface deformation measurement. SPIE Europe Remote Sensing, Stockholm

Deniz R, Aksoy A, Yalin D, Seeger H, Hirsch O (1993) Determination of crustal movement in Turkey byterrestrial geodetic methods. J Geodyn 18:13–22

Dewey JW (1976) Seismicity of northern Anatolia. Bull Seismol Soc Am 66:843–868Eckl MC, Snay RA, Soler T, Cline MW, Mader GL (2001) Accuracy of GPS-derived relative positions as a

function of interstation distance and observing-session duration. J Geodesy 75:633–640Eren K (1984) Strain analysis along the North Anatolian Fault by using geodetic surveys. Bull Geod

58:137–149Even-Tzur G, Salmon E, Kozakov M, Rosenblum M (2004) Designing a geodetic-geodynamic network: a

comparative study of data processing tools. GPS Solut 8:30–35Franceschetti G, Lanari R (1999) Synthetic aperture radar processing. CRC Press, New YorkGalehouse J (1992) Theodolite measurements of creep rates on San Francisco Bay region faults. US Geol

Surv Open File Rep 92–258:256–261Goldstein RM, Werner CL (1998) Radar interferogram filtering for geophysical applications. Geophys Res

Lett 25(21):4035–4038Gurtner W (1993) The use of IGS products for densifications of regional/local networks. EUREF Sympo-

sium, Budapest, 17–19 MayHanssen RF (2001) Radar interferometry: data interpretation and error analysis. Springer, New YorkHofmann-Wellenhof B, Lichtenegger H, Collins J (1997) GPS theory and practice, 4th edn. Springer,

New York

2172 Nat Hazards (2013) 65:2161–2173

123

Kanu C, Johnson K (2011) Arrest and recovery of frictional creep on the southern Hayward fault triggeredby the 1989 Loma Prieta, California, earthquake and implications for the future earthquakes. J GeophysRes 116:B04403. doi:10.1029/2010JB007927

Karabacak V, Cakir Z, Altunel E, Yonlu O (2009) Determination of creep with using ground based LIDARsystem on North Anatolian Fault Zone. 62nd Geological Congress of Turkey, 13–17 April, Ankara

Karabacak V, Altunel E, Cakir Z (2011) Monitoring aseismic surface creep along the North Anatolian Fault(Turkey) using ground-based LIDAR. Earth Planet Sci Let 304:64–70

Kemaldere H (2011) Monitoring of undercity mining and subsidence effect by differential InSAR techniquein Zonguldak Metropolitan Area. Ph.D. thesis, Zonguldak Karaelmas University (In Turkish)

Ketin I (1969) Uber die nordanatolische Horizontalverschiebung. Bull Min Res Explor Inst Turk 72(1–28):1969

Kutoglu HS (2010) Datum issue in deformation monitoring using GPS. FIG working week 2010-facing thechallenges, Sydney, 11–16 April 2010

Kutoglu HS, Akcin H (2006) Determination of 30-year creep on the Ismetpasa segment of the NorthAnatolian Fault using an old geodetic network. Earth Planet Space 58:937–942

Kutoglu HS, Akcin H, Kemaldere H, Gormus KS (2008) Triggered creep rate on the Ismetpasa segment ofthe North Anatolian Fault. Nat Hazards Eart Syst Sci 8:1369–1373

Kutoglu HS, Akcin H, Gundogdu O, Gormus KS, Koksal E (2010) Relaxation on the Ismetpasa segment ofthe North Anatolian Fault after the Golcuk Mw = 7.4 and Duzce Mw = 7.2 shocks. Nat Hazards EartSyst Sci 10:2653–2657

Lienkaemper J, Borchart G, Lisowski M (1991) Historic creep rate and potential for seismic slip along theHayward fault. Calif J Geophys Res 96(B11):18261–18283

Likoka SA, Karathanassi V (2007) A statistical analysis of the error produced by the tropospheric path delaycalculation. In: Proceeding of Envisat symposium, 23–27 April 2007, Montreux, Switzerland

Malservisi R, Gans C, Furlong KP (2003) Numerical modeling of strike-slip creeping faults and implicationsfor the Hayward fault, California. Tectonophsics 361:121–137

Massonnet D, Feigl KL (1998) Radar interferometry and its application on changes in the earth’s surface.Rev Geophys 36(4):441–500

McClusky S, Balassanian S, Barka AA, Demir C, Ergintav S, Georgiev I, Gurkan O, Hamburger M, Hurst K,Kahle H, Kastens K, Kekelidze G, King R, Kotsev V, Lenk O, Mahmoud S, Nadariya M, Ouzounis A,Paradissis D, Peter Y, Prilepin M, Reilinger RE, Burgmann R, McClusky S, Lenk O, Barka A, Gurkan O,Hearn L, Feigl KL, Cakmak R, Aktug B, Ozener H, Toksoz MN (2000) Coseismic and postseismic faultslip for the 17 August 1999, M = 7.5, Golcuk, Turkey earthquake. Science 289:1519–1523

Parsons T (2004) Recalculated probability of M_7 earthquakes beneath the Sea of Marmara, Turkey.J Geophys Res 109:B05304. doi:10.1029/2003JB002667

Parsons T, Toda S, Stein RS, Barka A, Dieterich JH (2000) Heightened odds of large earthquakes nearIstanbul: an interaction-basedprobability calculation. Science 288:661–665

Press F (1975) Earthquake prediction. Sci Am 232:14–23Psimoulis PA, Kontogianni VA, Nickitopoulou, Pytharoulli SI, Trantafyllidis P, Stiros SC (2004) Estimating

the optimum duration of GPS static observations for short baseline length determination in Greece. FIGWorking Week 2004, Athens, Greece 22–27 May

Reilinger R, Sanli I, Seeger H, Tealeb A, Toksoz MN, Veis G (2000) Global Positioning system constraintson plate kinematics and dynamics in the eastern Mediterranean and Caucasus. J Geophys Res 105:5695–5719

Saroglu F, Kuscu I (1992) Active Fault Map of Turkey (1:1,000,000). General Directorate of MineralResearch and Exploration (MTA), Ankara

Sengor AMC, Gorur N, Saroglu F (1985) Strike-slip faulting and related basin formation in zones of tectonicescape: Turkey as a case study. In: Biddke KT, Christie-Blick N (eds) Strike-slip faulting and basinformation. Society of Economic Paleontologists and Mineralogists, Special Publications, pp 227–264

Stein RS, Barka A, Dieterich JH (1997) Progressive failure on the North Anatolian Fault since 1939 byearthquake stress triggering. Geophys J Int 128:594–604

Sylvester AG (1988) Strike-slip faults. Geol Soc Am Bull 100:1666–1703Teunissen PJG, Kleusburg A (1998) GPS for Geodesy. Springer, GermanyUgur E (1974) Analysis of the Crustal Movements along the North Anatolian Fault Using Geodetic

Methods. PhD thesis, Istanbul Technical University, Istanbul, TurkeyWesley VH (1989) Geometric Geodetic accuracy standards and specifications for using GPS relative

Positioning Techniques. Federal Geodetic Control Committee

Nat Hazards (2013) 65:2161–2173 2173

123