Relaxation on the Ismetpasa segment of the North Anatolian Fault after the Golcuk &amp;lt;i&amp;gt;M&amp;lt;/i&amp;gt;&amp;lt;sub&amp;gt;w&amp;lt;/sub&amp;gt; = 7.4 and Duzce &amp;lt;i&amp;gt;M&amp;lt;/i&amp;gt;&amp;lt;sub&amp;gt;w&amp;lt;/sub&amp;gt; = 7.2 shocks

Kutoğlu, Şenol Hakan; Akçın, Hakan; Gündoğdu, Oğuz; Gormus, K. S.; Koksal, E.

doi:10.5194/nhess-10-2653-2010

Cited by 11 publications

(17 citation statements)

References 11 publications

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“…However, some authors have claimed significant changes in rate based on the apparent outliers evident in Figure b. These are labeled K8 [ Kutoglu et al ., ] and K10 [ Kutoglu et al ., ] that we now briefly discuss. The two time intervals with high velocities recorded are 5 and 6 years duration with velocities of 12.0 ± 1.3 and 15.1 ± 4.1, respectively, preceded by a contiguous 10 year interval with 6.7 ± 1.1 mm/yr velocity (K6), suggesting an acceleration in slip rate in the interval 1992–2008 (Table ).…”

Section: Discussionmentioning

confidence: 99%

“…It is possible that this earthquake may have locally shifted the control points analyzed by Kutoglu et al . [, , ].…”

Section: Discussionmentioning

confidence: 99%

“…No perturbations in slip rate are evident in the data following several nearby earthquakes on the fault or the 1999 earthquakes [ Kutoglu et al ., , ]; however, wall offsets are constrained between 1984 and 2007 by a single point in 1995 devoid of a photographic record or stated uncertainty [ Şaroğlu and Barka , ]. We discuss next the occurrence of large creep events recorded by creep meters at Ismetpasa whose unrecorded occurrence would result in apparent accelerations in rate that will have escaped notice in the sparse photographic record.…”

Section: The 1957 Wall At Ismetpasamentioning

confidence: 99%

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Surface creep on the North Anatolian Fault at Ismetpasa, Turkey, 1944–2016

et al. 2016

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We reevaluate the 72 year history of surface slip on the North Anatolian Fault at Ismetpasa since the Mw = 7.4 1944 Bolu/Gerede earthquake. A revised analysis of published observations suggests that days after the earthquake the fault had been offset by 3.7 m and 6 years later by an additional 0.74 m. Creep was first recognized on the fault in 1969 as a 0.13 m offset of a wall constructed in 1957 that now (2016) has been offset by 0.52 m. A carbon rod creep meter operated across the fault in the past 2 years confirms results from an invar wire creep meter operated 1982–1991 that surface slip is episodic. Months of fault inactivity are interrupted by slow slip (≤10 µm/d) or multiple creep events with cumulative amplitudes of 2–10 mm, durations of several weeks, and with slip rates briefly exceeding >2.5 mm/h. Creep events accommodate 80% of the surface slip and individually release ≈ 10−6 shear strain on the flanks of the uppermost 3–7 km of the fault. GPS and interferometric synthetic aperture radar methods yield a current fault slip rate of 7.6 ± 1 mm/yr suggesting that creep meters incompletely sample the full width of the surface shear zone. The slip rate has slowed from >10 mm/yr in 1969 to 6.1 mm/yr at present, 4.65 mm/yr of which appears to be due to steady interseismic creep driven by plate boundary stressing rates. We calculate that a further 1 m of aseismic surface slip will precede the next major earthquake on the fault assuming an ≈ 260 year main shock recurrence interval on this segment.

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Section: Discussionmentioning

confidence: 99%

“…It is possible that this earthquake may have locally shifted the control points analyzed by Kutoglu et al . [, , ].…”

Section: Discussionmentioning

confidence: 99%

Section: The 1957 Wall At Ismetpasamentioning

confidence: 99%

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Surface creep on the North Anatolian Fault at Ismetpasa, Turkey, 1944–2016

et al. 2016

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“…The first measurements of aseismic creep along this section of the fault were made by Ambraseys [1970], who estimated a creep rate of ∼20 mm/yr near the town of Ismetpasa. Although it is not known whether the fault was creeping before the 1944 earthquake, numerous studies have shown that the surface creep rate follows an exponential decay through time to a current steady state value of ∼8 mm/yr [e.g., Cakir et al, 2005;Kutoglu et al, 2010;Kaneko et al, 2013;Cetin et al, 2014], implying that aseismic creep was initiated as postseismic deformation following the large earthquake. Cetin et al [2014] also showed that aseismic surface creep can, to some extent, be correlated with the geology along the North Anatolian Fault.…”

Section: Fault Creepmentioning

confidence: 99%

“…Ambraseys [1970] estimated a fault creep rate of ∼20 mm/yr for the time period [1955][1956][1957][1958][1959][1960][1961][1962][1963][1964][1965][1966][1967][1968][1969]. Since this original investigation, the fault creep has been the focus of numerous geodetic studies [e.g., Cakir et al, 2005;Kutoglu et al, 2010;Karabacak et al, 2011;Ozener et al, 2013;Cetin et al, 2014]. Cetin et al [2014] suggested that the fault creep rate has been decaying since the first measurements in 1970 to a current steady state value of ∼6-8 mm/yr.…”

Section: Introductionmentioning

confidence: 99%

Interseismic strain accumulation across the central North Anatolian Fault from iteratively unwrapped InSAR measurements

et al. 2016

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The North Anatolian Fault (NAF) is a major tectonic feature in the Middle East and is the most active fault in Turkey. The central portion of the NAF is a region of Global Navigation Satellite Systems (GNSS) scarcity. Previous studies of interseismic deformation have focused on the aseismic creep near the town of Ismetpasa using radar data acquired in a single line‐of‐sight direction, requiring several modeling assumptions. We have measured interseismic deformation across the NAF using both ascending and descending data from the Envisat satellite mission acquired between 2003 and 2010. Rather than rejecting incorrectly unwrapped areas in the interferograms, we develop a new iterative unwrapping procedure for small baseline interferometric synthetic aperture radar (InSAR) processing that expands the spatial coverage. Our method corrects unwrapping errors iteratively and increases the robustness of the unwrapping procedure. We remove long wavelength trends from the InSAR data using GNSS observations and deconvolve the InSAR velocities into fault‐parallel motion. Profiles of fault‐parallel velocity reveal a systematic eastward decrease in fault slip rate from 30 mm/yr (25–34, 95% confidence interval (CI)) to 21 mm/yr (14–27, 95% CI) over a distance of ∼200 km. Direct offset measurements across the fault reveal fault creep along a ∼130 km section of the central NAF, with an average creep rate of 8 ± 2 mm/yr and a maximum creep rate of 14 ± 2 mm/yr located ∼30 km east of Ismetpasa. As fault creep is releasing only 30–40% of the long‐term strain in the shallow crust, the fault is still capable of producing large, damaging earthquakes in this region.

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Extent and distribution of aseismic slip on the Ismetpaşa segment of the North Anatolian Fault (Turkey) from Persistent Scatterer InSAR

Çetin

Çakır

Meghraoui

et al. 2014

Geochem Geophys Geosyst

126

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We use the Persistent Scatterer InSAR (PSI) technique with elastic dislocation models and geology along the creeping section of the North Anatolian Fault (NAF) at Ismetpas¸a, to map and deduce the velocity field and the aseismic slip distribution. Revealing the spatiotemporal nature of the creep helped us associate the creep with potential lithological controls, hence providing a new perspective to better understand the underlying causes and mechanisms. The PSI analysis of Envisat ASAR images between 2003 and 2010 reveals a clear picture of surface creep along the fault and a new interseismic velocity field transitioning gradually between the creeping and the locked fault sections. The creep rate is found to fluctuate along a 100 km long section of the fault in a manner similar to that along the Hayward fault, reaching a maximum of 20 6 2 mm/yr, close to the far field plate velocity (25 6 1.5 mm/yr). At Ismetpas¸a, it is in the range of 8 6 2 mm/yr, consistent with the previous geodetic observations. The creeping section appears to extend 30 km further east than those previously reported. Modeling of the PSI data reveals a heterogeneous creep distribution at depth with two main patches confined mostly to the uppermost 5 km portion of the seismogenic crust, releasing annually 6.2 3 10 16 Nm (Mw 5 5.1) geodetic moment. Our analysis combined with previous studies suggests that creep might have commenced as postseismic deformation following the 1944 earthquake and has evolved to stable fault creep with time. There is a correlation between aseismic surface creep and the geology along the fault as it is in major part associated to rocks with low frictional strength such as the andesitic-basaltic, limestone, and serpentine bodies within the fault zone.

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Relaxation on the Ismetpasa segment of the North Anatolian Fault after the Golcuk <i>M</i><sub>w</sub> = 7.4 and Duzce <i>M</i><sub>w</sub> = 7.2 shocks

Cited by 11 publications

References 11 publications

Surface creep on the North Anatolian Fault at Ismetpasa, Turkey, 1944–2016

Surface creep on the North Anatolian Fault at Ismetpasa, Turkey, 1944–2016

Interseismic strain accumulation across the central North Anatolian Fault from iteratively unwrapped InSAR measurements

Extent and distribution of aseismic slip on the Ismetpaşa segment of the North Anatolian Fault (Turkey) from Persistent Scatterer InSAR

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