Crustal-scale shear zones and heterogeneous structure beneath the North Anatolian Fault Zone, Turkey, revealed by a high-density seismometer array

Kahraman, M.; Cornwell, David G.; Thompson, David; Rost, Sebastian; Houseman, Gregory A.; Türkelli, N.; Teoman, U.; Poyraz, Selda Altuncu; Utkucu, Murat; Gülen, Levent

doi:10.1016/j.epsl.2015.08.014

Cited by 41 publications

(75 citation statements)

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“…The presence of different lithologies bounding the northern branch of the NAFZ (NNAF) has been inferred by Bulut et al () and Najdahmadi et al () by tracking fault head waves caused by the presence of a bimaterial interface. This is also consistent with a change in Moho signature and depth observed in the Istanbul Zone and has been attributed to either the presence of a thicker crust (Frederiksen et al, ) or a weak Moho underlain by a highly anisotropic layer (Kahraman et al, ). These observations support the idea that a clear separation between the north Anatolian province and the central Anatolian province exists across the northern NAFZ.…”

Section: Introductionsupporting

confidence: 86%

“…These observations support the idea that a clear separation between the north Anatolian province and the central Anatolian province exists across the northern NAFZ. Receiver function and autocorrelation studies (Kahraman et al, ; Taylor et al, ) reported truncation of several subhorizontal structures throughout the crust beneath both NAFZ strands. Furthermore, an absence of Moho signature beneath the northern NAFZ may indicate a fault zone rooted in the upper mantle (Kahraman et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Receiver function and autocorrelation studies (Kahraman et al, ; Taylor et al, ) reported truncation of several subhorizontal structures throughout the crust beneath both NAFZ strands. Furthermore, an absence of Moho signature beneath the northern NAFZ may indicate a fault zone rooted in the upper mantle (Kahraman et al, ). Results from P wave teleseismic tomography in the same area (Papaleo et al, ) provided the first direct evidence for a narrow (<50 km) fault zone that extends into the upper mantle to a depth of at least 80 km beneath the NNAF.…”

Section: Introductionmentioning

confidence: 99%

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Constraints on North Anatolian Fault Zone Width in the Crust and Upper Mantle From S Wave Teleseismic Tomography

2018

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We present high‐resolution S wave teleseismic tomography images of the western segment of the North Anatolian Fault Zone (NAFZ) in Turkey using teleseismic data recorded during the deployment period of the Dense Array for Northern Anatolia array. The array comprised 66 stations with a nominal station spacing of 7 km, thus permitting a horizontal and vertical resolution of approximately 15 km. We use the current S wave results with previously published P wave teleseismic tomography to produce maps of relative VP/VS anomalies, which we use to highlight the difference in overall composition of the three terranes separated by the northern (NNAF) and southern branches of the NAFZ. Our results show a narrow S wave low‐velocity anomaly beneath the northern branch of the NAFZ extending from the upper crust, where it has a width of ∼10 km, to the lower crust, where it widens to ∼30 km. This low‐velocity zone most likely extends into the upper mantle, where we constrain its width to be ≤ 50 km and interpret it as indicative of localized shear beneath the NNAF; this structure is similar to what has been observed for the NAFZ west of 32°, and therefore, we propose that the structure of the NNAF is similar to that of the NAFZ in the east. The southern branch of the NAFZ does not show a very strong signature in our images, and we conclude that it is most likely rooted in the crust, possibly accommodating deformation related to rotation of the Armutlu/Almacik Blocks situated between the two NAFZ branches.

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Section: Introductionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraints on North Anatolian Fault Zone Width in the Crust and Upper Mantle From S Wave Teleseismic Tomography

2018

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“…With colleagues in Leeds, Aberdeen and at the Kandilli Observatory in Istanbul, we have been conducting a highresolution seismic experiment to image the deep structure of the North Anatolian Fault in the location that failed in the 1999 earthquakes (DANA, 2012). Preliminary results from receiver functions also suggest sharp changes in crustal properties across the two major fault strands in the location of the survey (Kahraman et al, 2015). Further work is needed to understand how such shear zones develop, and whether similar weak zones exist under extensional and thrust faults in the continents.…”

Section: Towards a Practical Seismicity Forecast From Geodetic Strainmentioning

confidence: 99%

The earthquake deformation cycle

Wright

2016

A&G

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Abstract/Intro Paragraph.Earthquakes seem impossible to predict, yet they are associated with the slow deformation of tectonic plates. In the 2015 Bullerwell lecture, Tim Wright reviews observations of time-dependent surface deformation in fault zones, and uses these observations to place constraints on feasible models of the earthquake deformation cycle. The results have implications for the mechanics of fault zones and the strength of the continental lithosphere, and are critical if we are to use short-term geodetic observations as tool for assessing seismic hazard.

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“…Vanocore et al (2013) measured the MOHO depth as 55 km for the East Anatolia, as 37-47 km for the Central Anatolia and much thinner for the West Anatolia using receiver function. Kahraman et al (2015) have shown lithological and structural variations in lower, middle and upper crusts by means of the receiver function. Pamukçu et al (2007) in their studies determined the crustal thickness nearly 45 km.…”

Section: Introductionmentioning

confidence: 99%

GEOPHYSICAL REGIONAL GRAVITY MAP of TURKEY and ITS GENERAL ASSESSMENT

Akin¹

2016

Bulletin of the Mineral Research and Exploration

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In this study, the apparent gravity density data was measured for Turkey using apparent density filter, and the seismic velocity distribution map was generated from this data cluster. By interpreting these two measured data clusters, three dimensional structure of the Conrad discontinuity was investigated. The apparent gravity filter is a kind of filter which is used in the apparent gravity measurements for different depth levels different than gravity data. In this study, considering previously measured distribution of the continental crustal thickness of the Anatolia, the density maps for different depth levels were formed and interpreted. The lowest and highest densities in different levels of Turkey are 2.23 gr/cm 3 , and 3 gr/cm 3 , respectively; and the mean density is 2.698 gr/cm 3 . The lowest and highest seismic velocities for different thicknesses were measured as 3.20 km/sec and 6.83 km/sec, respectively. However; the mean seismic velocity of Turkey for depths increasing up to 10 km until MOHO discontinuity was estimated as 5.66 km/sec. The density and seismic velocity in the first 20 km of the continental crust have reached its highest values as 2.74 gr/cm 3 and 5.86 km/sec, respectively. This zone is also the Conrad discontinuity between the lower and upper crusts, and its average depth is 16 km in Turkey. The Conrad discontinuity boundary, which developed between SIAL-SIMA, not to be observed in the East Anatolian High Plateau made us consider that SIMA had disappeared as a result of the geological evolution, and the available crust could only be SIAL in origin.

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Crustal-scale shear zones and heterogeneous structure beneath the North Anatolian Fault Zone, Turkey, revealed by a high-density seismometer array

Cited by 41 publications

References 45 publications

Constraints on North Anatolian Fault Zone Width in the Crust and Upper Mantle From S Wave Teleseismic Tomography

Constraints on North Anatolian Fault Zone Width in the Crust and Upper Mantle From S Wave Teleseismic Tomography

The earthquake deformation cycle

GEOPHYSICAL REGIONAL GRAVITY MAP of TURKEY and ITS GENERAL ASSESSMENT

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