Determination of the deep fault geometry along the southern branch of the North Anatolian Fault System by using resistivity and magnetic methods

Aşçı, Metin; Dogan, Bulent; Yas, Türker; Ćaka, Deniz

doi:10.1016/j.jseaes.2016.05.020

“…Tank et al (2005) have determined that a high resistivity conductive zone indicates the fault plane where the mainshock and aftershocks of 17 August 1999 Izmit earthquake occurred. In the same region, Aşcı et al (2016) have revealed by conducting resistivity and magnetic studies along the NAFS-SB, that the strike-slip faults deformed the region during the Plio-Quaternary period. Also, the ERT method was applied for both the distribution of faults and determination of Quaternary deposit thickness on the Paganica-San Demetrio normal fault system (Pucci et al 2016).…”

Section: Relationship Between Basins Edge (Secondary) Faults and Regional Active Tectonicsmentioning

confidence: 92%

Basin progress: active deformation analysis by tectonostratigraphic elements and geophysical methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

Dogan

¹

,

Aşçı

²

,

Karakaş

³

et al. 2021

Nat Hazards

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The Northern Branch of the North Anatolian Fault System controls and deforms the Izmit Basin and the Sapanca Lake Basin in the study area. Unlike the Sapanca Lake Basin, the oblique normal faults with WNW-ESE trending with maximum length of 5 km in the south of the basin have contributed to the deformation process in the formation of Izmit Basin. The fault sets mainly incline to the north. The N-S width of the dextral strike-slip active deformation was determined as 9 km at Izmit basin and 3.8 km at Sapanca Lake basin. Further, the minimum principal stress axes (σ3) vary in the trending ranges of N11°-74° E, which are caused by the transtensional stresses associated with strikeslip faulting in the Izmit Basin by a different tectonic source than the Sapanca Lake Basin. Besides, the crust depth of main strand of NAFS-NB was determined up to 1112 m by magnetic method. The secondary faults were determined by both magnetic and resistivity methods up to a depth of 110 m. The depression area between Izmit bay and Sapanca Lake on the northern Anatolian fault is an integrated basin with two dextral strike-slip tectonic origins. Thus, the Izmit Basin, along with the main strike-slip faulting, has been developed in the asymmetric negative ower structure, where only the southern boundary has become a fault. The Sapanca Lake Basin is a lazy-Z-shaped pull-apart system formed by the E-W trending fault as a releasing bend. A simple shear deformation ellipsoid with a long axis of approximately 35 km on the Northern Branch of the North Anatolian Fault System is de ned for the Izmit -Sapanca integrated basin. Therefore, intra-basin deposits have different depths estimated from the gravity data in the Izmit -Sapanca integrated basin, and the maximum sediment thickness estimated is 2200 m in the middle of the Izmit Basin. Ogawa et al. 2001; Ogawa and Honkura 2004). Ateş et al. (2003) have identi ed the faults in the deep section of the crust along the NAFS-NB based on the high-speed zones and the regions where coincident with gravity and magnetic highs. Bohnhoff et al. (2016b), suggested that a coseismically introduced lateral and vertical slip de cit is systematically compensated postseismically in both the brittle and ductile portions of the crust in east Marmara region.This study explains the development of an integrated basin-like ISIB consisting of Izmit basin and Sapanca Lake basin with different basin morphology, located on a right-lateral strike-slip fault (NAFS). In this sense, the deformation geometry of the active structural elements, which are associated with lithofacies features, the sedimentary processes of the basin-lling formations, and which are different from each other in each basin, are formed from the surface to a certain depth of the upper crust. The tectonostratigraphic observations made on the surface were correlated with the geophysical data collected by the resistivity, magnetic, gravity, and joint inversion methods, identi ed the traces of active deformation in the upper depths of the ISIB. Thus, the charac...

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Investigating of soil features and landslide risk in Western-Atakent (İstanbul) using resistivity, MASW, Microtremor and boreholes methods

Keskinsezer¹,

Dağ²

2019

Open Geosciences

5

0

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In Western-Atakent (İstanbul), population density is increasing day by day and settlement areas are expanding. Soil properties and landslide conditions of these expanding regions must be absolutely examined. In the geophysics, there are many methods used to investigate landslide risks and geotechnical structure. The most common geophysical methods used for this purpose are the Electrical resistivity tomography (ERT), Multi-channel Analysis of Surface Waves (MASW) and Microtremor Survey Method (MSM) methods. These methods are very successful techniques for defining underground layers as geological structures, stratigraphic elements, soil layer thickness and landslide. Because of that reason in this study, soil properties and possibility of landslides of the Western-Atakent (İstanbul) region were investigated by using ERT, MASW, MSM and drilling methods. In this study the first stage, electrical resistivity data have been measured using dipole-dipole method on two profiles for ERT. In the second stage, MASW measurements have been made at 25 points on 5 seismic profiles in the field. In the third stage, MSM measurements have been made to determine the fundamental period in the 5-measure station in the study area. In the fourth and final stage, 10-pieces boreholes with a depth of 20 m were drilled to reveal the lithological structure of the study area. As a result of the evaluation of all data, parts of the region that could form landslides were revealed.

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Basin Progress – Active Deformation Analysis by Tectonostratigraphic Elements and Geophysical Methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

Dogan

¹

,

Aşçı

²

,

Karakaş

³

et al. 2021

Preprint

0

View full text Add to dashboard Cite

The Northern Branch of the North Anatolian Fault System controls and deforms the Izmit Basin and the Sapanca Lake Basin in the study area. Unlike the Sapanca Lake Basin, the oblique normal faults with WNW–ESE trending with maximum length of 5 km in the south of the basin have contributed to the deformation process in the formation of Izmit Basin. The fault sets mainly incline to the north. The N-S width of the dextral strike-slip active deformation was determined as 9 km at Izmit basin and 3.8 km at Sapanca Lake basin. Further, the minimum principal stress axes (σ3) vary in the trending ranges of N11°-74° E, which are caused by the transtensional stresses associated with strike-slip faulting in the Izmit Basin by a different tectonic source than the Sapanca Lake Basin. Besides, the crust depth of main strand of NAFS-NB was determined up to 1112 m by magnetic method. The secondary faults were determined by both magnetic and resistivity methods up to a depth of 110 m. The depression area between Izmit bay and Sapanca Lake on the northern Anatolian fault is an integrated basin with two dextral strike-slip tectonic origins. Thus, the Izmit Basin, along with the main strike-slip faulting, has been developed in the asymmetric negative flower structure, where only the southern boundary has become a fault. The Sapanca Lake Basin is a lazy-Z-shaped pull-apart system formed by the E–W trending fault as a releasing bend. A simple shear deformation ellipsoid with a long axis of approximately 35 km on the Northern Branch of the North Anatolian Fault System is defined for the Izmit – Sapanca integrated basin. Therefore, intra-basin deposits have different depths estimated from the gravity data in the Izmit – Sapanca integrated basin, and the maximum sediment thickness estimated is 2200 m in the middle of the Izmit Basin.

show abstract

Determination of the deep fault geometry along the southern branch of the North Anatolian Fault System by using resistivity and magnetic methods

Cited by 3 publications

References 29 publications

Basin progress: active deformation analysis by tectonostratigraphic elements and geophysical methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

Basin progress: active deformation analysis by tectonostratigraphic elements and geophysical methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

Investigating of soil features and landslide risk in Western-Atakent (İstanbul) using resistivity, MASW, Microtremor and boreholes methods

Basin Progress – Active Deformation Analysis by Tectonostratigraphic Elements and Geophysical Methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

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