Evaluation of site effect within the tectonic basin in the northern side of Ankara

Eker, Arif Mert
Kockar, Mustafa Kerem
Akgün, Haluk
This study mainly concentrates on the determination of site effects for the Plio-Quaternary and especially alluvial soils of the Cubuk district and its close vicinity in Ankara, Turkey. In the study area, particularly in the vicinity of the asymmetric graben that has formed due to the tectonic activities along the NE-SW trending normal faults, a microtremor survey was implemented to identify the local site response under a possible seismic event. The results were compared and correlated by using passive and active surface wave measurements, engineering geological and geotechnical deep borehole logs along with information on local geology and geological tectonic setting. Regarding the microtremor results, larger fundamental periods were acquired than expected over the area and the effect of the tectonic deformation on the stiffness of the soils was also observed at either the H/V curves or the shear wave velocity profiles. The results have demonstrated that geotechnical information down to a depth of 30 m may not be compared with the H/V parameters. The H/V amplitudes were not always accompanied with the higher periods in the Quaternary sediments. This could be due to the basin and basin edge effects observed particularly at the center and boundary of the basin, respectively. Additionally, the microtremor survey showed that the spectral ratio amplitudes derived by the H/V ratio are debatable and are not a direct indicator of local soil behavior under a seismic excitation.


A Comprehensive Study to Define Local Site Effects in Northern Ankara Turkey
Eker, Arif Mert; Akgün, Haluk; Koçkar, Mustafa Kerem (null; 2013-05-31)
The study is mainly focused on the dynamic soil characterization and determination of site effects for the PlioQuaternary and especially alluvial soils of the Çubuk district and its close vicinity in Ankara. It was observed that the shear wave velocity values for the uppermost 30 meter of the soil profile is not adequate to classify the sites properly and these values could not be correlated with the H/V results obtained from the microtremor records due to the great thicknesses of the soft sediments. The hi...
Evaluation of Site Characterizations and Site Effects of the Ankara Basin Turkey
Koçkar, Mustafa Kerem; Akgün, Haluk (2007-06-28)
The purpose of this study is to assess the in-situ site characteristics and to perform seismic hazard studies of the Upper Pliocene to Pleistocene fluvial and Quaternary alluvial and terrace deposits located towards the west of Ankara. Based on a general engineering geological, geotechnical and seismic characterization of the site, site classification systems were assigned for seismic hazard evaluations. Then, short-period noise recordings of the microtremor measurements at the ground surface have been used...
Integration of Surface Wave Seismic Survey Testing Results and Segmented Seismic Source Model of NAFS for PSHA of the Gölyaka Düzce Tectonic Basin Turkey(2005)
Yousefibavil, Karim; Akgün, Haluk; Eker, Arif Mert; Cambazoğlu, Selim; Koçkar, Mustafa Kerem (null; 2015-11-04)
This study mainly focuses on the determination of site effects for the Plio-Quaternary sediments of Gölyaka-Düzce, Turkey by characterizing local soil conditions. Probabilistic seismic hazard assessment (PSHA) analysis was performed to observe the effect and importance of local site conditions. The study area is located within the Eastern Marmara Region and uniquely falls within the bifurcated section of the North Anatolian Fault System (NAFS). This tectonic basin is bounded by the surface rupture of the 19...
Evaluation of site effects based on the 1999 Kocaeli and Düzce earthquake events and seismic microzonation of Gölyaka, Düzce, Turkey
YOUSEFI BAVIL, KARIM; Akgün, Haluk; Koçkar, Mustafa Kerem; Department of Geological Engineering (2022-2)
The high seismicity study area situated in a near-fault region in Gölyaka, Düzce, makes the determination of the bedrock geometry more complex, and hence, it makes this area very challenging in terms of a site response study that would aid a seismic hazard assessment. This study developed a basin model to evaluate the site effects in the tectonically controlled and formed Plio-Quaternary fluvial sediments of the Gölyaka region that uniquely falls within the bifurcated near-field fault section of the North A...
Analysis of the North Anatolian Shear Zone in Central Pontides (northern Turkey): Insight for geometries and kinematics of deformation structures in a transpressional zone
Ellero, Alessandro; Ottria, Giuseppe; Marroni, Michele; Pandolfi, Luca; Göncüoğlu, Mehmet Cemal (2015-03-01)
The western part of the North Anatolian Shear Zone at the southern boundary of the Central Pontides in Turkey, was investigated in the Kursunlu-Arac area by means of a geological-structural field study. In this area the North Anatolian Shear Zone results in a transpressional deformation zone that extends between two master faults striking parallel to the main shear direction. The main systems of structures identified in the deformation zone appear to be oriented parallel to the directions predicted by Riede...
Citation Formats
A. M. Eker, M. K. Kockar, and H. Akgün, “Evaluation of site effect within the tectonic basin in the northern side of Ankara,” ENGINEERING GEOLOGY, pp. 76–91, 2015, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/35786.