Zülfikar Erhan - Academia.edu (original) (raw)

Papers by Zülfikar Erhan

Fen-mühendislik dergisi/Dokuz Eylül Üniversitesi Mühendislik Fakültesi fen ve mühendislik dergisi, May 14, 2024

TÜBİTAK YDABAG Proje01.10.2005Batı Anadolu'nun kabuk/üst manto yapısını ve anizotropisini dah... more TÜBİTAK YDABAG Proje01.10.2005Batı Anadolu'nun kabuk/üst manto yapısını ve anizotropisini daha iyi anlayabilmek amacıyla, toplam 50 farklı lokasyonda, yaklaşık 11 aylık bir süre ile deprem verisi toplanmıştır. 1-D tomografi uygulaması ile kabuk yapısı ve sismisite, iki farklı receiver fonksiyonu analiz yöntemi ile kabuk kalınlığı ve yapısı, relokasyon ile deprem kümelenmelerinin gözlendiği bölgelerdeki faylanma, moment tensör analizi ile deprem mekanizma çözümleri ve Shear Wave Splitting (SWS) ölçümleri ile üst manto'daki deformasyon ve anizotropi incelenmiştir

EGU General Assembly Conference Abstracts, Apr 1, 2016

GEOPHYSICS, 2012

Geophysical survey techniques have been successfully applied to near-surface cave detection in ka... more Geophysical survey techniques have been successfully applied to near-surface cave detection in karstic terrains. We used magnetic and electrical resistivity surveys to delineate the karstic structure of the Ayvacık Sinkhole, which may be considered to be a vertical cave. The magnetic-total-field-anomaly map helped reveal the metamorphic and sedimentary units in the study area. The total-horizontal-gradient map, which was based on a calculated pseudogravity anomaly, successfully identified the contact between the limestone unit and the cave system. Using these results, we positioned and carried out a vertical electrical sounding (VES) survey with a Schlumberger array along a line that consisted of 11 stations. The VES data were then processed using a 1D global optimization technique, which used a genetic algorithm and a 2D linearized least-squares algorithm. The results were generally in good agreement with each other, and together they pointed out three geologic layers: (1) an overb...

Arabian Journal for Science and Engineering, 2013

The Koçarlı-Demirtepe iron ore deposit area was investigated with geophysical methods (magnetic a... more The Koçarlı-Demirtepe iron ore deposit area was investigated with geophysical methods (magnetic and resistivity) in order to determine the presence of iron deposits, which are important in cement production, in the Koçarlı/Aydın region. The study area is locally known as "iron hill" and iron ore was produced in ancient times from three galleries. In this study, magnetic, vertical electrical sounding (VES) and electrical resistance tomography (ERT) methods were applied to determine the actual geometry and reserves. Magnetic investigations were carried out in order to obtain a general idea about the approximate boundaries of the possible hematite zone. The resulting total magnetic field anomaly map was used to define the boundaries of the hematite zones. The depth of the structure was calculated to be about 27 m with a 2-D inversion method for a dyke model. Three profiles of ERT and five vertical electric soundings were measured in order to define the iron ore geometry. A 2-D inversion method was applied to the multi-electrode data to create an ERT model of the hematite zone geometry and the vertical structural variations. In order to obtain the vertical cross sections of the survey area, a 2-D inversion method was applied to the ERT and VES data. The data sets of vertical electric sounding were combined and modeled as a profile. Results of the 2-D inversion were supported by the ERT model. The depth values obtained from the ERT are in agreement with those from 2-D inversion of magnetic data.

Environmental Geology, 2007

Near-surface geophysical methods are commonly used to solve a wide class of geological, engineeri... more Near-surface geophysical methods are commonly used to solve a wide class of geological, engineering and environmental problems. In this study, a geoelectrical survey was performed to investigate an alluvial aquifer. The study area is located in the southwest of the Ç ubukludag graben, situated in the south of _ Izmir, Turkey. The geophysical studies included the electrical resistivity imaging and self-potential (SP) methods. The resistivity data were acquired along eight profiles in the northern part of the study area by a Wenner-Schlumberger electrode configuration and the data processing was achieved by a tomographic inversion technique. The SP data were collected by gradient technique along 16 profiles. Total field values were calculated for each profile by addition of the successive gradient values, then a total field SP map was obtained. The water-saturated zone in the northern part of the study area was clearly revealed by the electrical resistivity imaging and the SP survey yielded useful information on the subsurface fluid movement.

Journal of Applied Geophysics, 2008

A geophysical survey including electrical resistivity tomography (ERT) and seismic refraction tom... more A geophysical survey including electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) was carried out to study a landslide site in the Altındağ district of İzmir city, western Turkey. In the city, landslide is one of the causes of natural hazard, and one of the most important landslide sites is located in the Altındağ district. The ERT studies were performed along four profiles over the landslide body in the directions of N-S and E-W. A Wenner-Schlumberger configuration was used during the resistivity measurements. The SRT survey was carried out using vertical geophones along a profile coincident with one of N-S trending resistivity profiles. Both the resistivity and the seismic data sets were processed by least-squares inversion techniques. In the first-arrival traveltime inversion of the surface refraction data, a method which is not based on ray tracing was used. Instead, the method used the functional description of traveltimes to generate the Jacobian and this matrix was calculated by using a finite-difference approximation based on the perturbation of the cell slownesses. Traveltime calculations were performed by an eikonal solver. Each technique produced useful results on the internal structure of the landslide, physical properties of the landslide material and sliding surface geometry. The landslide material was characterized by low resistivity and low seismic velocity. The resistivity results also indicated the zones associated with the high water and clay contents within the landslide mass. A layer of consolidated clastic rocks was considered to be the landslide bedrock, and it was represented by relatively high (moderate) resistivity and high velocity. Integrated interpretation of the resistivity and the seismic refraction data along one of N-S trending profiles helped us identify the geometry of the failure surface and the changes in the thickness of the landslide material. An undulating sliding surface is present along that profile and the landslide material gets thicker in the middle and the northern parts (the toe area) of the profile. Moreover, the water content is thought to have a key role in the mass movement in the landslide site.

Bu çalışmanın amacı, İzmir ili Ödemiş ilçesinin Subatan ve Ayvacık Yaylaları arasında yer alan Ay... more Bu çalışmanın amacı, İzmir ili Ödemiş ilçesinin Subatan ve Ayvacık Yaylaları arasında yer alan Ayvacık Düdeni (dikey mağara) civarındaki karstik boşlukların jeofizik yöntemler ile belirlenmesidir. Kireçtaşı-mağara sistemi ile karstik yapı oluşumuna olanak tanımayan örtülü metamorfik birim dokanağı manyetik yöntem ile belirlenerek araştırma alanı sınırlandırılmıştır. Bu alanda, elektrik özdirenç yöntemi, iki farklı doğrultuda ve toplam 17 düşey elektrik sondaj (DES) noktasında Schlumberger elektrot dizilimi ile gerçekleştirilmiştir. DES verilerinin iki-boyutlu (2B) ters çözümünden elde edilen kesitlerden bu alandaki sediman örtünün kalınlığı (~30-50 m) ve yüksek özdirençli olası bir karstik boşluk anomalisi belirlenmiştir. Yakın gelecekte, derin 2B'lu elektrik özdirenç tomografi yönteminin uygulanması ve sonuçlarının karşılaştırılması hedeflenmektedir.

Bu yaz, yüzeye yakın arkeolojik yapıların belirlenmesi amacıyla İzmir'in yaklaşık 60 km güneydoğu... more Bu yaz, yüzeye yakın arkeolojik yapıların belirlenmesi amacıyla İzmir'in yaklaşık 60 km güneydoğusunda ve Efes antik kentinin yaklaşık 10 km kuzeybatısında yer alan Metropolis antik kentinde elektrik özdirenç tomografi, yer radarı ve sismik kırılma tomografi yöntemlerini içeren tümleşik bir arkeojeofizik çalışma gerçekleştirilmiştir. İki-boyutlu (2B) elektrik özdirenç tomografi ölçümleri, GB-KD doğrultulu 11 paralel profilde Wenner elektrot dizilimi ile elde edilmiştir ve değerlendirmede bloklu (L1-normu) ters çözüm yaklaşımı kullanılmıştır. Yer radarı ölçümleri, 500 MHz merkez frekanslı korumalı anten kullanılarak toplanmıştır. Bu çalışmanın sonunda, her üç yöntemden elde edilen sonuçların değerlendirilmesinden sonra, arkeolojik bir yapı olması muhtemel bir belirtinin aydınlatılması için çalışma alanında bir arkeolojik sondaj yapılması önerilmiştir.

Fen-mühendislik dergisi/Dokuz Eylül Üniversitesi Mühendislik Fakültesi fen ve mühendislik dergisi, May 14, 2024

TÜBİTAK YDABAG Proje01.10.2005Batı Anadolu'nun kabuk/üst manto yapısını ve anizotropisini dah... more TÜBİTAK YDABAG Proje01.10.2005Batı Anadolu'nun kabuk/üst manto yapısını ve anizotropisini daha iyi anlayabilmek amacıyla, toplam 50 farklı lokasyonda, yaklaşık 11 aylık bir süre ile deprem verisi toplanmıştır. 1-D tomografi uygulaması ile kabuk yapısı ve sismisite, iki farklı receiver fonksiyonu analiz yöntemi ile kabuk kalınlığı ve yapısı, relokasyon ile deprem kümelenmelerinin gözlendiği bölgelerdeki faylanma, moment tensör analizi ile deprem mekanizma çözümleri ve Shear Wave Splitting (SWS) ölçümleri ile üst manto'daki deformasyon ve anizotropi incelenmiştir

EGU General Assembly Conference Abstracts, Apr 1, 2016

GEOPHYSICS, 2012

Geophysical survey techniques have been successfully applied to near-surface cave detection in ka... more Geophysical survey techniques have been successfully applied to near-surface cave detection in karstic terrains. We used magnetic and electrical resistivity surveys to delineate the karstic structure of the Ayvacık Sinkhole, which may be considered to be a vertical cave. The magnetic-total-field-anomaly map helped reveal the metamorphic and sedimentary units in the study area. The total-horizontal-gradient map, which was based on a calculated pseudogravity anomaly, successfully identified the contact between the limestone unit and the cave system. Using these results, we positioned and carried out a vertical electrical sounding (VES) survey with a Schlumberger array along a line that consisted of 11 stations. The VES data were then processed using a 1D global optimization technique, which used a genetic algorithm and a 2D linearized least-squares algorithm. The results were generally in good agreement with each other, and together they pointed out three geologic layers: (1) an overb...

Arabian Journal for Science and Engineering, 2013

The Koçarlı-Demirtepe iron ore deposit area was investigated with geophysical methods (magnetic a... more The Koçarlı-Demirtepe iron ore deposit area was investigated with geophysical methods (magnetic and resistivity) in order to determine the presence of iron deposits, which are important in cement production, in the Koçarlı/Aydın region. The study area is locally known as "iron hill" and iron ore was produced in ancient times from three galleries. In this study, magnetic, vertical electrical sounding (VES) and electrical resistance tomography (ERT) methods were applied to determine the actual geometry and reserves. Magnetic investigations were carried out in order to obtain a general idea about the approximate boundaries of the possible hematite zone. The resulting total magnetic field anomaly map was used to define the boundaries of the hematite zones. The depth of the structure was calculated to be about 27 m with a 2-D inversion method for a dyke model. Three profiles of ERT and five vertical electric soundings were measured in order to define the iron ore geometry. A 2-D inversion method was applied to the multi-electrode data to create an ERT model of the hematite zone geometry and the vertical structural variations. In order to obtain the vertical cross sections of the survey area, a 2-D inversion method was applied to the ERT and VES data. The data sets of vertical electric sounding were combined and modeled as a profile. Results of the 2-D inversion were supported by the ERT model. The depth values obtained from the ERT are in agreement with those from 2-D inversion of magnetic data.

Environmental Geology, 2007

Near-surface geophysical methods are commonly used to solve a wide class of geological, engineeri... more Near-surface geophysical methods are commonly used to solve a wide class of geological, engineering and environmental problems. In this study, a geoelectrical survey was performed to investigate an alluvial aquifer. The study area is located in the southwest of the Ç ubukludag graben, situated in the south of _ Izmir, Turkey. The geophysical studies included the electrical resistivity imaging and self-potential (SP) methods. The resistivity data were acquired along eight profiles in the northern part of the study area by a Wenner-Schlumberger electrode configuration and the data processing was achieved by a tomographic inversion technique. The SP data were collected by gradient technique along 16 profiles. Total field values were calculated for each profile by addition of the successive gradient values, then a total field SP map was obtained. The water-saturated zone in the northern part of the study area was clearly revealed by the electrical resistivity imaging and the SP survey yielded useful information on the subsurface fluid movement.

Journal of Applied Geophysics, 2008

A geophysical survey including electrical resistivity tomography (ERT) and seismic refraction tom... more A geophysical survey including electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) was carried out to study a landslide site in the Altındağ district of İzmir city, western Turkey. In the city, landslide is one of the causes of natural hazard, and one of the most important landslide sites is located in the Altındağ district. The ERT studies were performed along four profiles over the landslide body in the directions of N-S and E-W. A Wenner-Schlumberger configuration was used during the resistivity measurements. The SRT survey was carried out using vertical geophones along a profile coincident with one of N-S trending resistivity profiles. Both the resistivity and the seismic data sets were processed by least-squares inversion techniques. In the first-arrival traveltime inversion of the surface refraction data, a method which is not based on ray tracing was used. Instead, the method used the functional description of traveltimes to generate the Jacobian and this matrix was calculated by using a finite-difference approximation based on the perturbation of the cell slownesses. Traveltime calculations were performed by an eikonal solver. Each technique produced useful results on the internal structure of the landslide, physical properties of the landslide material and sliding surface geometry. The landslide material was characterized by low resistivity and low seismic velocity. The resistivity results also indicated the zones associated with the high water and clay contents within the landslide mass. A layer of consolidated clastic rocks was considered to be the landslide bedrock, and it was represented by relatively high (moderate) resistivity and high velocity. Integrated interpretation of the resistivity and the seismic refraction data along one of N-S trending profiles helped us identify the geometry of the failure surface and the changes in the thickness of the landslide material. An undulating sliding surface is present along that profile and the landslide material gets thicker in the middle and the northern parts (the toe area) of the profile. Moreover, the water content is thought to have a key role in the mass movement in the landslide site.

Bu çalışmanın amacı, İzmir ili Ödemiş ilçesinin Subatan ve Ayvacık Yaylaları arasında yer alan Ay... more Bu çalışmanın amacı, İzmir ili Ödemiş ilçesinin Subatan ve Ayvacık Yaylaları arasında yer alan Ayvacık Düdeni (dikey mağara) civarındaki karstik boşlukların jeofizik yöntemler ile belirlenmesidir. Kireçtaşı-mağara sistemi ile karstik yapı oluşumuna olanak tanımayan örtülü metamorfik birim dokanağı manyetik yöntem ile belirlenerek araştırma alanı sınırlandırılmıştır. Bu alanda, elektrik özdirenç yöntemi, iki farklı doğrultuda ve toplam 17 düşey elektrik sondaj (DES) noktasında Schlumberger elektrot dizilimi ile gerçekleştirilmiştir. DES verilerinin iki-boyutlu (2B) ters çözümünden elde edilen kesitlerden bu alandaki sediman örtünün kalınlığı (~30-50 m) ve yüksek özdirençli olası bir karstik boşluk anomalisi belirlenmiştir. Yakın gelecekte, derin 2B'lu elektrik özdirenç tomografi yönteminin uygulanması ve sonuçlarının karşılaştırılması hedeflenmektedir.

Bu yaz, yüzeye yakın arkeolojik yapıların belirlenmesi amacıyla İzmir'in yaklaşık 60 km güneydoğu... more Bu yaz, yüzeye yakın arkeolojik yapıların belirlenmesi amacıyla İzmir'in yaklaşık 60 km güneydoğusunda ve Efes antik kentinin yaklaşık 10 km kuzeybatısında yer alan Metropolis antik kentinde elektrik özdirenç tomografi, yer radarı ve sismik kırılma tomografi yöntemlerini içeren tümleşik bir arkeojeofizik çalışma gerçekleştirilmiştir. İki-boyutlu (2B) elektrik özdirenç tomografi ölçümleri, GB-KD doğrultulu 11 paralel profilde Wenner elektrot dizilimi ile elde edilmiştir ve değerlendirmede bloklu (L1-normu) ters çözüm yaklaşımı kullanılmıştır. Yer radarı ölçümleri, 500 MHz merkez frekanslı korumalı anten kullanılarak toplanmıştır. Bu çalışmanın sonunda, her üç yöntemden elde edilen sonuçların değerlendirilmesinden sonra, arkeolojik bir yapı olması muhtemel bir belirtinin aydınlatılması için çalışma alanında bir arkeolojik sondaj yapılması önerilmiştir.