Selda Altuncu Poyraz - Academia.edu (original) (raw)

Papers by Selda Altuncu Poyraz

Applied Sciences

A tsunami warning system providing services in the Eastern Mediterranean, Aegean, Marmara and Bla... more A tsunami warning system providing services in the Eastern Mediterranean, Aegean, Marmara and Black Seas under the UNESCO Intergovernmental Oceanographic Commission (IOC)—Intergovernmental Coordination Group (ICG) for the Tsunami Early Warning and Mitigation System in the North-Eastern Atlantic, the Mediterranean and Connected Seas (NEAMTWS) framework was established in Turkey by the Kandilli Observatory and Earthquake Research Institute (KOERI) (Özel et al., 2011). KOERI’s Regional Earthquake and Tsunami Monitoring Center (RETMC) was established on the foundations of the legacy KOERI National Earthquake Monitoring Center (NEMC) by adding observation, analysis and operational capability related to tsunami early warnings after an extensive preparatory period during 2009 and 2011. The center initiated its test-mode 7/24 operational status as a national tsunami warning center in 2011, and after a one year period it became operational as a candidate tsunami warning center for NEAMTWS on...

Shear wave splitting measurements across the North Anatolian Fault (NAF) in Northern Turkey are c... more Shear wave splitting measurements across the North Anatolian Fault (NAF) in Northern Turkey are calculated from teleseismic SKS arrivals recorded by the dense temporary DANA seismological array to ...

Son defa 1912 yilinda, magnitutu 7.3 (Ms) olan bir depremle hareket eden Ganos Fayi; K70°D dogrul... more Son defa 1912 yilinda, magnitutu 7.3 (Ms) olan bir depremle hareket eden Ganos Fayi; K70°D dogrultulu sag yanal dogrultu atimli bir fay olarak, Gazikoy (Tekirdag) ile Saros Korfezi arasinda uzanmaktadir. Bu calismada; Ganos Fayi boyunca fay topluluklarinin kinematik analizi, depremlerin odak mekanizmasi ters cozumleri ve uydu goruntuleri uzerinde uzaktan algilama calismalariyla; Ganos Fayi ve bolgedeki Gec Senozoyik yasli gerilme durumlari belirlenmistir. Fay boyunca birbirleriyle uyumlu faylanma mekanizmalariyla bir ana tektonik rejimin varligi saptanmistir. Bu faylanmalardan ilki, KB-GD yonlu sikisma ve KD-GB yonlu acilma ekseni ile karakterize olan dogrultu atimli faylanmadir. En buyuk asal gerilme ekseni (σ 1) 130°±16° ve en kucuk asal gerilme ekseni (σ3 ) 53°±13° olarak belirlenmis ve Rm orani 0.49 olarak hesaplanmistir. Bu faylanma ile uyumlu, es zamanli ve KD-GB dogrultulu acilma ekseni ile temsil edilen (σ 1) dusey yondedir) lokal normal faylanmalar da belirlenmist...

ABSTRACT The Isparta Angle is a prominent tectonic feature in Eastern Mediterranean region lying ... more ABSTRACT The Isparta Angle is a prominent tectonic feature in Eastern Mediterranean region lying to the north of Africa-Anatolia collision zone and to the east of Aegean extensional zone. ISP and AKSU seismic stations are located in this area. In order to model the crustal structure beneath the ISP and AKSU seismic stations the receiver function and surface wave group velocity joint inversion method were applied. Well described 32 earthquakes selected from 205 eartquakes recorded by broand-band ISP seismic station in the year between 2005-2008 and 45 earthquakes selected from 117 earthquakes recorded by AKSU seismograph station were solved by using receiver function and surface wave group velocity joint inversion method. It was found that the crustal thickness under ISP station was approximately 31-35 km and under the AKSU station was approximately 33-36km. The very low shear wave velocity for ISP and AKSU station found by receiver function technique could be related to shallow asthenospheric mantle. Using the two crustal structures derived from Receiver function method we calculated mechanism of 21 Egirdir earthquakes with magnitudes between 3.5>M>5.0 using regional moment tensor inversion technique. The Egirdir local earthqukes of 2007 took place on a fault plane striking NW-SE showing normal faulting with strike slip component mechanism which we infer as a fault plane considering the epicentral distribution of the seismic activity. The event distribution show that these earthquakes did not take part on the well-know NNE-SSW trending Egirdir fault but rather they were either on the Egirdir conjuction fault or on the fault that is the extension of the Aksu fault that have NW-SE strike.

Focal Mechanism Solutions and Soil-Structure Interactionn Features of Hakkari-Sutluce Earthquake... more Focal Mechanism Solutions and Soil-Structure Interactionn Features of Hakkari-Sutluce Earthquake, January 25, 2005

2005 yilindan beri Kandilli Rasathanesi ve Deprem Arastirma Ensititusu (KRDAE), Bolgesel Deprem-T... more 2005 yilindan beri Kandilli Rasathanesi ve Deprem Arastirma Ensititusu (KRDAE), Bolgesel Deprem-Tsunami Izleme ve Degerlendirme Merkezi (BDTIM) Turkiye ve civarinda meydana gelen buyuklugu M≥4.5 olan depremler icin kaynak parametrelerini belirlemekte ve cozumlerini arastirmacilar icin paylasmaktadir. Bu calismada da buyuklugu M≥4.2 olan 146 deprem icin (2016-2019) BDTIM ve Basbakanlik Icisleri Bakanligi Afet ve Acil Durum Yonetimi Baskanligi Deprem Dairesi (AFAD)’ne ait yakin-alan ve bolgesel dalga sekilleri kullanilarak kaynak parametreleri bulunmustur. KDRAE-BDTIM tarafindan olusturulan moment tensor katalogunun arastirmacilar icin guvenilir bir kaynak olacagi dusunulmektedir. Ayrica 2016-2019 yillari arasinda meydana gelen ulkemiz icin onem teskil edecek 3 onemli depremin (Ayvacik-Canakkale 2017, Gokova 2017 ve Ege Denizi 2017) depremselligi de calisma kapsaminda irdelenmistir.

ABSTRACT The North Anatolian Fault Zone (NAFZ) is a major continental strike-slip fault system, s... more ABSTRACT The North Anatolian Fault Zone (NAFZ) is a major continental strike-slip fault system, similar in size and scale to the San Andreas system, that extends ~1200 km across Turkey from the Aegean coast on the west to the Lake Van region in the east. FaultLab is a multidisciplinary project that aims to better understand deformation throughout the entire crust in the NAFZ, in particular the expected transition from narrow zones of brittle deformation in the upper crust to broad shear zones in the lower crust/upper mantle and how these features contribute to the earthquake loading cycle. The project incorporates broadband seismology, satellite geodesy, structural geology and numerical modelling in order to give an unprecedented view of the dynamic state of the NAFZ in the vicinity of the devastating 1999 Izmit and Düzce earthquakes. This contribution will discuss the first results from the seismic component of the project, a 73 station network encompassing the northern and southern branches of the NAFZ in the Sakarya region. Deployed in May 2012, the Dense Array for North Anatolia (DANA) is arranged as a 6×11 grid with a nominal station spacing of 7 km, with a further 7 stations located outside of the grid. Receiver function analysis will provide estimates of bulk crustal properties, along with information regarding heterogeneity at depth (dipping interfaces/anisotropy). With the excellent resolution afforded by the DANA network, we will present results using the technique of teleseismic scattering tomography. The method uses a full waveform inversion of teleseismic signals coupled with array processing techniques to infer the properties and location of small-scale heterogeneities (with scales on the order of the seismic wavelength) within the crust. Images obtained using these methods will provide evidence for how the deformation is distributed within the fault zone at depth, providing constraints that can be used in conjunction with structural analyses of exhumed fault segments elsewhere, and models of geodetic strain-rate across the fault system. By linking together results from the complementary techniques being employed in the FaultLab project, we aim to produce a comprehensive picture of fault structure and dynamics throughout the crust and shallow upper mantle of this major active fault zone.

As the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes i... more As the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes in the region, the Kandilli Observatory and Earthquake Research Institute (KOERI) has a long history in seismic observation, which dates back to the installation of its first seismometers soon after the devastating Istanbul earthquake of 10 July 1894. For over a century, since the deployment of its first seismometer, the KOERI seismic network has grown steadily in time. In this article, we present the KOERI seismic network facilities as a data center for the seismological community, providing data and services through the European Integrated Data Archive (EIDA) and the Rapid Raw Strong-Motion (RRSM) database, both integrated in the Observatories and Research Facilities for European Seismology (ORFEUS). The objective of this article is to provide an overview of the KOERI seismic services within ORFEUS and to introduce some of the procedures that allow to check the health of the seismic net...

Turkiye ve cevresi genc ve aktif bir tektonik kusak uzerinde yer almaktadir. Devam eden surekli v... more Turkiye ve cevresi genc ve aktif bir tektonik kusak uzerinde yer almaktadir. Devam eden surekli ve yogun deformasyon sonucu bolgede farkli topografik, kabuk ve orojenik ozellikler gozlenmektedir. Turkiye’nin sismotektonik yapisinin daha detayli calisilabilmesi, can ve mal kaybina neden olabilecek depremlerin ozelliklerinin daha iyi anlasilabilmesi icin bolgenin sismotektonik ozelliklerini ortaya koyan detayli veri tabaninin bir butun olarak olusturulmasi onem kazanmaktadir. Cografi bilgi sistemleri (CBS) kullanilarak Turkiye ve civarinda meydana gelen depremlerin lokasyonlari, depremlere ait mekanizma cozumleri, bolgedeki tarihsel depremler, deprem kayit cihazlari dagilimi gibi verilerin butunlestirilmesi ile dogru ve guvenilir bilgiye hizli ulasim mumkun olmaktadir. Bu calismada Ulusal Deprem Izleme Merkezi’nde (UDIM) kullanilan verilerin (istasyon ozellikleri, deprem lokasyonlari, fay duzlemi cozumleri, tarihsel depremler) Cografi Bilgi Sistemlerine (CBS) aktarilmasi ile bir veri ...

ABSTRACT North Anatolian Fault (NAF) is one of the major strike slip fault systems on earth compa... more ABSTRACT North Anatolian Fault (NAF) is one of the major strike slip fault systems on earth comparable to San Andreas Fault some ways. Devastating earthquakes have occurred along this system causing major damage and casualties. In order to comprehensively investigate the shallow and deep crustal structure beneath the western segment of North Anatolian Fault (NAF), a temporary dense seismic network consisting of 73 broadband sensors was deployed in early May 2012 with support from The Natural Environment Research Council (NERC) and partial support from Bogazci University Research Fund. This joint project involves researchers from University of Leeds, UK and Bogazici University, Kandilli Observatory and Earthquake Research Institute (KOERI). In addition to the 63 sensors provided by SEIS-UK instrument pool and three permanent KOERI sites in the region, another seven stations of KOERI-Department of Geophysics were installed surrounding the rectangular grid with the aim of further enhancing the detection capability of this dense seismic array (map). Six months of seismic data have been collected and initial analysis underway. This research focuses on upper crustal studies such as earthquake locations (especially micro-seismic activity), moment tensor inversions and ambient noise correlations. Accurate earthquake locations will eventually lead to high resolution seismic images of NAF including both the northern and the southern branches in the upper crust. In order to put additional constraints on the active tectonics of the western part of NAF, we determined fault plane solutions using Regional Moment Tensor Inversion (RMT) and P wave first motion method. For the analysis of high quality fault plane solutions, data from KOERI and the DANA project were merged. Furthermore, detailed Moho topography will be revealed via receiver function method. Iterative time domain deconvolution was used to obtain receiver functions and H-K stacking was applied to calculate crustal thickness values. The preliminary results indicate that Moho is located at roughly 26 - 28 km depth with Vp/Vs ratios higher than 1.98. We also present the observed Moho depth variations along N-S and E-W profiles beneath the western segment of NAF.

Journal of Asian Earth Sciences

Abstract The west to southwestward motion of the Anatolian block results from the relative motion... more Abstract The west to southwestward motion of the Anatolian block results from the relative motions between the Eurasian, Arabian and African plates along the right-lateral North Anatolian Fault Zone in the north and left-lateral East Anatolian Fault Zone in the east. The Biga Peninsula is tectonically influenced by the Anatolian motion originating along the North Anatolian Fault Zone which splits into two main (northern and southern) branches in the east of Marmara region: the southern branch extends towards the Biga Peninsula which is characterized by strike-slip to oblique normal faulting stress regime in the central to northern part. The southernmost part of peninsula is characterized by a normal to oblique faulting stress regime. The analysis of both seismological and structural field data confirms the change of stress regime from strike-slip character in the center and north to normal faulting character in the south of peninsula where the earthquake swarm recently occurred. The earthquakes began on 14 January 2017 (Mw: 4.4) on Tuzla Fault and migrated southward along the Kocakoy and Babakale's stepped-normal faults of over three months. The inversion of focal mechanisms yields a normal faulting stress regime with an approximately N-S (N4°E) σ3 axis. The inversion of earthquakes occurring in central and northern Biga Peninsula and the north Aegean region gives a strike-slip stress regime with approximately WNW-ESE (N85°W) σ1 and NNE-SSW (N17°E) σ3 axis. The strike-slip stress regime is attributed to westward Anatolian motion, while the normal faulting stress regime is attributed to both the extrusion of Anatolian block and the slab-pull force of the subducting African plate along the Hellenic arc.

Journal of Asian Earth Sciences

Abstract Eastern Anatolia is a ∼2 km high plateau shaped by the continent-continent collision of ... more Abstract Eastern Anatolia is a ∼2 km high plateau shaped by the continent-continent collision of the Arabian and Eurasian plates. The left lateral East Anatolian Fault Zone, the right lateral North Anatolian Fault Zone and the Bitlis fold-thrust belt are the major tectonic boundaries of this convergence zone. The Arabian-Eurasian collision has resulted in high volcanism and well recorded seismic activity in Eastern Anatolia and its surroundings. Karliova Junction is located at the intersection of these major fault systems and contains secondary faults such as the Karakocan fault and the Sancak-Uzunpinar fault. We processed high quality waveform data collected from a recent seismic activity in the proximity of the city of Bingol where the largest event is the moderate-size earthquake (Mw = 5.3) occurred on 2 December 2015. This event is located to the west of Karliova Junction and to the northwest of Sancak-Uzunpinar fault. The spatial distribution of the aftershocks points out unmapped faults with NNW-SSE alignment towards the west of Sancak-Uzunpinar fault. Aftershock depth distribution indicates a nearly 15 km deep brittle seismogenic zone. The relocated aftershock distributions and seismic moment calculations yield a rupture area 9 km in length and 5 km in width with an average 8 cm of slip. The latest four earthquakes preceding the 2015 Eq with magnitudes larger than Mw > 6 enhanced the Coulomb stress failure in the 2015 Bingol Earthquake rupture area. The ruptured fault plane is in-line with the optimally oriented right-lateral strike-slip faults.

Earth and Planetary Science Letters, 2015

Continental scale deformation is often localized along strike-slip faults constituting considerab... more Continental scale deformation is often localized along strike-slip faults constituting considerable 18 seismic hazard in many locations. Nonetheless, the depth extent and precise geometry of such Major continental strike-slip faults, such as the North Anatolian fault Zone (NAFZ) in Turkey or the 44 San Andreas Fault in the USA, are key elements in our understanding of plate tectonics. Such 45 faults are clearly defined at the surface but considerable uncertainty surrounds their structure in 46 the mid to lower crust and upper mantle, and specifically how deformation is focussed in shear 47 zones that are presumed to extend beneath seismically active fault planes (e.g., Handy et al., 2007; 48 Platt and Behr, 2011). An understanding of such fault systems (e.g., Pollitz et al., 2001) requires 49 characterisation of the structure and physical properties of the crust and upper mantle to 50 constrain the rheological parameters that determine how stress is redistributed during the 51 earthquake cycle (e.g., Hearn et al., 2009). Localized zones of relatively high or low viscosity can 52 have an important impact on this cycle (Yamasaki et al., 2014). 53 Modelling of geodetic deformation has provided some constraints on the physical variation of 54

Tectonophysics, 2015

With the aim of extensively investigating the crustal structure beneath the western segment of th... more With the aim of extensively investigating the crustal structure beneath the western segment of the North Anatolian Fault Zone where it splays into northern and southern branches, a temporary seismic network (Dense array for North Anatolia-DANA) consisting of 70 stations was deployed in early May 2012 and operated for 18 months in the Sakarya region during the FaultLab experiment. Out of 2437 events contaminated by explosions, we extracted 1371 well located earthquakes. The enhanced station coverage having a nominal station spacing of 7 km, lead to a minimum magnitude calculation of 0.1. Horizontal and vertical location uncertainties within the array do not exceed 0.8 km and 0.9 km, respectively. We observe considerable seismic activity along both branches of the fault where the depth of the seismogenic zone was mostly confined to 15 km. Using our current earthquake catalogue we obtained a b-value of 1. We also mapped the b-value variation with depth and observed a gradual decrease. Furthermore, we determined the source parameters of 41 earthquakes with magnitudes greater than 1.8 using P-wave first motion polarity method. Regional Moment Tensor Inversion method was also applied to earthquakes with magnitudes greater than 3.0. Focal mechanism solutions confirm that Sakarya and its vicinity is stressed by a compressional regime showing a primarily oblique-slip motion character. Stress tensor analysis indicates that the maximum principal stress is aligned in WNW-ESE direction and the tensional axis is aligned in NNE-SSW direction.

Malatya-Elazıg-Bingöl-Diyarbakır-Adıyaman bölgesinin kabuk yapısını ortaya koymak için bölgenin g... more Malatya-Elazıg-Bingöl-Diyarbakır-Adıyaman bölgesinin kabuk yapısını ortaya koymak için bölgenin gravite ve havadan manyetik verileri analiz edilmistir. Gravite ve manyetik verilere Yapı Sınır Analizi (YSA) teknigi uygulanarak anomali yapılarının uzanım ve sınırları arastırılmıs ve çalısma alanına ait jeolojik bilgiler ile karsılastırılmıstır. Elde edilen sayısal sınırlar bölgedeki kıtasal bloklar ve yapısal trendler olan Bitlis-Pötürge Sütur Zonu (BPSZ) ve Dogu Anadolu Fay Zonu (DAFZ) ile uyum göstermektedir. Anomalilere neden olan kaynak derinliklerinin arastırılması için spektral analiz tekniklerinden güç spektrumu yönteminden yararlanılmıstır. Çalısma alanında ortalama kabuk derinligi 44 km olarak bulunmustur. Gravite verilerden GD-KB yönünde alınan kesit degerleri degerlendirilerek Talwani modelleme teknigine göre iki boyutlu bir kabuk modeli olusturulmustur. Buna göre çalısma alanında kabuk kalınlıgı güneyden kuzeye dogru 38 km ile 51 km arasında degisim göstermektedir. DAFZ’ni...

Geophysical Research Letters, 2015

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Proceedings, 2013

ABSTRACT This study focuses on upper crustal studies such as earthquake locations (especially mic... more ABSTRACT This study focuses on upper crustal studies such as earthquake locations (especially micro-seismic activity), moment tensor inversions and receiver function analysis. Accurate earthquake locations will eventually lead to high-resolution seismic images of NAF including both the northern and the southern branches in the upper crust.In this study, 722 earthquakes within the time period of 09 May – 17 September 2012 were located. Furthermore, the crustal structure beneath the DANA Array is investigated using receiver functions obtained from the teleseismic recordings from a total of 73 broadband stations. Calculated Moho depth beneath the most of stations is between 33 and 36 km.

Applied Sciences

A tsunami warning system providing services in the Eastern Mediterranean, Aegean, Marmara and Bla... more A tsunami warning system providing services in the Eastern Mediterranean, Aegean, Marmara and Black Seas under the UNESCO Intergovernmental Oceanographic Commission (IOC)—Intergovernmental Coordination Group (ICG) for the Tsunami Early Warning and Mitigation System in the North-Eastern Atlantic, the Mediterranean and Connected Seas (NEAMTWS) framework was established in Turkey by the Kandilli Observatory and Earthquake Research Institute (KOERI) (Özel et al., 2011). KOERI’s Regional Earthquake and Tsunami Monitoring Center (RETMC) was established on the foundations of the legacy KOERI National Earthquake Monitoring Center (NEMC) by adding observation, analysis and operational capability related to tsunami early warnings after an extensive preparatory period during 2009 and 2011. The center initiated its test-mode 7/24 operational status as a national tsunami warning center in 2011, and after a one year period it became operational as a candidate tsunami warning center for NEAMTWS on...

Shear wave splitting measurements across the North Anatolian Fault (NAF) in Northern Turkey are c... more Shear wave splitting measurements across the North Anatolian Fault (NAF) in Northern Turkey are calculated from teleseismic SKS arrivals recorded by the dense temporary DANA seismological array to ...

Son defa 1912 yilinda, magnitutu 7.3 (Ms) olan bir depremle hareket eden Ganos Fayi; K70°D dogrul... more Son defa 1912 yilinda, magnitutu 7.3 (Ms) olan bir depremle hareket eden Ganos Fayi; K70°D dogrultulu sag yanal dogrultu atimli bir fay olarak, Gazikoy (Tekirdag) ile Saros Korfezi arasinda uzanmaktadir. Bu calismada; Ganos Fayi boyunca fay topluluklarinin kinematik analizi, depremlerin odak mekanizmasi ters cozumleri ve uydu goruntuleri uzerinde uzaktan algilama calismalariyla; Ganos Fayi ve bolgedeki Gec Senozoyik yasli gerilme durumlari belirlenmistir. Fay boyunca birbirleriyle uyumlu faylanma mekanizmalariyla bir ana tektonik rejimin varligi saptanmistir. Bu faylanmalardan ilki, KB-GD yonlu sikisma ve KD-GB yonlu acilma ekseni ile karakterize olan dogrultu atimli faylanmadir. En buyuk asal gerilme ekseni (σ 1) 130°±16° ve en kucuk asal gerilme ekseni (σ3 ) 53°±13° olarak belirlenmis ve Rm orani 0.49 olarak hesaplanmistir. Bu faylanma ile uyumlu, es zamanli ve KD-GB dogrultulu acilma ekseni ile temsil edilen (σ 1) dusey yondedir) lokal normal faylanmalar da belirlenmist...

ABSTRACT The Isparta Angle is a prominent tectonic feature in Eastern Mediterranean region lying ... more ABSTRACT The Isparta Angle is a prominent tectonic feature in Eastern Mediterranean region lying to the north of Africa-Anatolia collision zone and to the east of Aegean extensional zone. ISP and AKSU seismic stations are located in this area. In order to model the crustal structure beneath the ISP and AKSU seismic stations the receiver function and surface wave group velocity joint inversion method were applied. Well described 32 earthquakes selected from 205 eartquakes recorded by broand-band ISP seismic station in the year between 2005-2008 and 45 earthquakes selected from 117 earthquakes recorded by AKSU seismograph station were solved by using receiver function and surface wave group velocity joint inversion method. It was found that the crustal thickness under ISP station was approximately 31-35 km and under the AKSU station was approximately 33-36km. The very low shear wave velocity for ISP and AKSU station found by receiver function technique could be related to shallow asthenospheric mantle. Using the two crustal structures derived from Receiver function method we calculated mechanism of 21 Egirdir earthquakes with magnitudes between 3.5>M>5.0 using regional moment tensor inversion technique. The Egirdir local earthqukes of 2007 took place on a fault plane striking NW-SE showing normal faulting with strike slip component mechanism which we infer as a fault plane considering the epicentral distribution of the seismic activity. The event distribution show that these earthquakes did not take part on the well-know NNE-SSW trending Egirdir fault but rather they were either on the Egirdir conjuction fault or on the fault that is the extension of the Aksu fault that have NW-SE strike.

Focal Mechanism Solutions and Soil-Structure Interactionn Features of Hakkari-Sutluce Earthquake... more Focal Mechanism Solutions and Soil-Structure Interactionn Features of Hakkari-Sutluce Earthquake, January 25, 2005

2005 yilindan beri Kandilli Rasathanesi ve Deprem Arastirma Ensititusu (KRDAE), Bolgesel Deprem-T... more 2005 yilindan beri Kandilli Rasathanesi ve Deprem Arastirma Ensititusu (KRDAE), Bolgesel Deprem-Tsunami Izleme ve Degerlendirme Merkezi (BDTIM) Turkiye ve civarinda meydana gelen buyuklugu M≥4.5 olan depremler icin kaynak parametrelerini belirlemekte ve cozumlerini arastirmacilar icin paylasmaktadir. Bu calismada da buyuklugu M≥4.2 olan 146 deprem icin (2016-2019) BDTIM ve Basbakanlik Icisleri Bakanligi Afet ve Acil Durum Yonetimi Baskanligi Deprem Dairesi (AFAD)’ne ait yakin-alan ve bolgesel dalga sekilleri kullanilarak kaynak parametreleri bulunmustur. KDRAE-BDTIM tarafindan olusturulan moment tensor katalogunun arastirmacilar icin guvenilir bir kaynak olacagi dusunulmektedir. Ayrica 2016-2019 yillari arasinda meydana gelen ulkemiz icin onem teskil edecek 3 onemli depremin (Ayvacik-Canakkale 2017, Gokova 2017 ve Ege Denizi 2017) depremselligi de calisma kapsaminda irdelenmistir.

ABSTRACT The North Anatolian Fault Zone (NAFZ) is a major continental strike-slip fault system, s... more ABSTRACT The North Anatolian Fault Zone (NAFZ) is a major continental strike-slip fault system, similar in size and scale to the San Andreas system, that extends ~1200 km across Turkey from the Aegean coast on the west to the Lake Van region in the east. FaultLab is a multidisciplinary project that aims to better understand deformation throughout the entire crust in the NAFZ, in particular the expected transition from narrow zones of brittle deformation in the upper crust to broad shear zones in the lower crust/upper mantle and how these features contribute to the earthquake loading cycle. The project incorporates broadband seismology, satellite geodesy, structural geology and numerical modelling in order to give an unprecedented view of the dynamic state of the NAFZ in the vicinity of the devastating 1999 Izmit and Düzce earthquakes. This contribution will discuss the first results from the seismic component of the project, a 73 station network encompassing the northern and southern branches of the NAFZ in the Sakarya region. Deployed in May 2012, the Dense Array for North Anatolia (DANA) is arranged as a 6×11 grid with a nominal station spacing of 7 km, with a further 7 stations located outside of the grid. Receiver function analysis will provide estimates of bulk crustal properties, along with information regarding heterogeneity at depth (dipping interfaces/anisotropy). With the excellent resolution afforded by the DANA network, we will present results using the technique of teleseismic scattering tomography. The method uses a full waveform inversion of teleseismic signals coupled with array processing techniques to infer the properties and location of small-scale heterogeneities (with scales on the order of the seismic wavelength) within the crust. Images obtained using these methods will provide evidence for how the deformation is distributed within the fault zone at depth, providing constraints that can be used in conjunction with structural analyses of exhumed fault segments elsewhere, and models of geodetic strain-rate across the fault system. By linking together results from the complementary techniques being employed in the FaultLab project, we aim to produce a comprehensive picture of fault structure and dynamics throughout the crust and shallow upper mantle of this major active fault zone.

As the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes i... more As the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes in the region, the Kandilli Observatory and Earthquake Research Institute (KOERI) has a long history in seismic observation, which dates back to the installation of its first seismometers soon after the devastating Istanbul earthquake of 10 July 1894. For over a century, since the deployment of its first seismometer, the KOERI seismic network has grown steadily in time. In this article, we present the KOERI seismic network facilities as a data center for the seismological community, providing data and services through the European Integrated Data Archive (EIDA) and the Rapid Raw Strong-Motion (RRSM) database, both integrated in the Observatories and Research Facilities for European Seismology (ORFEUS). The objective of this article is to provide an overview of the KOERI seismic services within ORFEUS and to introduce some of the procedures that allow to check the health of the seismic net...

Turkiye ve cevresi genc ve aktif bir tektonik kusak uzerinde yer almaktadir. Devam eden surekli v... more Turkiye ve cevresi genc ve aktif bir tektonik kusak uzerinde yer almaktadir. Devam eden surekli ve yogun deformasyon sonucu bolgede farkli topografik, kabuk ve orojenik ozellikler gozlenmektedir. Turkiye’nin sismotektonik yapisinin daha detayli calisilabilmesi, can ve mal kaybina neden olabilecek depremlerin ozelliklerinin daha iyi anlasilabilmesi icin bolgenin sismotektonik ozelliklerini ortaya koyan detayli veri tabaninin bir butun olarak olusturulmasi onem kazanmaktadir. Cografi bilgi sistemleri (CBS) kullanilarak Turkiye ve civarinda meydana gelen depremlerin lokasyonlari, depremlere ait mekanizma cozumleri, bolgedeki tarihsel depremler, deprem kayit cihazlari dagilimi gibi verilerin butunlestirilmesi ile dogru ve guvenilir bilgiye hizli ulasim mumkun olmaktadir. Bu calismada Ulusal Deprem Izleme Merkezi’nde (UDIM) kullanilan verilerin (istasyon ozellikleri, deprem lokasyonlari, fay duzlemi cozumleri, tarihsel depremler) Cografi Bilgi Sistemlerine (CBS) aktarilmasi ile bir veri ...

ABSTRACT North Anatolian Fault (NAF) is one of the major strike slip fault systems on earth compa... more ABSTRACT North Anatolian Fault (NAF) is one of the major strike slip fault systems on earth comparable to San Andreas Fault some ways. Devastating earthquakes have occurred along this system causing major damage and casualties. In order to comprehensively investigate the shallow and deep crustal structure beneath the western segment of North Anatolian Fault (NAF), a temporary dense seismic network consisting of 73 broadband sensors was deployed in early May 2012 with support from The Natural Environment Research Council (NERC) and partial support from Bogazci University Research Fund. This joint project involves researchers from University of Leeds, UK and Bogazici University, Kandilli Observatory and Earthquake Research Institute (KOERI). In addition to the 63 sensors provided by SEIS-UK instrument pool and three permanent KOERI sites in the region, another seven stations of KOERI-Department of Geophysics were installed surrounding the rectangular grid with the aim of further enhancing the detection capability of this dense seismic array (map). Six months of seismic data have been collected and initial analysis underway. This research focuses on upper crustal studies such as earthquake locations (especially micro-seismic activity), moment tensor inversions and ambient noise correlations. Accurate earthquake locations will eventually lead to high resolution seismic images of NAF including both the northern and the southern branches in the upper crust. In order to put additional constraints on the active tectonics of the western part of NAF, we determined fault plane solutions using Regional Moment Tensor Inversion (RMT) and P wave first motion method. For the analysis of high quality fault plane solutions, data from KOERI and the DANA project were merged. Furthermore, detailed Moho topography will be revealed via receiver function method. Iterative time domain deconvolution was used to obtain receiver functions and H-K stacking was applied to calculate crustal thickness values. The preliminary results indicate that Moho is located at roughly 26 - 28 km depth with Vp/Vs ratios higher than 1.98. We also present the observed Moho depth variations along N-S and E-W profiles beneath the western segment of NAF.

Journal of Asian Earth Sciences

Abstract The west to southwestward motion of the Anatolian block results from the relative motion... more Abstract The west to southwestward motion of the Anatolian block results from the relative motions between the Eurasian, Arabian and African plates along the right-lateral North Anatolian Fault Zone in the north and left-lateral East Anatolian Fault Zone in the east. The Biga Peninsula is tectonically influenced by the Anatolian motion originating along the North Anatolian Fault Zone which splits into two main (northern and southern) branches in the east of Marmara region: the southern branch extends towards the Biga Peninsula which is characterized by strike-slip to oblique normal faulting stress regime in the central to northern part. The southernmost part of peninsula is characterized by a normal to oblique faulting stress regime. The analysis of both seismological and structural field data confirms the change of stress regime from strike-slip character in the center and north to normal faulting character in the south of peninsula where the earthquake swarm recently occurred. The earthquakes began on 14 January 2017 (Mw: 4.4) on Tuzla Fault and migrated southward along the Kocakoy and Babakale's stepped-normal faults of over three months. The inversion of focal mechanisms yields a normal faulting stress regime with an approximately N-S (N4°E) σ3 axis. The inversion of earthquakes occurring in central and northern Biga Peninsula and the north Aegean region gives a strike-slip stress regime with approximately WNW-ESE (N85°W) σ1 and NNE-SSW (N17°E) σ3 axis. The strike-slip stress regime is attributed to westward Anatolian motion, while the normal faulting stress regime is attributed to both the extrusion of Anatolian block and the slab-pull force of the subducting African plate along the Hellenic arc.

Journal of Asian Earth Sciences

Abstract Eastern Anatolia is a ∼2 km high plateau shaped by the continent-continent collision of ... more Abstract Eastern Anatolia is a ∼2 km high plateau shaped by the continent-continent collision of the Arabian and Eurasian plates. The left lateral East Anatolian Fault Zone, the right lateral North Anatolian Fault Zone and the Bitlis fold-thrust belt are the major tectonic boundaries of this convergence zone. The Arabian-Eurasian collision has resulted in high volcanism and well recorded seismic activity in Eastern Anatolia and its surroundings. Karliova Junction is located at the intersection of these major fault systems and contains secondary faults such as the Karakocan fault and the Sancak-Uzunpinar fault. We processed high quality waveform data collected from a recent seismic activity in the proximity of the city of Bingol where the largest event is the moderate-size earthquake (Mw = 5.3) occurred on 2 December 2015. This event is located to the west of Karliova Junction and to the northwest of Sancak-Uzunpinar fault. The spatial distribution of the aftershocks points out unmapped faults with NNW-SSE alignment towards the west of Sancak-Uzunpinar fault. Aftershock depth distribution indicates a nearly 15 km deep brittle seismogenic zone. The relocated aftershock distributions and seismic moment calculations yield a rupture area 9 km in length and 5 km in width with an average 8 cm of slip. The latest four earthquakes preceding the 2015 Eq with magnitudes larger than Mw > 6 enhanced the Coulomb stress failure in the 2015 Bingol Earthquake rupture area. The ruptured fault plane is in-line with the optimally oriented right-lateral strike-slip faults.

Earth and Planetary Science Letters, 2015

Continental scale deformation is often localized along strike-slip faults constituting considerab... more Continental scale deformation is often localized along strike-slip faults constituting considerable 18 seismic hazard in many locations. Nonetheless, the depth extent and precise geometry of such Major continental strike-slip faults, such as the North Anatolian fault Zone (NAFZ) in Turkey or the 44 San Andreas Fault in the USA, are key elements in our understanding of plate tectonics. Such 45 faults are clearly defined at the surface but considerable uncertainty surrounds their structure in 46 the mid to lower crust and upper mantle, and specifically how deformation is focussed in shear 47 zones that are presumed to extend beneath seismically active fault planes (e.g., Handy et al., 2007; 48 Platt and Behr, 2011). An understanding of such fault systems (e.g., Pollitz et al., 2001) requires 49 characterisation of the structure and physical properties of the crust and upper mantle to 50 constrain the rheological parameters that determine how stress is redistributed during the 51 earthquake cycle (e.g., Hearn et al., 2009). Localized zones of relatively high or low viscosity can 52 have an important impact on this cycle (Yamasaki et al., 2014). 53 Modelling of geodetic deformation has provided some constraints on the physical variation of 54

Tectonophysics, 2015

With the aim of extensively investigating the crustal structure beneath the western segment of th... more With the aim of extensively investigating the crustal structure beneath the western segment of the North Anatolian Fault Zone where it splays into northern and southern branches, a temporary seismic network (Dense array for North Anatolia-DANA) consisting of 70 stations was deployed in early May 2012 and operated for 18 months in the Sakarya region during the FaultLab experiment. Out of 2437 events contaminated by explosions, we extracted 1371 well located earthquakes. The enhanced station coverage having a nominal station spacing of 7 km, lead to a minimum magnitude calculation of 0.1. Horizontal and vertical location uncertainties within the array do not exceed 0.8 km and 0.9 km, respectively. We observe considerable seismic activity along both branches of the fault where the depth of the seismogenic zone was mostly confined to 15 km. Using our current earthquake catalogue we obtained a b-value of 1. We also mapped the b-value variation with depth and observed a gradual decrease. Furthermore, we determined the source parameters of 41 earthquakes with magnitudes greater than 1.8 using P-wave first motion polarity method. Regional Moment Tensor Inversion method was also applied to earthquakes with magnitudes greater than 3.0. Focal mechanism solutions confirm that Sakarya and its vicinity is stressed by a compressional regime showing a primarily oblique-slip motion character. Stress tensor analysis indicates that the maximum principal stress is aligned in WNW-ESE direction and the tensional axis is aligned in NNE-SSW direction.

Malatya-Elazıg-Bingöl-Diyarbakır-Adıyaman bölgesinin kabuk yapısını ortaya koymak için bölgenin g... more Malatya-Elazıg-Bingöl-Diyarbakır-Adıyaman bölgesinin kabuk yapısını ortaya koymak için bölgenin gravite ve havadan manyetik verileri analiz edilmistir. Gravite ve manyetik verilere Yapı Sınır Analizi (YSA) teknigi uygulanarak anomali yapılarının uzanım ve sınırları arastırılmıs ve çalısma alanına ait jeolojik bilgiler ile karsılastırılmıstır. Elde edilen sayısal sınırlar bölgedeki kıtasal bloklar ve yapısal trendler olan Bitlis-Pötürge Sütur Zonu (BPSZ) ve Dogu Anadolu Fay Zonu (DAFZ) ile uyum göstermektedir. Anomalilere neden olan kaynak derinliklerinin arastırılması için spektral analiz tekniklerinden güç spektrumu yönteminden yararlanılmıstır. Çalısma alanında ortalama kabuk derinligi 44 km olarak bulunmustur. Gravite verilerden GD-KB yönünde alınan kesit degerleri degerlendirilerek Talwani modelleme teknigine göre iki boyutlu bir kabuk modeli olusturulmustur. Buna göre çalısma alanında kabuk kalınlıgı güneyden kuzeye dogru 38 km ile 51 km arasında degisim göstermektedir. DAFZ’ni...

Geophysical Research Letters, 2015

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Proceedings, 2013

ABSTRACT This study focuses on upper crustal studies such as earthquake locations (especially mic... more ABSTRACT This study focuses on upper crustal studies such as earthquake locations (especially micro-seismic activity), moment tensor inversions and receiver function analysis. Accurate earthquake locations will eventually lead to high-resolution seismic images of NAF including both the northern and the southern branches in the upper crust.In this study, 722 earthquakes within the time period of 09 May – 17 September 2012 were located. Furthermore, the crustal structure beneath the DANA Array is investigated using receiver functions obtained from the teleseismic recordings from a total of 73 broadband stations. Calculated Moho depth beneath the most of stations is between 33 and 36 km.