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Location of the June 27, 1998 Adana earthquake and the tectonic setting of the northeastern corner of the East Mediterranean region. All active faults shown are left lateral strike slip with the exception of KF, which has a significant normal component. Abbreviations on the inset are AB=Adana Basin (stippled); DSF=Dead Sea Fault; EAF=East Anatolian Fault; EF=Ecemi@BULLET Fault; GFZ=GOksun Fault Zone; HF=Hatay Fault; IB=Iskenderun Basin; KF=Karasu Fault; KT=Kyrenea Thrust (cross-hatched); MAT=Misis-Andirin Trust (crosshatched), and YF=Yumurtalik Fault.
Source publication
We analyze the main and aftershocks of the June 27, 1998 Adana earthquake using data from the short-period Cilician seismograph network in order to investigate the seismotectonics of the northeastern Mediterranean region. The mainshock is found to have a pure left lateral strike-slip mechanism (strike=50°, dip=85°, rake=10°, M0=3.63×1018Nm). The in...
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Citations
... The slip distribution models of both earthquakes were examined using a finite-fault source inversion method developed by Hartzell and Heaton (1983) and the 1-D crustal velocity model (after Aktar et al., 2000;Ergin et al. 2004) to calculate the Green's functions shown in Table 4. The velocity model is performed using the recordings of a local seismic network installed in the Cilician-Adana region, the SSW-section of the first earthquake rupture. ...
... ,Aktar et al. (2000),Utkucu et al. (2018), and Global Centroid Moment Tensor (GCMT) catalog(Utkucu et al., 2018 and references therein). Faults (thin lines in black) are compiled fromŞaroğlu et al. (1992) and Duman andEmre (2013). ...
Abstract
On 6th February 2023 (UTC), two consecutive and catastrophic earthquakes with moment
magnitudes (Mw) 7.8 and 7.7 struck the Maras Triple Junction (MTJ) region in SE Anatolia
along with dozens of aftershocks, causing numerous casualties and significant building
damage, and generating the most complex and longest surface ruptures ever observed in
Turkey. The main driving mechanisms of this complex double event are still unresolved and
remain controversial, even though they are likely linked with conventional fault activations,
recurrence intervals and seismic gaps. Here, the aim was to gain insight into the source
regimes and rupture processes of both events and their relationship with resolved fault focal
solutions for the observed aftershocks, and to present an interpretation that accounts for the
most puzzling aspects of the fault rupture models. In line with this, the co-seismic slip
distributions of these two events were examined by joint analyses of centroid moment tensor
(CMT) and finite-fault source inversions using regional and teleseismic broadband
observations. Inversion results indicate that both earthquakes were left-lateral strike-slip
events, and the main ruptures extended mainly from close to NNE to SSW and E to W, with
maximum slips of ~6.5-10 m, mostly confined to a shallow depth range of ≤ ~10-15 km and
extending to the surface, indicating bilateral source processes with an average rupture velocity
of ~3.5-5.5 km/s. The estimated total seismic moment range was 4.94-8.22 x 1020 N m,
associated with ~352-152 km long (along strike) and ~25 km wide (along dip) fault planes at
focal depth of ~10 km. Regional CMT results indicate nearly pure normal-slip and left-lateral
normal oblique-slip focal mechanisms and shallow centroid depths (≤ ~15 km) for the early
aftershock distribution that are obviously complementary with the co-seismic bilateral rupture
propagations. This result highlights that double pull-apart branching of focal mechanisms for
aftershock occurrence implies interacting fault ruptures embedded in the MTJ area, where two
sub-/supershear-rupturing faults meet, thus explaining multiple segmentation and seismogenic
evolutions of two interrelated mainshocks, i.e. “triple junction earthquakes”. The results
reveal that the MTJ tends to migrate to the SSW and likely drives the SSW-stepping of the
left-lateral strike-slip shear (~136 km). This accounts for the peak slips, long co-seismic fault
ruptures and the associated faulting styles. Hence, the co-seismic faulting apparently
distributed across the MTJ may reflect triple junction migration, and thus large extension at
the core of the Anatolian-Arabian plates, leading to very high seismic hazard in similar
junction regions of the country.
... During the instrumental period in which seismic data can better constrain earthquake source details, the magnitude-6.2 Ceyhan earthquake that struck on June 27, 1998 is the largest event to affect the Adana Basin (Aktar et al., 2000;Ergin et al., 2004). The earthquake ruptured the Misis-Ceyhan Fault, and both the epicenter and source mechanism of the mainshock are well constrained by Aktar et al. (2000), providing clear evidence of left-lateral strike-slip motion. ...
... Ceyhan earthquake that struck on June 27, 1998 is the largest event to affect the Adana Basin (Aktar et al., 2000;Ergin et al., 2004). The earthquake ruptured the Misis-Ceyhan Fault, and both the epicenter and source mechanism of the mainshock are well constrained by Aktar et al. (2000), providing clear evidence of left-lateral strike-slip motion. Similarly, the Jan. 3, 1994 Kurtkulağı event of magnitude 5.0, located near the Yumurtalık Fault, also shows strike-slip faulting (Aktar et al., 1994;Ergin et al., 2004). ...
... Şekil 3. Kilikya Sismograf Ağı tarafından ana şok (yıldız ile simgelenmiştir) sonrası bölgede bir aylık dönem içerisinde gözlenmiş artçı şoklar (Aftershocks were observed within a month period in the region after the mainshock (symbolized with a star) by the Cilician Seismograph Network) (Aktar et al., 2000) Şekil 4. Kilikya Sismograf Ağı tarafından kaydedilmiş 27 Haziran 1998 Adana depremi artçı şokların dağılımı. Derinlik kesitleri A-A' ve B-B' konumları (Aktar vd., 2000'den değiştirilmiştir). ...
... GFZ, Göksu Fay Zonu' nu; YF, Yumurtalık Fay Zonu' nu temsil etmektedir (Distribution of aftershocks from the 27 June 1998 Adana earthquake recorded by the Cilicia Seismograph Network. Depth sections A-A' and B-B' positions (modified from Aktar et al., 2000). GFZ (2000) tarafından belirlenen odak mekanizması çözümleri. ...
... Faylanma parametreleri için Tablo 1'e bakınız. USGS: Amerikan Jeolojik Araştırmalar Kurumu, HARVARD: Harvard Üniversitesi (According to Harvard, USGS, Aktar et al. (2000), and Arpacıoğlu (2000) [Haskell, 1960;Haskel, 1962;Bouchon, 1976) ile çok-tabakalı yapılar kullanılmıştır. ...
Doğu Anadolu Fay Zonu uzanımının tartışma konusu olduğu Kilikya Havzasında 27 Haziran 1998 yılında orta büyüklükte (Mw=6.2) bir deprem meydana gelmiştir. Çalışmada depremin kaynak parametreleri belirlenmesi amacıyla deprem kaynağı nokta-kaynak ters çözüm yöntemi telesismik P ve SH dalga şekilleri kullanılarak yapılmıştır. Nokta-kaynak modellemesinde gözlenmiş-kuramsal dalga şekilleri arasında yaklaşık olarak aynı derecede uyum gözlenmiştir. Böylece tek alt olaylı bir kırılma süreci nokta kaynak gösteriminde depremin kırılma süreci olarak kabul edilmiştir. Aynı zamanda nokta kaynak modellemesi denemeleri 24 km’ de kaynak lokasyonuyla derin alt kabukta bir kırılmayı gerektirmektedir. Kaynak mekanizması çözümünde KD-GB yönelimli (doğrultu=57o, eğim=70o ve kayma açısı=20o) düğüm düzlemi fay düzlemi olarak belirlenmiştir ve yakındaki Göksu fay zonuyla paralellikten sapmış bir görüntü vermiştir. Nokta kaynak modeli için sismik moment 2.24X1018 Nm (Mw=6.2) olarak hesaplanmıştır. Telesismik modelleme sonuçları bir bütün olarak deprem kırılmasının Göksu Fay Zonu (GFZ)’ nun yeryüzüne ulaşmayan, GD eğimli ve GFZ’ nin yüzeydeki haritalanmış izinden farklı doğrultulu bir dalı üzerinde gerçekleştiğini önermektedir.
... These earthquakes are the 27 June 1998 Adana and the 1 May 2003 Bingöl earthquakes (Fig. 1). No Toksöz et al. 1978, Taymaz et al. 1991, Pınar 1995, Aktar et al. 2000, Pınar et al. 2007 finite-fault rupture models from teleseismic velocities have been published so far for both studied earthquakes. Therefore, finite-fault rupture models would be important to understand rupture properties of these earthquakes that produced no surface ruptures. ...
... On 27 June 1998, a moderately large earthquake hit the Adana basin located along Turkey's Mediterranean coast with heavy damage and fatalities ( Figs. 1 and 3). Seismotectonics of this region is controlled by the convergence of the Anatolian, African, and Arabian plate and the region represents a distributed plate boundary zone (Ergin 1999;Aktar et al. 2000;Westaway 2004;Seyrek et al. 2014). Collision regime between the Arabian and Anatolian plates in the east of the source region turns into a subduction-dominated regime between the African and Anatolian plates in the west. ...
... Thus, the data provided by the network, which was further enhanced by four additional seismographs for monitoring the aftershocks following the mainshock, led to well-constrained determination of both the mainshock and the aftershock locations, revealing an unusual feature of the earthquake as a crustal event. The mainshock hypocenter was located at a depth of 32 km while the aftershocks covered a depth range of 17-37 km, comprising two distinct clusters (Aktar et al. 2000;Ergin et al. 2004). Besides, Harvard CMT solution indicates a centroid depth at 29.5 km ( Table 1). ...
The East Anatolian Fault Zone is a continental transform fault accommodating westward motion of the Anatolian fault. This study aims to investigate the source properties of two moderately large and damaging earthquakes which occurred along the transform fault in the last two decades using the teleseismic broadband P and SH body waveforms. The first earthquake, the 27 June 1998 Adana earthquake, occurred beneath the Adana basin, located close to the eastern extreme of Turkey’s Mediterranean coast. The faulting associated with the 1998 Adana earthquake is unilateral to the NE and confined to depths below 15 km with a length of 30 km along the strike (53°) and a dipping of 81° SE. The fixed-rake models fit the data less well than the variable-rake model. The main slip area centered at depth of about 27 km and to the NE of the hypocenter, covering a circular area of 10 km in diameter with a peak slip of about 60 cm. The slip model yields a seismic moment of 3.5 × 10¹⁸ N-m (Mw ≅ 6.4). The second earthquake, the 1 May 2003 Bingöl earthquake, occurred along a dextral conjugate fault of the East Anatolian Fault Zone. The preferred slip model with a seismic moment of 4.1 × 10¹⁸ N-m (Mw ≅ 6.4) suggests that the rupture was unilateral toward SE and was controlled by a failure of large asperity roughly circular in shape and centered at a depth of 5 km with peak displacement of about 55 cm. Our results suggest that the 1998 Adana earthquake did not occur on the mapped Göksun Yakapınar Fault Zone but rather on a SE dipping unmapped fault that may be a split fault of it and buried under the thick (about 6 km) deposits of the Adana basin. For the 2003 Bingöl earthquake, the final slip model requires a rupture plane having 15° different strike than the most possible mapped fault.
... Although some of the events in the Karlıova have hypocentres deeper than 20 km, the overall seismicity of the EAF zone is less than 20 km Bulut et al. 2012). However, seismological data show that the earthquakes on the western half of the SMF system are deep-seated events that reach down to 30 km in the Cilicia region (Aktar et al. 2000;Ergin et al. 2004). In contrast, the earthquakes (Ergin et al. 2004) located within the Düziçi-Osmaniye fault zone are characterized by shallow hypocentres of *5 km. ...
... At the western part of the EAF in Cilicia region, the earthquake events appear to originate from strike-slip and normal faults representing the plate boundary between the African, Arabian and Anatolian plates (Aktar et al. 2000;Ergin et al. 2004). While strikeslip events occur in the lower crust, normal events are located in the upper crust relatively shallow. ...
Turkey is located in one of the most seismically active regions in the world. Characterizing seismic source zones in this region requires evaluation and integration of geological, geophysical, seismological and geodetical data. This first seismotectonic database for Turkey presented herein was prepared, under the framework of the National Earthquake Strategy and Action Plan—2023. The geographic information system (GIS)-based database includes maps of active faults, catalogues of instrumental and historical earthquakes, moment tensor solutions and data on crustal thickness. On the basis of these data, 18 major seismotectonic zones were delineated for Turkey and the surrounding region. The compilation and storage of the seismotectonic data sets in a digital GIS will allow analyses and systematic updates as new data accrete over time.
... Continuous monitoring over the years has shown that deep seismic activity persists only at certain locations around the earth and under very specific conditions that allow brittle deformation in the lower crust. The kinematic analysis of these deep events typically gives a pure double couple mechanism indicating shear dislocation similar to the shallow earthquakes (Deichmann, 1992;Singer et al., 2014;Bonner et al., 2003;Aktar et al., 2000). The controversial aspect of lower crust seismicity is the temperature conditions and associated modifications of rock rheology that is expected to prevent the brittle fracture (Chen, 1988). ...
... It is clear that the lower crustal seismicity in the Adana Basin is unique and has to be interpreted separately. Aktar et al. (2000), reported the lower crustal seismic activity of the Adana Basin by focusing on the damaging Adana earthquake of 1998, Mw = 6.2. This study provided clear evidence that both the main event and the aftershocks were all located below a depth of 20 km. ...
... This fact excludes the connection of the deep seismicity to the Cyprian subduction process, since the latter extends well beyond the limits of the Adana Basin (Rotstein and Kafka, 1982). Both studies, by Aktar et al. (2000) and Ergin et al. (2004), support that deep activity was generated by a single fault, namely the NE-SW trending Goksu fault (GF), first spotted in seismic profiles by Perincek et al. (1987). The detailed study of the earthquake source showed a left lateral strike-slip mechanism, which is in full agreement with the neighboring fault systems and the regional tectonics described by Şengör et al. (1985). ...
... Although some of the events in the Karlıova have hypocentres deeper than 20 km, the overall seismicity of the EAF zone is less than 20 km Bulut et al. 2012). However, seismological data show that the earthquakes on the western half of the SMF system are deep-seated events that reach down to 30 km in the Cilicia region (Aktar et al. 2000;Ergin et al. 2004). In contrast, the earthquakes (Ergin et al. 2004) located within the Düziçi-Osmaniye fault zone are characterized by shallow hypocentres of *5 km. ...
... At the western part of the EAF in Cilicia region, the earthquake events appear to originate from strike-slip and normal faults representing the plate boundary between the African, Arabian and Anatolian plates (Aktar et al. 2000;Ergin et al. 2004). While strikeslip events occur in the lower crust, normal events are located in the upper crust relatively shallow. ...
GIRIŞ
Türkiye Alp-Himalaya Sıradağı içinde Doğu Akdeniz bölgesinde bulunur. Batı Avrupa’dan Asya’ya yaklaşık 9 bin km uzunluktaki bu sıradağın oluşumu günümüzde de devam etmektedir. Bu oluşum sırasında meydana gelen tektonik olaylar nedeniyle Alp-Himalaya Sıradağı dünyanın en aktif deprem kuşaklarından birisidir. Türkiye’nin sismotektonik özellikleri içinde bulunduğu Doğu Akdeniz bölgesindeki güncel levha tektoniğiyle doğrudan ilişkilidir. Bu bölgede dünya ölçeğindeki litosferik levhalar birbiriyle etkileşim içinde bulunurlar.
Bunlardan Arabistan ve Avrasya levhalarının çarpışması sonucu ortaya çıkan Anadolu levhası etrafında veya içinde meydana gelen tektonik deformasyonlar ve bunların neden olduğu deprem etkinliği Türkiye’nin sismotektoniğini doğrudan kontrol etmektedir.
Anadolu levhası Doğu Akdeniz bölgesinde devam eden levha kinematiği içinde saatin tersi yönünde dönerek batıya doğru hareket eder ve litosferik Afrika levhası üzerine itilir. Bu tektonik süreçte meydana gelen deformasyonların çoğunluğu Anadolu levhasını kuzey ve güneyden sınırlayan levha içi transform fayları tarafından karşılanır. Bu transform faylar, sırasıyla, Kuzey Anadolu Fayı (KAF) ve Doğu Anadolu Fayı (DAF) olarak adlandırılır. Diğer taraftan Akdeniz’de Anadolu ile Afrika levhaları arasındaki yitimi karşılayan Ege ve Kıbrıs yayları ile Afrika ve Arabistan levhaları arasında transform sınır oluşturan Ölü Deniz Fay (ÖDF) zonu bölgenin diğer deprem kaynağı olan devasa yapısal unsurlardır.
Türkiye ve yakın çevresinde tarihsel ve aletsel dönemlerde çok sayıda deprem kayıt altına alınmıştır. Anadolu’da 1900 öncesi tarihsel dönemde 200’den fazla yıkıcı depremin meydana geldiği ve bazı medeniyetleri ciddi şekilde etkilediği, hatta yıkılmalarına neden olduğu bilinmektedir. Benzer şekilde aletsel dönemde 1900-2012 yılları arasında Türkiye ve yakın çevresinde 203 büyük deprem (Mw ≥ 6,0) kaydedilmiştir. Bu depremler bölgede 90 binden fazla kişinin ölümüne neden olmuş, ülke ekonomisini etkileyecek düzeyde 50 milyar dolardan fazla zarara yol açmıştır. Bu afetlerin toplum üzerinde yaratmış olduğu psiko-sosyolojik etki ise çok daha büyük ve ölçülemeyecek boyuttadır.
2009 yılında Afet ve Acil Durum Yönetimi Başkanlığı’nın kurulması ülkede meydana gelen doğa-afetlerinin etkisini azaltma konusunda yeni bir yapılanmayı, mevcut politika ve planların gözden geçirilmesi gerekliliğini de beraberinde getirmiştir. Bu bağlamda önceki ulusal planların deneyimi ışığında yeni bir Ulusal Deprem Stratejisi ve Eylem Planı (UDSEP-2023) oluşturulmuştur. UDSEP-2023 planı 2011 yılında Afet Yüksek Heyeti tarafından imzalanmış ve ülkede deprem zararlarının azaltılması çalışmalarında izlenecek resmi bir belge niteliğini kazanmıştır. UDSEP-2023’te deprem afeti nedeniyle meydana gelen kayıp ve zararların azaltılmasında gerek duyulan bilgi alt yapısının oluşturulması için deprem kaynağı diri fayların yeniden değerlendirilmesinden bunların neden olabilecekleri tehlikenin tanımlanmasına uzanan bir dizi araştırma başlatılmıştır. Deprem jeolojisi ve sismoloji konularında başlatılan bu araştırmalar; Türkiye diri fay, sismotektonik ve deprem tehlike haritalarının hazırlanması, ülke genelindeki diri faylarda paleosismolojik araştırmaların tamamlanması, depremle tetiklenen sıvılaşma ve tsunami konularında temel bilgi altyapısının oluşturulması için araştırmaların yapılması olarak sıralanabilir.
Sismik tehlike değerlendirmeleri depreme dayanıklı tasarım politikaları, risk analizleri ve arazi kullanım planlamaları için vazgeçilmezdir. Bu değerlendirmelerin temel aşaması olan sismik tehlike haritalarının hazırlanabilmesi için yeni teknoloji ve bilgi birikimine dayalı hazırlanmış veya güncellenmiş sismotektonik bilgi alt yapısını gerektirmektedir.
Sismotektonik harita ve ilgili veri tabanı deprem tehlike analizlerinde gerekli jeolojik ve sismolojik bilgileri sağlar. Bunlarla birlikte çok disiplinli bir yaklaşım gerektiren deprem tehlike analizlerinin başarısını arttırmak amacıyla, bu harita veya veri tabanlarına diğer jeofizik, jeodezik ve benzeri her türlü bilgi de eklenmektedir. Türkiye için sismik tehlike modelleri öneren çalışmalar sınırlıdır (Yarar vd., 1980; Erdik ve Öner, 1982; Erdik vd., 1982, 1985, 1999; Kayabalı, 2002). Son yıllarda sismik tehlike durumunu Avrupa boyutunda ele alan SHARE projesi (Woessner vd., 2015) ve Orta Doğu bölgesinin sismik tehlikesini araştıran EMME projesi (http://www.emme-gem.org/) ortak ülke olarak bulunduğumuz bölgesel ölçekte yapılan sismik tehlike çalışmalarına örnek olarak gösterilebilir.
Bu araştırmada ulusal bir katılımla hazırlanan Türkiye Sismotektonik Haritası ve Veri Tabanı tanıtılmaktadır. Türkiye sismotektonik veri tabanı oluşturulması ve ilgili haritaların hazırlanması UDSEP-2023 kapsamında Maden Tetkik ve Arama (MTA) Genel Müdürlüğü sorumluğunda gerçekleştirilmiştir. Projede Afet ve Acil Durum Yönetimi Başkanlığı (AFAD), Kandilli Rasathanesi ve Deprem Araştırma Enstitüsü (KRDAE) ve Harita Genel Komutanlığı (HGK) kurumsal ortaklar olarak katkı koymuşlardır. Ayrıca üniversitelerden konularında uzman araştırıcılar projeye kişisel katılımlarla katkı koymuşlardır. Proje kapsamında hazırlanan veri tabanı jeolojik, jeofizik, sismolojik ve jeodezik bilgilerden oluşan beş veri grubunu kapsar. Bunlar diri faylar, aletsel ve tarihsel deprem katalogları, moment tensör kataloğu ve kabuk kalınlığı bilgileridir. Bu veri tabanı kullanılarak 18 paftadan oluşan 1:500.000 ölçekli Türkiye Sismotektonik Haritası hazırlanmıştır. Bunların dışında 1:1.250.000 ölçekli ülkenin tamamını bir bütün olarak gösteren Türkiye Sismotektonik Haritası da hazırlanmıştır. Türkiye sismotektonik haritası ve ilgili veri tabanı ülkede sismik tehlike analizlerinde gerekli bilgileri sağlamaktadır. CBS ortamında hazırlanmış olan bu veri tabanı sistematik veri eklenebilir ve yenilenebilir bir bilgi altyapısıdır.
... However, there is insufficient information in the literature to attribute these events to a specific fault segment. Regarding the instrumental period, the June 27, 1998 Ceyhan earthquake (M:6.3) is the largest event in the Adana Basin and it occurred on the Misis-Ceyhan Fault (Aktar et al., 2000;Ergin et al., 2004). The epicenter location and the source mechanism of the mainshock are well constrained by Aktar et al. (2000) providing clear evidence of pure left lateral strike-slip motion (Fig. 2). ...
... Regarding the instrumental period, the June 27, 1998 Ceyhan earthquake (M:6.3) is the largest event in the Adana Basin and it occurred on the Misis-Ceyhan Fault (Aktar et al., 2000;Ergin et al., 2004). The epicenter location and the source mechanism of the mainshock are well constrained by Aktar et al. (2000) providing clear evidence of pure left lateral strike-slip motion (Fig. 2). Similarly, the January, 3rd 1994 Kurtkulagı event (M b :5.0), located near the Yumurtalık Fault, also shows strike slip faulting (Aktar et al., 1994;Ergin et al., 2004). ...
The left lateral strike slip East Anatolian Fault Zone (EAFZ) is the main structural link between the North Anatolian Fault Zone (NAFZ) in north and subduction in the Mediterranean Sea and the transform Dead Sea Fault Zone (DSFZ) in south. We studied the southwestern continuation of the EAFZ using combined field investigations including geomorphology, geology and paleoseismology. Mapping of offset drainages, lineaments, shutter ridges and fault planes in young geological units suggests existence of active faults between the Mediterranean coast and Türkoğlu where it intersects with the DSFZ. Yumurtalık and Toprakkale faults are the main tectonic structures and detailed examination of geological and geomorphological evidences suggest their Quaternary activity. Paleoseismic trenching on these faults provided evidence for at least two surface rupturing events in the last 9,000 yr. Detailed examination of paleo-valleys of the Ceyhan River suggests that the course of the river migrated due to the activity of the Toprakkale Fault. Obtained geological and geomorphological data indicates that the EAFZ continues across the Amanos Mountains and the slip transfer is mainly accommodated by the Toprakkale and Yumurtalık faults.
... Besides, it is a developing region both in population and industry, a tectonically active area and hence prone to seismic hazards. Several studies are performed or under progress to understand the subsurface structure (Aktar et al. 2000;Bakirci et al. 2014) of the region. The characterization of the quality of noise data and the ambient seismic noise levels of the region may contribute to the ongoing and future studies, such as tomography, array processing and H/V spectral ratio studies, based on ambient noise. ...
... Three main rivers occupy the Adana Basin and form a major deltaic complex in the region. The previous studies suggest a sediment thickness between 3km to 6km (Aktar et al. 2000). ...
We investigate the characteristics of background seismic noise levels in the Adana basin and its surroundings (Southern Turkey) by using seventeen broadband velocity seismometers operated by Kandilli Observatory Earthquake Research Institute (KOERI) of Bosphorus University and Earthquake Research Department (ERD) of Disaster and Emergency Management Presidency of Turkey. The probability density functions of power spectral densities are calculated and their mode values are mapped to observe the spatial variations in day and night times. We observe that the calculated noise levels are coherent in general with the low- and high-noise models of the Earth. We also show an example where noise levels change as a function of period in seasonal basis.
... The shear strain component of this oblique tectonic regime propagates southwest with relatively stronger values along the Aslanta¸s Fault Zone and south of it (Fig. 7). This area is seismically active (Aktar et al., 2000) with strain-rate values up to ∼80 nstrain/yr (Fig. 4) in the areas of Ceyhan-Yumurtalık, in close proximity to the Adana Mw6.2 earthquake epicentre in 1998 (Aktar et al., 2000), and in the area of 4. a) Resulting Central and Eastern Anatolian regional strain-rate field. The second invariant of horizontal strain represents the "magnitude" of strain and is defined as ...
... The shear strain component of this oblique tectonic regime propagates southwest with relatively stronger values along the Aslanta¸s Fault Zone and south of it (Fig. 7). This area is seismically active (Aktar et al., 2000) with strain-rate values up to ∼80 nstrain/yr (Fig. 4) in the areas of Ceyhan-Yumurtalık, in close proximity to the Adana Mw6.2 earthquake epicentre in 1998 (Aktar et al., 2000), and in the area of 4. a) Resulting Central and Eastern Anatolian regional strain-rate field. The second invariant of horizontal strain represents the "magnitude" of strain and is defined as ...
