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a) Coda lapse time windows and b) fitted decay lines of RMS amplitudes and Qc values at 7 different central frequencies for event ID. 2010.04.24 05:15:07. Key: OT = Origin time, PT = P wave arrival time, ST = S wave arrival time.
Source publication
A dataset obtained from six broadband stations of 111 small- to moderate-sized local events that occurred between 2010
and 2018 was analyzed to reveal the frequency-dependent seismic body (body-Q) and coda (coda-Q) wave attenuation characteristics
of three tectonic branches of the Karlıova Triple Junction: the Varto Fault Zone (VFZ), North Anatol...
Context in source publication
Context 1
... ratios were calculated by dividing the RMS amplitudes of the 10-s signal data portion in the middle of the coda window into the portion before the first arrival of P waves as noise. The lapse time windows starting at twice the travel time of the S-wave onset were used here ( Aki and Chouet, 1975;Rautian and Khalturin, 1978; Aki, 1980) ( Figure 3). It is an important challenge of extracting P wave coda part based upon the fact that P coda waves could be overlapped by S waves at low source-receiver distances; thus, in such studies, S coda waves are generally preferred rather than P coda waves (Sertçelik and Güleroğlu, 2017). ...
Citations
... Strong-motion stations with a hypocentral distance of <150 km were used. The attenuation factors and the distance correction were calculated using the frequency-dependent Q-value of Q 61:6f 0:81 (Demirci, 2019) with the S-wave velocity along the path of 3.3 km/s and the geometrical spreading of the body wave. The corner frequencies of the three events were estimated to fit the observed spectral ratios to the model spectral ratios using the same method as that of Satoh (2023a). ...
The 2023 Mw 7.8 Türkiye earthquake caused severe damage in near-fault regions. The broadband source model, which is important for predicting strong motions in near-fault regions, was estimated. First, high-frequency (3–10 Hz) source imaging was performed through isochrone backprojection using near-field strong-motion records. Four segments were set, consisting of three segments along the East Anatolian fault and one segment along the splay fault where the rupture started. The estimated rupture velocities at the four segments were 2.6–3.3 km/s. The broadband (0.2–10 Hz) source model was then estimated using the empirical Green’s function method. The locations of eight strong-motion generation areas (SMGAs) of the broadband source model were searched with reference to the large brightness area estimated by isochrone backprojection. The source parameters of the SMGAs were estimated to fit the calculated acceleration and velocity envelopes at 21 strong-motion stations to the observed ones. The locations of the SMGAs were mostly consistent with the large slip area estimated by previous studies from long-period waveforms or static data, except for one SMGA with the highest Brune’s stress drop on the splay fault. The highest stress drop caused large ground motions near the splay fault, for which the supershear rupture has been suggested by previous studies. Ground motions were reproduced except for some stations affected by the fling-steps or nonlinear site effects. Although the SMGAs were not located near the southern side of the southwestern segment in Hatay Province, the large ground motions at shorter than about 2 s were mostly simulated. Large empirical site amplification factors estimated in this study must play a role on the large ground motions. The forward rupture directivity effects, with a rupture velocity of 3.3 km/s as large as the S-wave velocity, were also responsible for the large ground motions there.
... This fault zone is connected with the eastern section of the NAFZ, extending by 50-55 km, and can be subdivided into six segments (Emre et al., 2018;Karaoglu et al., 2017). In this fault zone, two destructive earthquakes (M W = 6.8 and M W = 6.2) occurred in August 1966 (Demirci, 2019). There are two major volcanic systems in the region, called Turnadag volcano and Varto caldera, showing a deep-seated reservoir at depths of about 15-18 km. ...
... However, the low b-values and positive Coulomb stress changes appear in and around the VFZ, EFZ, YS, KS, and KFZ (Fig. 9). The low attenuation and high-frequency dependency values can be attributed to the energy loss as a result of heterogeneity, intensity of tectonic activity, high earthquake activity, and volcanic activity (Demirci, 2019). Concerning this, lower attenuation and higher frequency dependency values are observed around the KTJ. ...
... Concerning this, lower attenuation and higher frequency dependency values are observed around the KTJ. This region experienced destructive earthquakes such as the 1939 Erzincan (M = 7.9), 1949 Yedisu-Bingöl (M = 7.0), 1971 Bingöl (M = 6.8), and 1966 Karlıova-Bingöl (M = 6.2), which may have been associated with the abundant distribution of volcanic deposits of the Varto volcano to the north of the VFZ, the high heterogeneity with a complex crustal structure, the presence of a high-density fracture mechanism, and the intense faulting and compression effect (Aydın, 2022;Demirci, 2019;Sertçelik, 2012 The results reveal that Coulomb stress values are scattered around the Varto caldera and Turnadag volcano at the lower depths of the upper crust. Both negative and positive Coulomb stress values can be observed under these volcanoes. ...
The Yedisu Seismic Gap is one of the most important seismic gaps throughout the North Anatolian Fault Zone since it has not produced destructive earthquakes for a long time. To analyze the characteristics of future seismic hazards, the interrelationships between seismotectonic b-values, Coulomb stress changes, and S-wave velocity models of crust are presented in and around the Yedisu Seismic Gap located northwest of the Karlıova Triple Junction. For this purpose, the most up-to-date earthquake catalog and the focal mechanism solutions of recent earthquakes are used to image the different depth intervals. Results show that the relatively positive stresses are accumulating along the Varto Fault Zone and Kargapazarı and Yedisu Segments between 5 and 15 km depth intervals. At the same time, the lower b-values between 0.6 and 1.0 are found in the same segments. However, in the volcanic regions around the Karlıova Triple Junction, the low S-wave velocity zones may be related to high b-values, negative stress changes, and volcanic structures. The region between the Turnadağ volcano and the Varto caldera shows scattered stress and b-value changes in the upper crust. Moreover, the probability of earthquakes for Mw = 6.0, 7.0, and 7.7 in the intermediate term (10 years) is estimated as ~ 65%, ~ 17%, and ~ 5%, respectively. Recurrence of earthquakes with Mw = 6.0, 7.0, and 7.7 are calculated as ~ 10, ~ 55, and ~ 187 years, respectively. Consequently, the regions characterized by low strong b-values and positive stress loading reveal high earthquake hazard potential on the whole in the next decade.
... For all other cases, the separation is almost impossible, and the only measurable (unbiased) parameter is Q c . Thus, despite the problems of interpreting Q c , it still remains a widely measured parameter due to the mathematical simplicity of the model and the stability of the results, and numerous studies show a correlation between Q c and crustal heterogeneity in the lithosphere like some recent studies (e.g., Havskov et al. 2016;Sato et al.. 2012;Dasović et al. 2013;Boulanouar et al. 2013;Meirova and Pinsky 2014;Akyol 2015;Hasemi et al. 2015;Bachura and Fischer 2016;Dobrynina et al. 2016;Bora and Biswas 2017;Naghavi et al. 2017;Giampiccolo and Tiziana 2018;Vargas et al. 2018;Blanke et al. 2019;Demirci 2019;Yavuz andBaris 2019: Novelo-Casanova et al. 2020;Sivaram and Gupta 2022). So, in this study we will use the CWD method to obtain Q c . ...
Coda Q has been studied in the Northwest Caucasus region using 267 earthquakes and 17 stations from the network of the Geophysical Survey, Russian Academy of Sciences. This is the first Qc study for the region using such a large dataset. The average frequency-dependent coda Q relationship is Qc=90±21·f1.02±0.11\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Q_c\;=\;90\;\pm\;21\cdot f^{1.02\pm0.11}$$\end{document} . This value compares closely to other similar tectonic areas in the world where the same processing parameter had been used. Three specific zones, two in the Greater Caucasus tectonic area and one east of the Ciscaucasian trough area, were studied separately. There was a clear difference in Qc between the zones, particularly for the Ciscaucasian trough area which shows a higher Qc than the 2 other zones. However, the difference between the zones became smaller when using long lapse times tending to give a constant Qc as a function of lapse time. For a longer lapse time, it is assumed that a large part of the coda waves passes the mantle. The 2 zones in Greater Caucasus now had a similar Qc while the East zone in the Ciscaucasian trough still gave the highest values. We contribute this difference to differences in attenuation in the mantle under the two tectonic areas. In our area, there is then a clear difference in Qc for the 3 study areas in the crust but in the mantle the difference is mainly between the two tectonic zones.
... This interaction is the main reason for the development of important seismic sources in and around Türkiye. North Anatolian Fault Zone, East Anatolian Fault Zone and Aegean Graben System are known as effective seismic sources (Çoban and Sayıl 2020, Aksoy et al. 2007, Demirci 2019, Bayik 202, Şengör and Yılmaz 1981, Bayer et al. 1989, Bosworth et al. 2005, Reilinger et al. 1997. As a result, Türkiye, which has such intense and complex tectonic elements, has been and will continue to be exposed to many earthquakes (Işık et al. 2023). ...
The high seismic risk has once again revealed in Türkiye with two major earthquakes that occurred on 06.02.2023, which took its place among the most destructive earthquakes in the last century. Totally, 65 earthquakes that occurred in the historical period in Türkiye were taken into account within the scope of this study. The seismic parameters were compared by considering the last two earthquake hazard maps for the epicenters of these earthquakes. Earthquake Intensity (I) of historical earthquakes were converted to Peak Ground Acceleration (PGA) by using suggested relations. Structural analyzes were performed for a sample reinforced-concrete building by using the obtained PGA's and predicted PGA's in the last two earthquake hazard maps. In the structural analysis, two different material groups such as low (C12-S220) and normal (C25-S420) were selected. As the material strength increased, the period value decreased, while the seismic capacity and stiffness increased. It has been determined that there are differences between the measured and proposed seismic risks for some earthquakes, and as a result, there are significant differences between the expected target displacement values from the structures. Therefore, it will not be possible to estimate the damage and to determine the building performance realistically. The main purpose of the study is to reveal whether the earthquake risk is adequately represented on seismic and structural parameters.
... The Bitlis Suture Belt is a complex that can be defined as the continent-continent and continent-ocean collision boundary, extending from the southeast of Turkey to the Zagros Mountains in Iran. It is characterized by a N-S trending compressional tectonic regime located to the east of the Karlıova triple junction (Aksoy et al. 2007;Demirci 2019;Bayik 2021). In addition to these, one of the important tectonic structures in Turkey is the Western Anatolian Graben System. ...
Significant loss of life and property has occurred as a result of many destructive earthquakes in both historical and instrumental periods in Turkey, which is located on the Alpine-Himalayan seismic belt. Past local earthquakes are an excellent tool to predict potential earthquakes in any region. Within the scope of this study, seismic parameters were obtained in the light of current data for a total of 62 earthquake epicenters with Ms ≥ 6 that occurred in the instrumental period in Turkey. Comparisons between seismic parameters were made on the last two earthquake hazard maps used in Turkey. In addition, the measured actual peak ground acceleration values for 16 earthquakes whose data can be accessed were compared with the current peak ground acceleration values as specified in the current Turkish Seismic Design Code. In order to compare the effectiveness of seismicity hazard map specified in previous and current Turkish Seismic Design Code, structural analysis of a reinforced-concrete building was carried out by using both the measured and current acceleration values according to the last two earthquake hazard maps. It has been determined that there are differences between the measured and proposed peak ground acceleration for some earthquakes. There are significant differences between the expected target structure displacement values as a result of structural analyses.
... Elde edilen sonuçlar yorumlanarak öneriler yapılmıştır. [10,11]. Bunların yanı sıra, ülkemizdeki önemli tektonik yapılardan biri Batı Anadolu Graben Sistemi'dir. ...
Bir bölgenin depremselliği, yerel zemin koşulları ve yapısal özellikler yapıların deprem etkisi altındaki
davranışlarını ve risklerini belirlemede kullanılan önemli parametrelerdir. Yapılar ile ilgili analizlerde o bölgenin
depremselliği, spektrum eğrileri ile ifade edilebilmektedir. 2019 yılında yürürlüğe giren Türkiye Bina Deprem
Yönetmeliği ile noktaya özel spektrum eğrileri kullanılmaya başlanmıştır. Bu çalışma kapsamında Türkiye’deki
yedi farklı coğrafik bölgeden birer il seçilerek coğrafik konumun hem deprem parametrelerine hem de yapı
performans hesaplamalarını hangi düzeyde etkilediği ortaya konmaya çalışılmıştır. Ankara, Antalya, Diyarbakır,
Erzurum İstanbul, İzmir ve Samsun illeri için 50 yılda aşılma olasılığı %10 (tekrarlanma periyodu 475 yıl) olan
ve Türkiye Bina Deprem Yönetmeliği’nde DD-2 olarak belirtilen yer hareket düzeyi ile yerel zemin sınıfı ZE
olarak dikkate alınmıştır. Her il için kısa periyot harita spektral ivme katsayısı, en büyük yer ivmesi, en büyük yer
hızı, yerel zemin etki katsayıları, tasarım spektral ivme katsayıları ile yatay ve düşey elastik spektrum eğrisi için
hesaplamalar yapılmıştır. Çalışma ile farklı geometrik konumlarda bulunan fakat aynı zemin özellikleri ve yer
hareketi olmasına rağmen deprem parametrelerinin değişimi incelenmiştir. Coğrafik konumun yapı performans
hesaplamalarına etkisi ortaya koymak adına tüm illerde aynı yapısal özelliklere sahip yedi katlı betonarme bir yapı
seçilmiştir. Seçilen örnek betonarme yapı için her il için analizler gerçekleştirilmiştir. Yapı analizinde zemin
özelliklerinin dikkate alındığı statik adaptif itme analiz kullanılmıştır. Elde edilen tüm sonuç değerleri
karşılaştırılmıştır. Coğrafik konum değişikliği hem deprem parametrelerini hem de yapısal analiz sonuçları
doğrudan etkilemektedir. Çalışma, Türkiye Bina Deprem Yönetmeliğinin sahaya özel deprem parametrelerinin bir
kazanım olduğu sonucunu ortaya çıkarmıştır. Herhangi bir noktada yerel zemin koşulları ve yapısal özellikler aynı
olsa bile bölgenin depremsellik öğelerinin dikkate alınması gerekmektedir.
Coda Q has been studied in the North-West Caucasus region using 267 earthquakes and 17 stations from the network of the Geophysical Survey, Russian Academy of Sciences. This is the first Q c study for the region using such a large dataset. The average frequency-dependent coda Q relationship is Q c =90±21∙ f 1.02±0.11 . This value compares closely to other similar tectonic areas in the world where the same processing parameter had been used. Three specific zones, two in the Greater Caucasus tectonic area and one east of the Ciscaucasian trough area, were studied separately. There was a clear difference in Q c between the zones, particularly for the Ciscaucasian trough area which shows a higher Q c than the 2 other zones. However, the difference between the zones became smaller when using long lapse times tending to give a constant Q c as a function of lapse time. For longer lapse time it is assumed that a large part of the coda waves passes the mantle. The 2 zones in Greater Caucasus now had a similar Q c while the East zone in the Ciscaucasian trough still gave the highest values. We contribute this difference to differences in attenuation in the mantle under the two tectonic areas. In our area, there is then a clear difference in Q c for the 3 study areas in the crust but in the mantle the difference is mainly between the two tectonic zones.
A study of seismic body wave attenuation was carried out for the Valle Medio del Magdalena (VMM) basin, Colombia. A total of 326 high-quality local earthquakes were used to calculate coda Q (Qc) values, and 1463 high-quality local earthquakes were used to calculate Q scattering (Qs), Q intrinsic (Qi), Q total (QT), and other attenuation parameters. The average Qc ranged from 47 for 2.0 Hz to 904 for 12 Hz. The average Q-frequency relation (Qc -f) for the VMM basin was Qc = 50 ± 6.4 f1.1±0.08. Qi, Qs, and QT ranged from 4, 6, and 2.4 for 2.0 Hz to 420,483, and 224 for 12 Hz, respectively, depending on the region, epicentral distance and depth. Intrinsic absorption was predominant over scattering in the VMM basin at shallow crustal depths, although scattering was also remarkable. Qc value is similar to Qs for low frequencies ( ≤ 2 Hz). For high frequencies ( ≥ 3 Hz), Qc is much higher than Qi, Qs, and QT, indicating that at low frequencies Qc is reflecting the scattering process occurring at VMM. In addition, it means that single-scattering approach is valid to measure attenuation at VMM for low frequencies but not for high frequencies, where the attenuation is underestimated by using Qc. The spatial distribution of the average Qi, Qs, and QT shows that, in general, the VMM region has high attenuation at shallow crustal depths, with higher attenuation to the south and north. This high attenuation is possibly due to the presence of oil and water reservoirs as well as the presence of thick sedimentary deposits compared with the surrounding plutonic rocks. The results of this study will be useful for further seismic source, strong motion and seismic hazard studies in the VMM region.
