Sürdürülebilir Kalkınma Amaçları
Yayınlar
- DüzeltmeAçık Erişim2023Corrigendum to Understanding university students WHO do not want to volunteer in disasters: A qualitative study from Türkiye [Int. J. Disaster Risk Reduc. 96 (2023) 103994] (International Journal of Disaster Risk Reduction (2023) 96, (S2212420923004740), (10.1016/j.ijdrr.2023.103994))
Demirbilek, Ömer; Öztürk, Serkan
The authors would like to add the below sentence in the Acknowledgment section. This study was produced from a doctoral thesis. The authors would like to apologise for any inconvenience caused. Ömer Demirbilek completed his undergraduate and graduate education in disaster management. He is currently pursuing his doctorate in disaster management. He works as a lecturer in the Disaster Management Department of Sinop University. Her areas of interest are disaster education, management, and volunteering in disasters. He has works published in international books and journals.
- Derleme MakaleAçık Erişim2022Depremlerden Sonraki Yeniden Yapılanma Süreci Üzerine Küresel Bir Araştırma: Çelik Prefabrik Malzeme Kullanımının Gerekliliği
Öztürk, Serkan; Etki Of, Nesibe
Bu çalışma kapsamında, çelik prefabrik yapıların yapısal özellikleri, Türkiye ve dünyada kullanım oranları ve niçin kullanılması gerektiği konuları bilimsel kaynaklar ortaya konularak araştırılmıştır. Farklı çalışmalardan elde edilen sonuçlar derlenerek, afet yönetimi için oldukça önemli olan yeniden yapılanma sürecine dikkat çekilmiştir. Çelik yapılar, hafif ve esnek malzemeler oldukları için depreme karşı mukavemet gösterirler. Bu ve daha birçok özelliğinden dolayı yüz ölçümünün büyük bir bölümü deprem bölgesinde yer alan ülkemizde konutların çelik prefabrikasyon ile yapılması gerekmektedir, çünkü bu yapıların depremlerde yıkılmadığı veya hasar alarak ayakta kaldığı literatürdeki birçok araştırma sonucunda kanıtlanmış olup afet yönetiminde ileri seviyede bulunan ülkeler tarafından da kanıksanmıştır. Türkiye ise çelik üretiminde dünyada yedinci sırada bulunmakla birlikte, bu durum yapı sektörüne yansımamaktadır. Depremler yaşandıktan sonra yeniden yapılanma sürecine gelindiğinde, yıkılan veya ağır hasar alan binaların yerine çelik konstrüksiyon binaları inşa etmek gerekmektedir. Bu strateji, kriz yönetiminin son basamağı olan yeniden yapılandırmada sağlam temeller atmayı sağlayacak ve risk yönetiminin ilk basamağı olan zarar azaltma evresindeki çalışmaları destekleyici nitelikte olacaktır. Bu bağlamda, önemli bir kazanım olarak, tam anlamda bir bütünleşik afet yönetimi döngüsü oluşturulabilecektir.
- MakaleYalnız künye2022Investigation of the Relationship among Fault Types, Focal Depths, and Ionospheric TEC Anomalies before Large Earthquakes between 2000 and 2020
Ulukavak, Mustafa; Yalçinkaya, Mualla; Kayikçi, Emine Tanir; Öztürk, Serkan; Kandemir, Raif; Karsli, Hakan
In this study, the relationships between possible ionospheric total electron content (TEC) anomalies and earthquake focal depths and fault types were investigated using 3,099 global earthquakes with Mw >= 6.0 between 2000 and 2020. The relationship between the ionospheric TEC changes and earthquakes has been previously discussed in the literature. However, very few studies have examined the relationship between the focal depths and the fault types of these earthquakes. In general, three indices, namely the disturbance storm-time index (Dst), the planetary geomagnetic activity index (Kp), and the solar flux (F10.7), are used to characterize the space weather conditions (SWC) that affect TEC anomalies and to identify the active/quiet days for future earthquakes. In this study, 13 different indices were used: indices that measured solar activity included proton flux (Pf) at six different energy levels, F10.7, and extreme ultraviolet (EUV0.1-50 nm and EUV26-34 nm). Meanwhile, geomagnetic storm indices included Dst, Kp, the z-component of the magnetic field index (Bz), and proton density (P-d). By using the ionospheric TEC values derived from global ionosphere maps (GIM-TEC), both negative and positive ionospheric TEC anomalies were observed for 15 days before and 4 days after the earthquakes using a statistical analysis technique that involved a 15-day moving median. The earthquakes were grouped according to their fault types (normal, thrust, and strike-slip) and focal depths (shallow, intermediate, and deep). Their relationships with the negative and positive TEC anomalies in the quiet days before the earthquake were examined. Negative and positive anomalies were observed approximately 3-12 days before earthquakes that occurred on normal faults, approximately 5-8 days before earthquakes that occurred on thrust faults, and approximately 1-12 days before earthquakes that occurred on strike-slip faults. The average TEC anomaly changes were calculated to be 43.4% total electron content unit (TECU) for normal faults, 44.8% TECU for thrust faults, and 41.3% TECU for strike-slip faults. Positive anomaly values were exhibited by larger earthquakes on normal and thrust faults, whereas negative anomaly values tended to occur on strike-slip faults. Negative and positive TEC anomalies were detected around 3-12 days before shallow earthquakes, around 1-13 days before intermediate-depth earthquakes, and around 1-12 days before deep earthquakes. The average TEC anomaly changes were calculated to be 44.4% TECU for shallow earthquakes, 43.3% TECU for intermediate-depth earthquakes, and 42.6% TECU for deep earthquakes. Positive anomaly values were also found to be higher than the negative anomaly values in each group. We propose that there is a relationship between the ionospheric TEC anomalies that occur before large earthquakes and their fault types and focal depths. (C) 2022 American Society of Civil Engineers.
- MakaleYayıncıda açık erişim2022Tectonic and structural characteristics of Erzurum and its surroundings (Eastern Turkey): a detailed comparison between different geophysical parameters
Özer, Çağlar; Öztürk, Serkan; Pamuk, Eren
The tectonic and structural properties of Erzurum and its surroundings have been investigated by evaluating the seismo-tectonic b-value, magnetic anomaly, edge detection analysis (total horizontal derivative (THDR) and tilt angle (TA)), Curie Point Depth (CPD), P-wave velocity (Vp), and Vp / Vs (S-wave velocity) ratio and by imaging the regional distributions of these parameters. For this purpose, all parameters have been combined to be able to reveal the new useful results on the study region and are presented for different locations and depths. The Vp values have been accompanied by high Vp / Vs ratios and shallow CPD values in the areas with geothermal regions such as Tekman, Söylemez, and the northern part of Karlıova. In the tectonically active regions such as Ilıca, Dumlu, Pasinler, Çat, Karlıova and Karaçoban, high reduction-to – the-pole (RTP) total magnetic anomaly was accompanied by low Vp values in harmony. Besides, the low Vp values between 0 and 10 km and high b-values can be related to the weakness zones and the areas in which earthquake hazards are high in the study area. The low Vp values in the 0 km horizontal slice are in accordance with the high RTP total magnetic anomaly values in the triangle area between Aşkale, Ilıca-Dumlu-Pasinler, Narman, and Karaçoban. Uniformly, high Vp and low RTP total magnetic anomaly inclusions overlap in Çat and Tekman. In some regions such as Dumlu, Narman, Horasan, Karaçoban and south of Karlıova, the tilt angle values are positive (positive values in the tilt angle map correspond to the center of the structure causing the magnetic anomaly) and the Vp values are low, but there is not a complete harmony between these parameters. These results show that variations on these parameters are related to each other, and these types of geophysical data are required for tectonic and structural features at different locations and depth levels.
- MakaleAçık Erişim2021A comprehensive spatiotemporal evaluation of the current earthquake activity in different parts of the Frakull-Durrës fault zone, Albania
Öztürk, Serkan; Ormeni, Rrapo
This study presents a detailed spatiotemporal analysis for the Frakull-Durrës (F-D) fault zone at the beginning of 2020. For this purpose, the most frequently used statistical seismicity parameters such as magnitude completeness, Mc-value, Gutenberg-Richter b-value, recurrence times, annual probabilities and standard normal deviate, Z-value, were mapped. The F-D fault zone was divided into two seismogenic subregions, and Mc-value was taken as 2.5 for both the south and north parts. The b-value was estimated as 0.83 ± 0.06 for the south part and 0.85 ± 0.06 for the north part. b-values for both zones are smaller than 1.0 and these values may be considered to be a larger stress accumulation to build up over time and to be released by the next possible earthquakes. Clear decreasing trends were observed in time variations of b-values before the occurrences of several strong main shocks. Analyses of annual probabilities and recurrence times suggest that the study region has an intermediate/long-term earthquake hazard in comparison to occurrences of strong/destructive earthquakes in the short term. Some anomaly regions of a small b-value and a large Z-value were found along the F-D fault zone at the beginning of 2020: i) among Lushnje-Tirana-Durrës including the middle part of the F-D fault zone, ii) in and around Lezha including the north end of the F-D fault zone. Thus, the combination of regions with the lowest b-value and largest Z-value may supply preliminary results for earthquake hazard, and these regions may be considered to be the most likely regions for future strong/large earthquakes in the F-D fault zone.
- MakaleAçık Erişim2021Statistical behaviours of earthquake occurrences in the Central Anatolian Region of Turkey: region-time-magnitude analyses
Öztürk, Serkan
The main objective of this work is to make detailed region-time-magnitude analyses by describ-ing the statistical behaviours of earthquakes in the Central Anatolian Region of Turkey. In this scope, several seismic and tectonic parameters such as Mcomp, b-value, Dc-value, Z-value, recurrence times and annual probabilities were evaluated. For the analyses, a homogeneous catalogue including 10,146 earthquakes with 1.0 ≤ Md ≤ 5.7 between 30 July 1975 and 29 December 2018 was used and spatio-temporal changes of earthquake behaviours were mapped for the beginning of 2019. Earthquake magnitudes varied from 1.9 to 3.0 on average, and hence Mcomp was considered to be 2.6. The b-value was calculated as 1.26 ± 0.07, and this relatively large value indicates that small-magnitude events are dominant. The Dc-value was computed as 1.31 ± 0.03. This small value means that distances between epicentres approach the diameter of the cluster, and seismic activity is more clustered at smaller scales or in larger regions. The spatio-temporal analyses of recurrence times suggest that the Central Anatolian Region has an intermediate/long-term earthquake hazard in comparison to occurrences of strong earthquakes in the short term. Several anomaly regions of a small b-value and a large Z-value were found in and around the Tuzgölü Fault Zone, Central Anatolian Fault Zone, Salanda fault and Niğde fault at the beginning of 2019. Thus, a combination of the regions with a lower b-value, a higher Z-value and also moderate recurrence times may give significant clues for the future possible earthquakes, and detected regions may be thought to be the most likely areas for strong/large events in the Central Anatolian Region.
- MakaleAçık Erişim2021Estimation of ground types in different districts of Gümüşhane province based on the ambient vibrations H/V measurements
Öztürk, Serkan; Beker, Yasemin; Sari, Mahmut; Pehlıvan, Levent
In this study, an attempt was made to estimate the ground types for Torul, Kürtün, Kelkit, Şiran and Köse districts of Gümüşhane, Turkey, by analyzing the predominant frequency and H/V ratio from microtremor data through the single station microtremor H/V ratio of Nakamura technique. For all districts, predominant frequencies show a general distribution between 1.36 and 9.84 Hz, H/V ratios between 1.01 and 9.58. According to these variations, three transient zones can be suggested as i) Z1, stiff rock composed of gravel, sand and other soils mainly consisting of tertiary or older layers with period of 0.1 to 0.2s, ii) Z2, sandy gravel, stiff sandy clay, loam or sandy alluvial deposits whose depths are 5m or greater with period of 0.2 to 0.4s, and iii) Z3, standard grounds other than type Z1, Z2 or Z4 (alluvial deposits whose depths are 5m or greater) with period of 0.4 to 0.8s. These r esults s uggest that p redominant period obtained from predominant frequency shows significant changes based on the soil formation, and H/V ratio highly corresponds to these subsurface properties. Soil-structure interaction can also be evaluated by considering these results and possible resonance risk can be investigated for building resonant frequency in these residential districts in the next. Thus, this type of application and evaluation of microtremor data may provide primary and useful information for other geophysical, geological and geotechnical studies such as planning the seismic resistant infrastructure, detecting the small-scale seismic risks and making a suitable and reliable seismic hazard microzonation in Gümüşhane. Copyright 2021, Yıldız Technical University.
- MakaleYalnız künye2020Analysis of ionospheric TEC anomalies for global earthquakes during 2000-2019 with respect to earthquake magnitude (Mw≥6.0)
Ulukavak, Mustafa; Yalçınkaya, Mualla; Kayıkçı, Emine Tanır; Öztürk, Serkan; Kandemir, Raif; Karslı, Hakan
In this work, a relationship between ionospheric TEC anomalies and different earthquake magnitude groups before the main shocks was investigated. For this purpose, 2942 global earthquakes with Mw≥6 from 2000 to 2019 and possible ionospheric TEC anomalies that occurred before earthquakes were examined by considering 13 different index values of space weather conditions (geomagnetic storm indices and solar activity indices). Anomalies of ionospheric TEC changes were defined for 15-days before and 4-days after the earthquakes by using 15-days moving median method with the length of 15 days. Earthquakes were first grouped according to their magnitudes, and then negative and positive TEC anomalies in quiet days before the earthquakes were detected. These anomalies were observed as ∼5–13, ∼5-10, ∼5-15, ∼3-13, ∼7-15, ∼1 and ∼5-8 days ago for the earthquakes of 6.0 ≤ Mw<6.5, 6.5 ≤ Mw<7.0, 7.0 ≤ Mw<7.5, 7.5 ≤ Mw<8.0, 8.0 ≤ Mw<8.5, 8.5 ≤ Mw<9.0, and 9.0 ≤ Mw<9.5, respectively. Mean of changes in TEC anomalies of these groups is 44.2 % TECU and we detected that the number of positive anomalies in each group is larger than the number of negative anomalies. Consequently, these analyses clearly show that the day-to-day changes in TEC anomalies may supply significant precursors prior to the global earthquakes (M ≥ 6) in the short-term earthquake prediction for main shocks.
- MakaleYalnız künye2020A GENERAL OVERVIEW ON THE REGION-TIME BEHAVIORS OF THE RECENT EARTHQUAKE ACTIVITY IN THE MARMARA REGION OF TURKEY
Öztürk, Serkan; Gerdan, Serpil
The principal aim of this study is to make a general assessment of the regional and temporal behaviors of the seismicity in the Marmara region of Turkey. For this purpose, the well-known spatio-temporal tools such as Mc-value, b-value, Dc-value, Z-value, recurrence period and annual probability were evaluated. The data catalog is homogeneous for local magnitude, ML, and includes 18,662 events with 0.4≤ML≤5.7 between 2000 and 2020. Earthquake magnitudes change between 1.5 and 3.0 and hence, Mc-value was taken as 2.7. b-value was calculated as 1.14±0.07 and the earthquakes with small magnitude can be effective on this relatively large value. Dc-value was estimated as 1.57±0.03 with a scale invariance from 5.03 to 87.64 km. This moderate value means that distance between the epicenters approaches the diameter of cluster and, earthquake activity is more clustered in larger areas or at smaller scales. Time-magnitude estimations of annual probability and recurrence period indicate that the Marmara region has an intermediate/long terms hazard for the occurrence of strong/large earthquakes. Anomaly regions with low b-value and large Z-value observed at the beginning of 2019 can be considered as the most likely regions for strong/large earthquake occurrences in the next. As a remarkable fact, a correlation and combined interpretation of these seismotectonic parameters may supply a preliminary and essential perspective in the seismic hazard for strong/large earthquake occurrences in the Marmara region of Turkey in the intermediate/long terms.
- MakaleAçık Erişim2020A comparison of alternative curve fitting techniques for different earthquake fault parameters of Iranian earthquakes; [Comparación de técnicas de ajuste de curvas para diferentes parámetros de fallas en terremotos en Irán]
Öztürk, Serkan; Ghassemi, Mohammad R.; Sarı, Mahmut
In this study, we tried to estimate the optimum linear equations among the parameters associated with different earthquake fault mechanisms for Iranian earthquakes. For this purpose, we tested different curve fitting methods in order to present the most proper empirical relationships between several seismic parameters for different fault systems. In the present paper, 46 large and destructive Iranian earthquakes whose magnitudes change between 5.8 and 7.8 from 1900 to 2014 were used for the analyses. A comparison was made by using four types of curve fitting techniques. The estimation procedures are considered as (1) L2 or Least Squares Regression, (2) L1 or Least Sum of Absolute Deviations Regression, (3) Robust Regression and, (4) Orthogonal Regression. Confidence intervals were selected as 95% for all types of regression relationships. In the selection of the best probability distribution, we considered the correlation coefficients of the linear regressions as a powerful and conceptually simple method. Correlation coefficients of all relationships change between 0.299 and 0.986 with Orthogonal regression, between 0.168 and 0.792 with L1 regression, between 0.059 and 0.829 with Robust regression. For Iranian earthquakes, the most suitable and reliable empirical relationships between moment magnitude (Mw) and surface wave magnitude (Ms), Mw and surface rupture length (SRL), Mw and maximum displacement (MD), and SRL and MD were obtained by Orthogonal regression since it supplies stronger correlation coefficients than those of the other regression techniques in most estimates. The results show that estimated empirical relationships among the different fault parameters by using the Orthogonal regression method can be accepted as more up-to-date and more appropriate in comparison with the other regression norms. Consequently, these equations were suggested as more reliable in the estimation of the maximum surface displacement, maximum surface rupture length and associated with the maximum credible earthquakes for different areas of Iran. Furthermore, obtained relationships can be statistically significant for the assessment of seismic, tectonic and geologic activities, and they can be used to evaluate the rupture hazard of the Iranian Plateau.
- MakaleAçık Erişim2019Region-Time-Magnitude Analyses of the Seismicity in and around the Central Anatolian Region and Current Earthquake Potential; [Orta Anadolu Bölgesi ve Civarındaki Depremselliğin Bölge-Zaman-Magnitüd Analizleri ve Güncel Deprem Potansiyeli]
Öztürk, Serkan
The purpose of this study is to make detailed statistical analyses of earthquake occurrences in and around the Central Anatolian Region of Turkey and to forecast the possible earthquake regions in the future. In this scope, by performing the region-time-magnitude analyses of seismotectonic variables such as Mc-value, b-value, Dc-value, Z-value, the current/future earthquake potential was defined. b-value was computed as 1.26±0.07 by taking Mc=2.6 and this large value indicates that the earthquakes with small magnitude are dominant. Dc-value was calculated as 1.31±0.03 and this relatively small value shows that distance between the epicenters approaches the diameter of cluster, and earthquake activity is more clustered in larger regions/at smaller scales. Anomaly regions with low b-value and large Z-value at the beginning of 2019 were found in and around Tuz Gölü Fault Zone, Central Anatolian Fault Zone, Salanda and Niğde faults. As an important result, these regions may be considered as the most likely regions for strong/large earthquakes in the future.
- MakaleYalnız künye2019A STUDY ON THE CHARACTERISTICS OF GÜMÜŞHANE SEISMICITY: ANALYSES OF REGION-TIME PARAMETERS
Öztürk, Serkan; Kaya, Aynur
The proposed study is focused on the identification of region-time characteristics of earthquakes in Gümüşhane, Turkey. Detailed statistical evaluations were achieved by considering the most frequently used size-scaling parameters such as seismotectonic b-value, fractal dimension Dc-value, standard normal deviate Z-value and recurrence time of earthquakes. Used earthquake catalog is homogeneous for duration magnitude, Md, and consists of 2902 shallow earthquakes with 1.0≤Md≤6.5 in about 47.76-years period between 1970 and middle of 2018. b-value is computed as 1.02±0.02 with a completeness level of 2.8, and this result indicates that frequency-magnitude distribution of seismicity in Gümüşhane is well represented with a b-value typically close to 1.0. Dc-value is calculated as 1.57±0.03 with a scale invariance between 4.96 and 86.28 km. This Dc-value means that seismic activity is more clustered in smaller areas or at larger scales in Gümüşhane. The analysis on the recurrence times of earthquakes implies that Gümüşhane has not a significant earthquake potential for the great earthquakes. Regional variation of b-value shows that small bvalues were observed in and around Kelkit and Köse, and these regions may have a possible earthquake hazard and risk in the future. Z-value analysis suggests that there are not noticeable seismicity rate changes in the mid-2018. These statistical results indicate that the seismic hazard is low and seismic risk is minor in the intermediate term in Gümüşhane.
- MakaleYalnız künye2019A statistical space-time-magnitude analysis on the aftershocks occurrence of the July 21th, 2017 M W = 6.5 Bodrum-Kos, Turkey, earthquake
Öztürk, Serkan; Şahin, Şakir
In this study, a detailed space-time-magnitude assessment on the aftershock sequence of July 21th, 2017, M W 6.5, Bodrum-Kos earthquake (Turkey) is carried out by focusing on the analyses of aftershock parameters: b-value, p-value, Dc-value and Mamax. b-value is estimated as 0.90 ± 0.05 with a completeness magnitude Mc = 1.6 and this relatively small b-value may be resulted from the abundance of aftershocks with magnitude M L ≥ 4.0. However, it is well represented by the Gutenberg-Richter law with a typically b ≈ 1.0. p-value is estimated as 1.04 ± 0.02 with a c-value = 0.224 ± 0.039 and is well characterized nearly close to the global p ≈ 1.0. This relatively high p-value may be a result of the relative fast decay rate of the aftershock activity. Dc-value is calculated as 1.74 ± 0.09 and it means that aftershocks are homogeneously distributed. Temporal distribution of b-value shows that small b-values may be due to a stepwise increase in effective stress before the occurrence of larger aftershocks. Regional changes range from 0.5 to 1.2 in b-value, from 0.4 to 1.3 in p-value and from 3.0 to 5.2 in Mamax. The smallest b-values are found in and around mainshock, including Karaada, Bodrum, Akyarlar and Turgutreis, and these regions have high stress as well as coseismic deformation. The largest p-values are found in and around the mainshock epicenter including Karaada, and it is interpreted that this situation may be caused by coseismic deformation. Mamax values larger than 4.4 are observed in and around mainshock epicenter, including Bodrum and Akyarlar, and there is a clear correlation between spatial variations of b-values and Mamax. These results show that stress changes and coseismic deformation seem highly effective on b and p-value variations. Therefore, a special interest needs to be given to these anomaly regions since aftershock hazard is highly associated with these parameters and may be developed considering their space-time-magnitude distribution.
- MakaleYalnız künye2018EMPIRICAL RELATIONS AMONG THE PARAMETERS ASSOCIATED WITH EARTHQUAKE RUPTURE MECHANISMS FOR IRANIAN EARTHQUAKES
Öztürk, Serkan; Ghassemi, Mohammad Reza; Sari, Mahmut
In this study, we aimed to derive the new and more reliable empirical relationships among different seismic parameters associated with the earthquake rupture mechanisms for Iranian earthquakes. For this purpose, we firstly converted the surface wave magnitudes into moment magnitudes in order to prepare a uniform earthquake dataset. Thereafter, we estimated the empirical relationships between moment magnitude and surface rupture length, moment magnitude and maximum displacement, and surface rupture length and maximum displacement. These linear empirical equations were obtained by orthogonal regression and the goodness of fits were discussed in terms of the correlation coefficients. The results obtained by the orthogonal regression in this paper are compared with the results obtained by the least square method in the literature. The present study confirms that representations of statistical correlations among different earthquake faulting parameters can be given more clear and straightforward by the orthogonal regression as compared to the least square method. In addition, such kind of relationships may provide some significant insights for the calculation of the maximum surface rupture length, maximum surface displacement, and associated maximum credible earthquakes for different seismotectonic regions of Iran as well as the estimation of earthquake magnitudes in paleoseismological studies.
- MakaleYalnız künye2018DETECTION OF THE COMPLEX GROUND PROBLEMS BY GROUND PENETRATING RADAR: EXAMPLES FROM GUMUSHANE UNIVERSITY
Sari, Mahmut; Öztürk, Serkan
In this study, Ground Penetrating Radar (GPR) technique was used for the detection of i) the reasons of deformations which occur in the field ground of Gumushane University Sport Complex (GUSC), and ii) the congestion in flow pipe of Gumushane University, Engineering and Natural Sciences Faculty (GUENSF). GPR data was collected by using the RAMAC CU II device and a shielded antenna with a 500 MHz center frequency. The wave fields for GUSC were examined by 2D and 3D processing. The large-scaled hyperbolic reflections are in corresponds to the areas where the field ground has deformations. It is considered that these anomaly areas may include a gap or a padding having a large gap and suggested that these damaged areas must be full with hard materials. The large-scaled hyperbolic reflections approximately starts in one-meter depth and reaches three-meters. For GUENSF, the measurements were conducted on the route where the main flow pipe crosses. In GPR sections, hyperbolas with high amplitudes were observed in the zones where flow pipe passes. Information on slope of flow pipe was provided by examining the association of these hyperbolas with the depth, and the clogged zones were detected. It is stated that unclogging the clogged zones of the flow pipe will not fully contribute to the resolution of the problem. Therefore, it is suggested to provide necessary slope to the flow pipe by completely removing and mounting back. These results show that GPR technique is an effective tool to provide a good image and solution for the complex ground problems.
- MakaleYalnız künye2017Gümüşhane ve Civarındaki Güncel Deprem Aktivitesinin Bölgesel ve Zamana Bağlı Değişimleri: İstatistiksel Bir Değerlendirme
Öztürk, Serkan
Bu çalışmada, Gümüşhane ve civarındaki deprem aktivitesinin bölgesel ve zamana bağlı değişimlerinin istatistiksel bir analizi yapılmış ve güncel deprem karakteristikleri tespit edilmeye çalışılmıştır. İstatistiksel analizler için, 21 Eylül 1970-26 Haziran 2016 yılları arasında süre magnitüdü MD>=1.1 olan ve 2500 depremi içeren yaklaşık 45.76 yıllık bir deprem kataloğu kullanılmıştır. Bununla birlikte, standart normal sapma Z-değerinin hesabı için MD?2.8 olan ve 1336 depremi içeren ayrıştırılmış deprem kataloğu kullanılmıştır. Deprem büyüklükleri genellikle 2.5-3.5 arasında değişim gösterirken MD=2.8 değerinde bir maksimuma ulaşmıştır. 2011 yılına kadar deprem sayılarında gözlenen sistematik artış 2011 yılından sonra bir azalım sürecine girmiştir. Çalışma alanı için tamlık magnitüdü Mc=2.8 olarak alınmış ve b-değeri 1.01±0.02 olarak hesaplanmıştır. Gümüşhane ve civarındaki depremlerin magnitüd-frekans dağılımı genel olarak b=1.0 ile verilen değerle iyi temsil edilir. 1970-2016 yılları arasındaki bölge için büyük sayılabilecek bazı depremlerden önce b-değerinde önemli düşüşler gözlenmekle birlikte son yıllarda önemli bir azalım gözlenmemiştir. Bölgesel ölçekte düşük b-değerleri, Kelkit ve Köse'yi içine alan doğu ve kuzey doğu kısımlar ile Köse'nin kuzeyinde ve Kelkit'in güneyinde gözlenmiştir. Düşük b-değerlerinin gözlendiği bu bölgeler gelecekteki olası deprem potansiyeli açısından önemli olabilir. Depremlerin tekrarlama zamanları ve yıllık olasılıkları üzerine yapılan analizler, Gümüşhane ve civarının büyük sayılabilecek deprem oluşumları açısından önemli bir deprem potansiyeline sahip olmadığını göstermektedir. Depremsellik oran değişimlerine bağlı olarak, 2016 yılı ortalarında herhangi bir sismik durgunluk anomalisi gözlenmemiştir. Sonuç olarak istatistiksel değerlendirmeler, Gümüşhane sınırları içerisinde kısa vadede önemli bir deprem tehlikesi potansiyelinin olmadığını ortaya koyar
- MakaleYalnız künye2017Regional and Temporal Analyses of the Current Earthquake Activity in and around the North Anatolian Fault Zone
Öztürk, Serkan
In this study, the regional and temporal variations of seismicity in and around the North Anatolian Fault Zone, one of the most seismically active strike slip fault systems in the World, are analyzed by using the seismotectonic b-value, fractal dimension Dcvalue, precursory seismic quiescence Z-value and correlations with each other. In order to produce an up-to-date and reliable statistical relation, several regression methods are tested. In and around the NAFZ, the relation of Dc=2.46-0.58*b having a very strong negative correlation coefficient, r=-0.98, is calculated as a more reliable relation. Significant fluctuations are observed in the temporal changes of b and Dc-values and the decreasing in b-value and thus the increasing trend in Dc-value between the years of 2012 and 2013 may be important in terms of the next earthquake potential in and around the NAFZ. The b-values lower than 1.0 and also the Dc-values larger than 1.85 are observed in the regions covering the vicinity of Düzce fault and the Black Sea coast, the vicinity of Pülümür fault and Erzincan, between Pülümür and Karlıova, Sancak-Uzunpınar and Göynük fault zones. At the beginning of 2016, seismic quiescence anomalies are observed in and around Enez, the north of Etili fault, Çanakkale and Edremit, Tekirdağ-Silivri and Marmara Sea, the part of Black Sea and the vicinity of Yalova-İzmit, the northern part of Manyas fault, İznik-Gebze, Düzce fault and the Black Sea coast, İsmetpaşa segment and Laçin-Merzifon fault zone. The regions having both the smallest b-value and the largest Dc-value with the high Z-value are the vicinity of Düzce fault and the Black Sea coast. As an important result, the combination of these seismotectonic parameters may supply some important evidences in order to reveal the next earthquake potential in and around the NAFZ and, these anomaly areas may be interpreted as the possible locations of the next earthquakes.
- MakaleYalnız künye2015Depremselliğin Fraktal Boyutu ve Beklenen Güçlü Depremlerin Orta Vadede Bölgesel Olarak Tahmini Üzerine Bir Modelleme: Doğu Anadolu Bölgesi, Türkiye
Öztürk, Serkan
Bu çalışma kapsamında, Doğu Anadolu bölgesi (Türkiye) için depremlerin oluş sürecindeki düzensizliklerinin bir ölçüsü olan fraktal boyut ile beklenen depremlerin orta vadede bölgesel olarak tahmini üzerine bir modelleme yapılmıştır. Bu amaçla, öncelikle Doğu Anadolu bölgesi depremleri için sismotektonik b-değeri ile fraktal boyut Dc-değeri arasında en uygun ve en güvenilir istatistiksel ilişki belirlenmeye çalışılmıştır. Bu uygulama için; (1) En Küçük Kareler Yöntemi (L2 Norm), (2) En Küçük Toplamlı Mutlak Sapma (L1 Norm), (3) Ortogonal Regresyon (Toplam En Küçük Kareler) ve (4) Robust Regresyon olmak üzere dört farklı regresyon yöntemi uygulanmıştır. Ayrıca, göreceli yoğunluk ve oluşum bilgisi haritalarının birleştirilmesi ile Doğu Anadolu bölgesinde beklenen güçlü depremlerin bölgesel olarak tahmini için birleşik tahmin haritası oluşturulmuştur. Analizler için kullanılan deprem kataloğu, Kandilli Rasathanesi ve Deprem Araştırma Enstitüsü'nden derlenmiştir. Katalog, süre magnitüdü MD için homojendir ve 1 Ocak 1970 ile 1 Ocak 2014 yılları arasında magnitüdü 1.0-6.6 arasında değişen 30462 depremi içermektedir. Birincil amaç olarak, Doğu Anadolu bölgesi için fraktal boyut Dc-değeri ve sismotektonik parametre b-değeri ile tanımlanan uzay, zaman ve magnitüd dağılımlarındaki fraktal bir yapıya sahip olan depremselliğin ortaya konması hedeflenmiştir. Bölgesel ölçekte detaylı bir değerlendirme yapabilmek için, Doğu Anadolu bölgesi 19 farklı sismotektonik alt bölgeye ayrılmıştır. İki sismotektonik parametre arasında daha güncel ve güvenilir bir istatistiksel ilişki hesaplayabilmek için, dört farklı regresyon kullanılmıştır. Her bir regresyon için, ilişki katsayıları ile birlikte aşağıdaki doğrusal ilişkiler elde edilmiştir: İkincil amaç olarak, Doğu Anadolu bölgesi için depremlerin yoğunluğuna ve oluşum bilgilerine dayalı bir birleşik deprem tahmin haritası oluşturulması hedeflenmiştir. Analiz için, 1970-2014 yılları arasında 40 km'den daha sığ ve kesme magnitüdü Mc>=3.4 olan depremler kullanılmıştır. Tahmin haritasının bölgesel görünümü için, 0.075? x 0.075?'lik bir bölgesel grid aralığı kullanılmış ve olası MD?5.0 olan depremler için bölgesel olarak bir tahmin yapılmaya çalışılmıştır. 1 Ocak 1970 ile 1 Ocak 2024 yılları arasında Doğu Anadolu bölgesinde beklenen güçlü depremlerin orta vadede bölgesel olarak tahmin edilebilmesi için birleşik tahmin haritası hazırlanmıştır. Analiz sonucunda, Doğu Anadolu bölgesinde bazı bölgeler gelecekteki deprem potansiyeli açısından tehlikeli bölgeler olarak belirlenmiştir. Bu bölgeler; Aşkale fayı ve civarı, Van Gölü'nün batısı (Süphan fayı ile Erciş fayı arası), Yüksekova-Şemdinli fay zonu civarı, Ovacık fayı civarında ve kuzey kesimleri, Doğu Anadolu fay zonu üzeri ve güney batı ucu, Kuzey Anadolu fay zonunun Muş Bindirme zonu ile Pülümür fayı arasında kalan kısmı. Sonuç olarak, anomalilerin gözlendiği bu bölgelere dikkat edilmesi ve deprem aktivitesinin takip edilerek diğer jeofizik yöntemlerle birlikte değerlendirilmesi önerilir.
- MakaleYayıncıda açık erişim2015A study on the correlations between seismotectonic b-value and Dc-value, and seismic quiescence Z-value in the western anatolian region of Turkey
Öztürk, Serkan
The Western Anatolian region is one of the most seismically active sectors of Turkey where small-magnitude events with considerable clustering occur frequently. The spatial and temporal behaviors of seismic activity as quantified by the fractal dimension Dc-value, seismotectonic b-value and seismic quiescence Z-value are investigated for the Western Anatolian region. For this purpose, a statistical relationship is developed between b and Dc-values, and regional and temporal changes of these parameters are analyzed in order to reveal the potential of future earthquakes in the study region. By using standard deviate Z-value, current seismicity rate changes are estimated in the beginning of 2014. The Western Anatolian region is divided into 18 different seismogenic subregions. Orthogonal regression fit is preferred in order to estimate more up-to-date and reliable statistical correlation between two seismotectonic parameters. The relationship of Dc=2.74-0.29*b is computed with a significant negative correlation (r = -0.73) between b and Dc-values for the Western Anatolian earthquake distributions. There are clear fluctuations in the temporal changes of these two parameters and the same results are relatively obtained in previous studies in literature. Lower b-values smaller than 1.0 and also higher Dc-value are observed in the Burdur fault zone and Kütahya graben. In addition, the regions in which the lower b-values and the higher Z-values are estimated cover the Burdur fault zone, Aliağa-Dumlupınar faults and Bakırçay grabens. Consequently, the relationships between seismic bvalue, fractal dimension Dc-value and seismic quiescence Z-value may provide important evidences to put forth the next earthquake potential in Western Anatolia. In addition, monitoring of microseismic activity and behaviors of some other geophysical parameters should be analyzed in space and time and evaluated carefully.
- Derleme MakaleYalnız künye2015Seismic b-Values, Bouguer Gravity and Heat Flow Data Beneath Eastern Anatolia, Turkey: Tectonic Implications
Maden, Nafiz; Öztürk, Serkan
In this paper, we analyze the relationships between the seismic b-values, Bouguer gravity and heat flow data in the Eastern Anatolia region of Turkey. For this purpose, spatial distributions of b-value, Bouguer gravity and heat flow have been presented for different depths and locations. In distinction to previous studies which have used only two parameters (gravity and seismic b-value or heat flow and seismic b-value), we have combined seismic b-values, Bouguer gravity and heat flow data to determine the new results on the active tectonics of the Eastern Anatolia region. Our analysis shows that there are significant and robust correlations amidst the heat flow data, Bouguer gravity anomaly and seismic b-values. The crustal structure is thick in areas where the large negative gravity anomalies and low b-values are observed. On the contrary, the regions with positive gravity anomalies and high b-values are likely to be associated with magma chambers or crustal low-velocity zones. We also provide some evidence suggesting that high b-values and high heat flow values can be related to the magmatic activities beneath the volcanic chain in the Eastern Pontide orogenic belt. Consequently, we have reached some conclusions for the Eastern Anatolia region: (1) The Moho to surface is rather thick and earthquakes are relatively smaller beneath the volcanic chain where the high heat flow values are observed, (2) a southward subduction model could have existed for the development of the Pontides during the late Mesozoic–Cenozoic era, (3) hot and unstable mantle lid zones or a lithosphere deprived of mantle under the study region is much more plausible, (4) a southward movement of the subduction plate and a northward extension of the Black Sea increase the state of stress along the trench axis and decrease the b-value, and (5) these movements may load the stress energy to the fault zones, thereby causing the catastrophic earthquakes in the Eastern Anatolia region.