Yazarlar
- Öztürk, Serkan(18)
- Alkan, Hamdi(8)
- Ormeni, Rrapo(5)
- Öztürk, S.(3)
- Hasimi, Albana(2)
- Ozturk, Serkan(2)
- Silo, Erald(2)
- Ahadov, Bahruz(1)
- Akkaya, İsmail(1)
- Bektaş, Özcan(1)
- Bozo, Rrezart(1)
- Büyüksaraç, Aydın(1)
- Como, Elvin(1)
- Fundo, Akli(1)
- Gerdan, Serpil(1)
- Güney, Recep(1)
- Hoxha, Ismail(1)
- Mucaj, Dionald(1)
- Pamuk, Eren(1)
- Rivza, B.(1)
- Salah, Mohamed K.(1)
- Trofymchuk, O.(1)
- Çomo, Ervin(1)
- Özer, Çağlar(1)
- çElik, Kemal(1)
- öZtürk, Serkan(1)
- Şimşek, Ecenur Cansu(1)
Yayınlar
- MakaleAçık Erişim2026Seismic potential in and around the Muş basin (Eastern Türkiye): Insights from stress analysis and statistical modeling; [Muş havzası (Doğu Türkiye) ve civarındaki deprem potansiyeli: Gerilme analizi ve istatistiksel modellemeden elde edilen çıkarımlar]
Şimşek, Ecenur Cansu; Alkan, Hamdi; Öztürk, Serkan
In this research, current and near-future potential earthquake zones in and around Muş basin (eastern Türkiye) are investigated using the instrumental period earthquake catalog and focal mechanism parameters of local earthquakes. For this purpose, the relationships between the b-value distributions and the Colulomb stress changes are interpreted with different depth ranges (5 to 25 km). Also, for a reliable prediction, the occurrence probabilities, recurrence periods of earthquakes, and the Z-value distribution (seismic quiescence areas) are taken into consideration. 15,722 earthquakes with moment magnitudes with 0.8≤Mw≤6.9 between the latitudes of 38.2°N-39.6°N and longitudes of 40.0°E-43.0°E, over a period of ~90.63 years between November 12, 1934, and June 30, 2025, are used for all statistical analyses. Completeness magnitude, Mc-value is accepted as 2.5±0.5. The b-value is determined to be 0.780 ± 0.04, which is smaller than the average (b = 1.0). Additionally, twenty local events with magnitudes greater than Mw≥4.8 are selected to image the Coulomb stress changes. The occurrence probabilities of earthquakes with Mw=5.5, 6.5, and 6.9 in 10 years are predicted as ~83%, ~27% and ~15%, respectively. Recurrence periods of events with these magnitudes are estimated as ~13, ~32, and ~63 years, respectively. Large Z-values are detected in the Kargapazarı segment, Bingöl province, and west of the Kulp and Kozluk segments. Additionally, the analyses of b-value and Coulomb stress change used for hazard prediction reveal a decreasing b-value and an increasing stress change around the Karlıova Triple Junction at a depth of approximately 10 km. Finally, these seismotectonic parameters can represent the possible locations for earthquake occurrences in the near future.
- MakaleYalnız künye2026Tomography of the source zone of the February 6, 2023, Kahramanmaras, Earthquake Doublets of Southern Anatolia
Salah, Mohamed K.; Alkan, Hamdi; Öztürk, Serkan; Güney, Recep
On February 6, 2023, two destructive earthquakes and many posterior aftershocks hit the Kahramanmaras,area in southern Anatolia. The Kahramanmaras, earthquake sequence (KMES) caused extensive damage and economic losses in T & uuml;rkiye and Syria. In this study, the 3-D crustal seismic velocities surrounding the hypocentral region of the KMES are determined using a large dataset of body wave arrival times obtained from local earthquakes. To better constrain the physical properties and seismogenic behavior of the KMES source region, the Vp/Vs ratio is calculated and correlated with Poisson's ratio using the obtained velocity models. To gain a better understanding of the stress conditions and regional earthquake activity in the study area, the depth variation of the b-value is also examined. The velocity structure is generally heterogeneous with both low and high velocities at upper crustal depths. Along the East Anatolian Fault Zone and its environs, low-velocity anomalies are charted. Also, small b-values (<1.0) are estimated in the region encompassing the KMES, especially at upper crustal depths. The KMES source zone is characterized by low b-value, low to average Vp, low Vs, and average/high Vp/Vs ratios. Hit count rates and the resolution test show that the mapped velocity anomalies are robust down to a depth of 45 km. Therefore, the moderate/high Vp/Vs and small b-values at the upper and middle crustal depths along the EAFZ may give constraints on the next earthquake hazards of the study region. The present findings provide deeper insight into the physical properties and the seismogenic potential of the crustal zones in proximity to the active fault segments of the Anatolian Plateau and the northwestern part of Arabia.
- MakaleAçık Erişim2025Spatial and temporal analysis of seismicity and seismotectonic parameters in Albania region
Ormeni, Rrapo; Öztürk, Serkan; Silo, Erald; Bozo, Rrezart; Hoxha, Ismail; Mucaj, Dionald
A comprehensive analysis of b-value for the Albanian earthquakes was conducted using the instrumental earthquake catalogue of Albanian region. A total of 38,816 seismic events with magnitudes ML> 0.1 on the Richter scale were utilized. Statistical characteristics of the seismicity were examined based on b-value, as defined by the Gutenberg-Richter law. Considering the magnitude completeness (Mc-value) as 2.7, b-value was estimated as 1.09 ± 0.08 and it indicates a normal stress regime in the region. The Mc-value varies from 1.5 to 3.4, and spatial distribution of b-value ranges from 0.79 to 1.16. Higher b-values (> 1.0) were detected in the southernmost part of Albania, whereas lower b-values (< 1.0) were found in the western part, particularly within the Adriatic-Ionian fault zone and the Lushnje-Elbasan-Dibër transversal fault zone, as well as in the south-eastern Leskovik-Erseka-Korça fault zone. Regions with lower b-values correspond to areas with larger-magnitude events, while higher b-values are associated with smaller earthquakes. These findings suggest that b-values across Albania generally round 1.0, with lower values indicating moderate stress accumulation in the western region and within two other active seismic belts. The b-values less than 1.0 may signal areas of increased seismic potential. The occurrence probability of earthquakes across varying magnitudes was found to be very high (99%-100%) for seismic events with ML between 0.5 and 4.5, and lower (less than 95%) for events with ML > 5.5; it varied from 1% to 60% for events with larger ML > 6.0 for different Tr values. Recurrence periods for smaller magnitudes are relatively short (less than 1 year for magnitudes from 1.0 to 4.2), whereas for larger magnitudes (5.0 to 6.0), recurrence periods are longer, about 100 years. The Albanian region is characterized by a complex geological setting and significant seismic activity, and, thus, it can be stated that these types of analyses may be important in terms of seismotectonic evaluation and seismic hazard.
- MakaleAçık Erişim2025September 25, 2024 Yumrukaya-Tatvan (Bitlis, Türkiye) earthquake and a seismo-tectonic evaluation of its impact on the earthquake hazard in the region; [25 Eylül 2024 Yumrukaya-Tatvan (Bitlis, Türkiye) depremi ve bölgedeki deprem tehlikesine etkisi üzerine sismo-tektonik bir değerlendirme]
Öztürk, Serkan; Alkan, Hamdi
The current and future earthquake hazard in and around Bitlis were tired to reveal by utilizing the September 25, 2024, Yumrukaya-Tatvan earthquake (Mw=4.5) and its aftershocks, b-value and Z-value distributions, occurrence probabilities and recurrence periods of earthquakes and variations in Coulomb stress within the scope of this study. Also, it was tried to determine which fault systems in the study area is related to the Yumrukaya-Tatvan mainshock, characterized by strike-slip faulting. b-value in G-R relation was computed as 0.84∓0.06 and small b-values (<1.0) were imaged in the north-northwest-southeast directions throughout the South East Anatolian Thrust Zone and Muş Fault Zone, and west of Lake Van. At the beginning of 2025, significant seismic quiescence was observed near the Muş Fault Zone and the south and southeast of the South East Anatolian Thrust Zone. Recurrence periods for the events with the magnitudes of Mw=5.0, 5.5 and 6.2 were computed as ~10, ~26 and ~100 years, respectively. Additionally, occurrence probabilities of earthquakes with these magnitudes in the intermediate-term (~10 years) were calculated as ~64%, ~32% and ~10%, respectively. Positive Coulomb stress changes carry out a movement from the Kavakbaşı Fault zone in the west and the Beğendik segment in the east toward the South East Anatolian Thrust Zone in the east-southeast. In this region, there is no active fault/fault system according to the General Directorate of Mineral Research and Exploration. Thus, these findings are significant clues showing that multiple parameter seismo-tectonic analyses are important in determining the earthquake hazard for the September 25, 2024 earthquake, and that regions with small b-values and seismic quiescence and regions with positive Coulomb stress changes may indicate current hazard and possible earthquake zones in the future.
- MakaleYayıncıda açık erişim2025Statistical and seismotectonic analyses of the Marmara region under existing stress regime in the west of the NAFZ
Alkan, Hamdi; Öztürk, Serkan; Bektaş, Özcan; Büyüksaraç, Aydın
The Marmara Region is an active tectonic region in northwestern Türkiye, which comprises some important strike-slip active fault mechanisms and important tectonic units, located near the western part of the North Anatolian Fault Zone. In the historical and instrumental period, the Marmara Region experienced large/devastating earthquakes. Considering this continuous activity, in this study, we investigate the tectonic structure and performed future seismic hazard estimation of the region based on some seismotectonic parameters. For this evaluation, we plot the Coulomb stress change maps of 1912 Mürefte-Şarköy, 1953 Yenice-Gönen and 1999 İzmit mainshocks with the earthquakes (MW ≥ 4.5) that occurred in the study region after 2003. For the estimation of b-value, occurrence probabilities and return periods of earthquakes, we used a homogenous local seismicity catalogue consisting of 119.029 events for the period between 1912 and 2023. In the findings of this study, the lower b-values and increasing Coulomb stress changes which are trigger stress failure compatible are observed in the west and northwest of the Marmara Sea. In contrast, the higher/moderate b-values and decreasing Coulomb stress values are observed in the east and southeast of the Marmara Sea. The results of probability assessments show that an earthquake with Mw = 6.5 may occur with a probability of 98% in the west of the Marmara Sea after 2025. As a remarkable fact, a comprehensive assessment of these types of variables will supply important findings for earthquake hazard and potential in the study region.
- MakaleAçık Erişim2024An evaluation of the earthquake potential with seismic and tectonic variables for the West Anatolian region of Türkiye
Öztürk, Serkan; Alkan, Hamdi
In the present study, an evaluation of the region-time-magnitude behaviours of the earthquake occurrences in the West Anatolian Region (WAR), Türkiye, is carried out using the statistical and seis-motectonic parameters such as the b-value of Gutenberg-Richter relation, occurrence probabilities, and return periods of earthquakes. We also have mapped the Coulomb stress changes to observe the current and future earthquake hazard. In recent years, several large earthquakes such as the 1919 Soma (Mw = 6.7) and the 2022 and 2024 Aegean Sea (Mw = 5.3 and Mw = 5.1) revealed earthquake potential in the WAR. Coulomb stress analyses of 41 local events with mostly normal fault mechanisms have shown that posi-tive lobes (> 0.0 in bars) are mainly confined in the crust and uppermost mantle depths around Samos, Kos, and south of Lesvos. The smaller b-values (< 1.0) are observed in the same regions. On the contrary, we have observed a higher b-value from the offshore to onshore, south to north-trending direction, and negative scattered stress lobes (< 0.0 in bars) in slightly NW–SE oriented. The relationship between an increased b-value and negative stress change may indicate a similar seismicity for the region. In addition, we have analyzed the occurrence probabilities and return periods of the earthquakes, which showed us that Mw = 6.0 may occur at 75% in the intermediate term with an estimation of ~7 years. Our results reflect that these types of multiple-parameter assessments are important to define regional seismicity, seismic, tectonic, and statistical behaviours. Consequently, the areas with reductions in b-values and increments in stress imply the possible seismic hazard in the intermediate/long term.
- MakaleAçık Erişim2023Correlations between seismic b-value and heat flow density in Vlora-Lushnja-Elbasani-Dibra Fault Zone in Elbasani area, central Albania
Ormeni, Rrapo; Hasimi, Albana; Öztürk, Serkan; Çomo, Ervin
In this study, the correlations between the heat flow density and seismotectonic b-value in the El-basani area of Albania were investigated to understand the how low-velocity layers underneath the Elbasani area in central Albania struggling the large-scale Vlora-Lushnja-Elbasani-Dibra Fault Zone affect the heat flow data. For this purpose, the heat flow and regional distribution of b-value were imaged for different locations and depths. To achieve the analysis, the Albanian Seismological Catalogue for the period between 1 July 1968 and 26 December 2022, including 1830 earthquakes with a local magnitude of 0.5 ≤ Ml ≤ 5.2 that occurred at the depths below 70 kilometres, was considered. The b-value was calculated as 1.03 ± 0.06 by considering the magnitude of the completeness value as Mc-value = 2.6. This result shows that the b-value of earthquake distribution in the Vlora-Lushnja-Elbasani-Dibra (VLED) fault zone is well represented by the Gutenberg and Richter (G-R) scaling law with the b-value close to 1.0. The regional variations of the b-value show that b-values smaller than 0.9 were observed in the western and south-western parts of the Llinxha-Kozan thermal water belt. The depth distribution of the b-value indicates that there exists a sharp decrease in the b-values from 1.15 to 0.7 in the depths varying from 5 to 20 km. The highest heat flow values were observed on the Dumrea diapiric dome and in the central part of the Elbasani area. Thus, our analysis indicates significant and robust correlations between the geothermal and earthquake distribution. The discontinuity of Moho interface is deep in the regions where high b-values were observed. Low b-values are found at the depths ranging from 20–25 km and 35–40 km in the Dumrea evaporite massif area. We have evidence that high b-values and large heat flow values are related to the low seismic velocity layers underneath the Elbasani area. The low-velocity zone (LVZ) in Albania occurs in the Earth’s crust and in the upper mantle. It is characterized by an unusu-ally low seismic shear wave velocity compared to the surrounding depth intervals. It is well known that the low-velocity layers in the Elbasani area are determined in the upper crust, at shallow depths of 2–4 km, and in the middle crust at a 10–14 km depth. Hence, it is suggested that the Moho interface in the eastern part of the Elbasani area is relatively deep (45 km) compared to the western part of Albania (35 km), and the magnitude of earthquakes is smaller where the high heat flow values were observed.
- MakaleAçık Erişim2023Multiple parameter analysis for assessing and forecasting earthquake hazards in the Lake Van region, Turkey
Öztürk, Serkan; Alkan, Hamdi
A detailed spatial-temporal analysis of the seismic activity in and around the Lake Van region was performed using several seismotectonic parameters such as b-value, Z-value, relative intensity (RI), pattern informatics (PI), and Coulomb stress changes. Correlations between these parameters were analyzed to esti-mate and forecast potential seismic hazards in the Lake Van region. Particular attention was paid to the parts of the study region that exhibited smaller b-values, higher Z-values, and high-stress changes at the beginning of 2022 and to the locations of earthquake hotspots determined from the composite earthquake forecast map for 2022–2032, i.e., Muradiye, Çaldıran, Özalp, Erçek, Van city center and Gevaş covering the faults of Çaldıran, Yeniköşk, Erciş, Malazgirt and the fault zones of Saray and Van. To provide more accurate interpretations regarding potential earthquake occurrences in the near future, the seismotectonic parameters analyzed in the scope of this study were compared with the corresponding seismological, geological, geodetical, and geochemical variables reported in the literature. This comparison showed that, firstly, our results are consistent with those reported in previous studies, and, secondly, all these variables should be interpreted in combination to correctly assess strong earthquake hazards. Furthermore, this type of multiple-parameter analysis may be important for the description of seismic, tectonic, and structural characteristics of the nature of the crust. Our findings show that almost all seismotectonic parameters indicative of anomaly regions, i.e., lower b-values, higher Z-values, high-stress distribution, and hotspots, were recorded in the same parts of the study region. Thus, the anomaly regions detected at the beginning of 2019 and between 2022 and 2032 may be considered to be potential zones of future great earthquakes. To summarize, the correlations among these variables may provide accurate information for assessing and forecasting earthquake hazards in this region.
- BildiriYalnız künye2023REGION-TIME-MAGNITUDE ANALYSES OF EARTHQAUKE ACTIVITY IN THE ELBASANI GEOTERMAL ZONE, ALBANIA
Ormeni, Rrapo; Öztürk, Serkan; Hasimi, Albana; Silo, Erald; Como, Elvin; Trofymchuk, O.; Rivza, B.
A detailed analysis of the b-value within the Elbasani fault zone, Albania, were studied. From instrumental seismicity in this area have been located 1830 seismic events, with magnitude Ml>0.5 Richter. In the zone of Elbasani, hot mineral water (thermal waters) spot out from natural springs which have been known since the 19th century. The statistical properties of seismicity are analysed by using b-value known as Gutenberg-Richter law. The magnitude of completeness (Mc) value is determined as 2.6, and the bvalue is calculated as 1.03 ± 0.06, and it is determined that the region has a normal stress level. It is seen that the Mc-value varies from 1.6 to 2.9, the b-value changes between 0.9 and 1.3. The regions with the large b-values (> 1.0) are estimated in the eastern parts of the of Elbasani zone. However, the regions with the low b-values (< 1.0) are observed in the north, west and southwest of Elbasani zone. The regions with the small b-values correspond to great-magnitude events, whereas the other large values are related to smallmagnitude earthquakes. These results reveal that b-values for all regions are well represented by a b-value typically close to 1.0. There are clear decreasing trends in temporal changes of b-values before the occurrences of some strong main shocks. The lower b-value indicate that there is still moderate stress accumulation in the southwest area of the Llinxha-Kozan thermal water belt. The b-values smaller than 1.0 indicate potential future earthquake area. Following the strong events, there are remarkable decreases in b-value as a function of time. Changes in b-value with time varies in a large band between 0.6 and 1.4. Probabilities of earthquake activity in different magnitude sizes show comparatively great values changing from 50-100 % for earthquakes of 0.5 ≤ Ml≤ 4.5 and the values relatively lower than 90 % for the earthquakes of 5.0 ≤ Ml. The Elbasani zone has a complex geological structure with a significant number of geothermal water resources and some features of seismicity.
- MakaleAçık Erişim2023An evaluation of the characteristic aftershock parameters following the 24 January 2020 MW = 6.8 Elazığ-Sivrice (Türkiye) earthquake
Öztürk, Serkan
A comprehensive evaluation of region-time-magnitude behaviours of aftershocks following the 24 January 2020 (Mw = 6.8) Elazığ-Sivrice (Türkiye) earthquake was achieved by using the characteristic parameters such as b-value, p-value, Dc-value and Mamax value of aftershock occurrences. The b-value was calculated as 0.82 ± 0.02 by considering the magnitude of the completeness value as Mcomp = 1.9, and it is relatively small compared to typical b ≈ 1 for the magnitude-frequency relationship of aftershocks. This low b-value may also be caused by the abundance of aftershocks with ML ≥ 4.0. The p-value was computed as 0.80 ± 0.02 with c-value = 0.279 ± 0.098 and is smaller than the global value of p ≈ 1. This low p-value may be due to a relatively slow decay rate of aftershock activity, and the modified Omori model seems appropriate for the estimation of decay parameters. The Dc-value was estimated as 1.87 ± 0.07. This large value shows that aftershocks are homogeneously distributed and more clustered at larger scales/in smaller areas. The temporal variation of b-value indicates that decreases in b-value may result from the gradual increase in the effective stress following the larger aftershocks. The lowest b-values and Mamax values greater than 5.0 were observed in the north, south and southwest parts of the mainshock including Pütürge and Erkenek segments. These results show that there is an apparent relation between the smallest b-values and the largest Mamax values. The largest p-values were estimated in and around the main shock including Pütürge segment. The regions with the smallest b-value and the largest p-value have high stress and coseismic deformation, respectively. Stress variations and coseismic deformation are extremely effective on the changes of b-and p-values. As a remarkable result, aftershock hazard following the mainshock may be considered extremely related to aftershock parameters, and detailed analyses of the region-time-magnitude characteristics of aftershocks are recommended for a preliminary evaluation following the mainshock.
- MakaleYalnız künye2023Seismic Hazard Implications in and Around the Yedisu Seismic Gap (Eastern Türkiye) Based on Coulomb Stress Changes, b-Values, and S-wave Velocity
Alkan, Hamdi; Öztürk, Serkan; Akkaya, İsmail
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.
- 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 Erişim2022A Statistical Analysis and Evaluation on the Earthquake Forecasting and Hazard for Lake Van and its adjacent area (Türkiye); [Van Gölü ve Civarı (Türkiye) İçin Deprem Tahmini ve Tehlikesi Üzerine İstatistiksel Bir Analiz ve Değerlendirme]
Ozturk, Serkan; Alkan, Hamdi
In this study, current earthquake hazard is tried to present and earthquake forecasting is made for Lake Van and its adjacent area for the next five years. For this purpose, a statistical analysis is achieved with the concomitant use of the b-value, Z-value, relative intensity (RI) and pattern informatics (PI) data. In addition, for the earthquake forecasting in the intermediate term and hazard, a comprehensive discussion is made with the studies analyzing the different seismological and geophysical variables in literature. The relations between these parameters reveal more accurate and reliable approaches. Consequently, at the beginning of 2022, particularly the areas having small b-value and large Z-value with the hotspots (possible earthquake areas) between 2022 and 2027 from the combined forecast map are determined in and around Muradiye, Çaldıran, Özalp, Van city centre and Gevaş including Çaldıran, Yeniköşk, Erciş and Malazgirt faults with Saray and Van Fault zones.
- Derleme MakaleYayıncıda açık erişim2022Spatial variations of fundamental seismotectonic parameters for the earthquake occurrences in the Eastern Mediterranean and Caucasus
Ahadov, Bahruz; Ozturk, Serkan
In this study, a comprehensive statistical analysis was made for different parts of the world. For this purpose, fundamental seismotectonic earthquake parameters such as b-value, magnitude completeness, Mc-value stress distribution and moment release were analysed and their interrelationship was investigated. In this context, for the evaluation of earthquake hazard potential, spatial variations of these fundamental parameters were achieved for the Eastern Mediterranean and Caucasus since there do not exist detailed studies including these parameters for these regions of the world. The high-resolution maps of the b-value, Mc-value and stress variance were analysed in the different seismotectonic regions in the Eastern Mediterranean and Caucasus. This study considers the spatial anomalies and correlation models between the b-value, faulting styles, and stress regime and moment release. Lower b-values (b ≤ 1) were observed along with the Main Marmara Fault, eastern Turkey, western Alborz, northern Zagros, south-east Iran and the north-east Caucasus, and these small b-values indicate the active seismic region. Mc level in most of Turkey is in and around 2.8. However, Mc-value is about 3.0 in the Caucasus and about 3.5 level in Iran. This work also includes a stress inversion map in the region based on the focal mechanisms. The normal, strike-slip and a few thrust fault solutions were observed in the research areas. The results show that a combination of these parameters may supply preliminary tools for future researches. Consequently, the spatial pattern of the b-values, moment releases and stress regimes can be used as considerable promise for the predicting of forthcoming seismic hazard regions.
- 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.
- 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.
- MakaleYalnız künye2020A study on the variations of recent seismicity in and around the Central Anatolian region of Turkey
Öztürk, S.
Variations of the recent seismicity in and around the Central Anatolian region of Turkey were evaluated based on the seismic b-value, standard normal deviate Z-value, GENAS modelling, annual probabilities and return periods of the earthquakes. The catalog includes 16,702 earthquakes between 1974 and 2019 with magnitudes from 1.0 to 6.3. Time distribution of b-value shows that there is a tendency to decrease after the year of 2002 and b-value decreased from 1.58 ± 0.03 to 1.25 ± 0.05 at the beginning of 2019. Annual probabilities for magnitude ranges of 3.0–4.0 have the values between 3 and 30. Return periods for magnitude levels of 5.0–5.5 have the values from 5 to 20 years, and a value of 80 years for magnitude level of 6.0. The GENAS results show the significant temporal variations in the number of earthquakes smaller and larger than specific magnitude intervals by supplying the beginning periods of increases and decreases in the earthquake activity rate. Remarkable reductions in region-time distribution of b-value at the beginning of 2019 were detected in the regions covering Niğde fault and its vicinity along the south, west, northwest and southwest directions, among the Mut Fault Zone, Karsantı-Karaisalı Fault Zone and Karataş-Osmaniye Fault Zone, in and around Sürgü fault and along its northwest direction, between Sürgü fault and East Anatolian Fault Zone. Significant seismic quiescence areas in Z-value distribution include the northwest ends of the Tuzgölü Fault Zone and study area including Akpınar fault, the northeast of Salanda fault, between Salanda fault and the Central Anatolian Fault Zone, the northeast parts of the Central Anatolian Fault Zone, the west of Malatya fault, between Sürgü fault and the East Anatolian Fault Zone, the southeast end of the Tuzgölü Fault Zone, Karsantı-Karaisalı Fault Zone and its vicinity, the southwest of Tuzgölü. Thus, these anomaly areas observed in the Central Anatolian region and its vicinity at the beginning of 2019 may be one of the most likely zones for the next strong/large earthquake occurrences.
- 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 künye2018Earthquake hazard potential in the Eastern Anatolian Region of Turkey: seismotectonic b and Dc-values and precursory quiescence Z-value
Öztürk, S.
The Eastern Anatolian Region of Turkey is one of the most seismically and tectonically active regions due to the frequent occurrence of earthquakes. Thus, the main goal of this study is to analyze the regional and temporal characteristics of seismicity in the Eastern Anatolia in terms of the seismotectonic b-value, fractal dimension Dc-value, precursory seismic quiescence Z-value, and their interrelationships. This study also seeks to obtain a reliable empirical relation between b and Dc-values and to evaluate the temporal changes of these parameters as they relate to the earthquake potential of the region. A more up-to-date relation of Dc = 2:55–0:39*b is found with a very strong negative correlation coefficient (r =–0.95) by using the orthogonal regression method. The b-values less than 1.0 and the Dc-values greater than 2.2 are observed in the Northeast Anatolian Fault Zone, Aşkale, Erzurum, Iğdır and Çaldıran Faults, Doğubeyazıt Fault Zone, around the Genç Fault, the western part of the Bitlis-Zagros Thrust Zone, Pülümür and Karakoçan Faults, and the Sancak- Uzunpınar Fault Zone. In addition, the regions having small b-values and large Z-values are calculated around the Genç, Pülümür and Karakoçan Faults as well as the Sancak-Uzunpınar Fault Zone. Remarkably, the combinations of these seismotectonic parameters could reveal the earthquake hazard potential in the Eastern Anatolian Region of Turkey, thus creating an increased interest in these anomaly regions.