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- 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.
- 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 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.