Yazar "Alkan, Hamdi" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • [ X ]
    Öğe
    6 Şubat 2023 Kahramanmaraş merkezli depremler sonrasında Muş ili ve çevresinin deprem tehlikesine yönelik bir değerlendirme
    (2023) Dölek, İskender; Ekinci, Rezzan; Alkan, Hamdi; Büyüksaraç, Aydın; Ekinci, Yunus Levent
    Türkiye’nin doğusunda bulunan Muş havzası birçok aktif fay ve fay zonuna sahiptir. Ayrıca bölge tarihsel ve aletsel dönemde yıkıcı etkiye sahip orta ve büyük birçok depreme maruz kalmıştır. Bu çalışmada, Muş havzasında 2010-2023 yılları arasında meydana gelen ve büyüklükleri Mw?4.0 olan depremler kullanılarak bölgenin tektonik gerilme durumu Coulomb gerilme analizi ile incelenmiştir. Derinlik ile birlikte statik gerilme değişimlerini modellemek için farklı derinlik seviyeleri içim Coulomb gerilme değişimi haritaları oluşturulmuştur. Özellikle, Muş havzasının kuzey batısında bulunan Karlıova üçlü birleşimi civarında bulunan Kuzey Anadolu Fay Zonu ile ilişkili Kargapazarı ve Elmalı segmentleri ile Varto Fay Zonu boyunca sığ derinliklerde pozitif Coulomb gerilme değerleri göze çarpmaktadır. Bunun aksine, Muş şehir merkezinin doğusunda bulunan Bulanık Fayı, Haçlıgölü Fayı ve Malazgirt Fayı civarında ise gerilme değişiminin daha durağan olduğu gözlenmiştir. Sonuç olarak, Muş şehir merkezinin özellikle kuzey doğusunda sığ derinliklerde sismik aktivite ihtimali diğer bölgelere göre daha yüksektir.
  • [ X ]
    Öğe
    Comparison of Seismic and Structural Parameters of Settlements in the East Anatolian Fault Zone in Light of the 6 February Kahramanmaraş Earthquakes
    (Mdpi, 2024) Isik, Ercan; Hadzima-Nyarko, Marijana; Avcil, Fatih; Buyuksarac, Aydin; Arkan, Enes; Alkan, Hamdi; Harirchian, Ehsan
    On 6 February 2023, two very large destructive earthquakes occurred in the East Anatolian Fault Zone (EAFZ), one of T & uuml;rkiye's primary tectonic members. The fact that these earthquakes occurred on the same day and in the same region increased the extent of the destruction. Within the scope of this study, twenty different settlements affected by earthquakes and located directly on the EAFZ were taken into consideration. Significant destruction and structural failure at different levels were induced in reinforced concrete (RC) structures, the dominant urban building stock in these regions. To determine whether the earthquake hazard is adequately represented, the PGA values predicted in the last two earthquake hazard maps used in T & uuml;rkiye for these settlements were compared with the measured PGAs from actual earthquakes. Subsequently, the damage to reinforced concrete structures in these settlements was evaluated within the scope of construction and earthquake engineering. In the final part of the study, static pushover analyses were performed on a selected example of a reinforced concrete building model, and target displacement values for different performance levels were determined separately for each earthquake. For the 20 different settlements considered, the displacements were also derived based on the values predicted in the last two earthquake hazard maps, and comparisons were made. While the target displacements were exceeded in some settlements, there was no exceedance in the other settlements. The realistic presentation of earthquake hazards will enable the mentioned displacements predicted for different performance levels of structures to be determined in a much more realistic manner. As a result, the performance grades predicted for the structures will be estimated more accurately.
  • [ X ]
    Öğe
    Coulomb Stress Analysis in Nemrut Caldera (East Anatolia, Türkiye)
    (2024) Alkan, Hamdi; Bektaş, Özcan; Büyüksaraç, Aydın
    In volcanic areas, seismic events with low energy occur before seismic activity or due to the movement observed in the magma. These earthquakes, which are caused by the expansion-contraction movement that has been revealed in different studies and is mostly observed in the magma chamber, can be recorded with continuous observations. On the other hand, it is not easy to distinguish between tectonic and volcanic origins of earthquakes occurring in volcanic areas. In this study, Coulomb stress analysis was carried out using earthquakes in the Nemrut Stratovolcano, which is located in the eastern Türkiye and is at the westernmost end of a volcano arc, and it was concluded that the stress is related to the Nemrut Caldera, therefore the positive stress caused by the expansion of the magma chamber of the Nemrut Volcano creates tremors.
  • [ X ]
    Öğe
    Fault modeling around southern Anatolia using the aftershock sequence of the Kahramanmaras earthquakes (Mw=7.7 and Mw=7.6) and an interpretation of potential field data
    (Springer Int Publ Ag, 2024) Buyuksarac, Aydin; Bektas, Ozcan; Alkan, Hamdi
    On February 6, 2023, southeastern Turkiye experienced devastating doublet earthquakes (Mw = 7.7 and Mw = 7.6) with a series of aftershocks along the East Anatolian Fault Zone. The mainshocks were followed by similar to 15,000 aftershocks mainly distributed in the NNE-SSW direction, including similar to 400 events with an Mw >= 4.0 in the following 30 days. Although many moderate to large earthquakes have occurred in the historical and instrumental periods of this region, these double earthquakes and their aftershocks majorly impacted lives and released great seismic energy. In this study, we interpret the gravity-magnetic data and the epicenter and hypocenter distributions of the aftershocks to correlate the tectonic structures and the active fault zones. The results of potential field anomalies reveal that the rotational anomalies in the southwestward direction are associated with the tectonic structure of Anatolia. Results show that shallow aftershocks are associated with high-gravity anomalies, whereas deeper aftershocks are associated with low-gravity anomalies and they become shallower in places where gravity values increase. After the derivative transformations are applied to the magnetic anomalies, it is seen that the faults and regions of magnetic discontinuity are in good agreement. Consequently, the findings on gravity, magnetic anomalies and aftershock sequences demonstrate that the first mainshock occurred in the unbroken segment of the East Anatolian Fault Zone.
  • Küçük Resim
    Öğe
    Investigation of earthquake sequence and stress transfer in the Eastern Anatolia Fault Zone by Coulomb stress analysis
    (TUBITAK, 2024) Büyüksaraç, Aydın; Alkan, Hamdi; Bektaş, Özcan
    A devastating earthquake with a magnitude of (Mw = 7.7) occurred on February 06, 2023, in the Pazarcık segment of the Eastern Anatolian Fault Zone, which has not shown major earthquake activity for a long time. On the same day, another earthquake with a magnitude of (Mw = 7.6) occurred in Ekinözü-Elbistan (Kahramanmaraş) in the northwest. Three more earthquakes with magnitudes of Mw = 6.6, Mw = 5.9, and ML = 5.7 occurred on the same day, and significant damage, loss of life, and property occurred in 11 provinces and districts. A sixth earthquake occurred with Mw = 6.4 magnitude in Defne-Hatay on February 20, 2023. In addition, more than 32,000 aftershocks were recorded while this study was in progress. The interconnection of these earthquakes was investigated by Coulomb stress analysis. It showed compatibility with the distribution of both these six earthquakes and small aftershocks, in which earthquakes transfer stress to each other during their formation phases. By calculating Coulomb stress changes, mainshock ruptures have played an important role in transferring stresses between Elazığ and Malatya in the northeast, Kahramanmaraş-Göksun in the west, and Hatay and Syria in the south. Also, our calculations showed that shallow depths in and around source zones received positive stress changes (~1.0 bar) due to the focal depths of mainshocks with their aftershocks. Finally, it has been better understood with these earthquakes that the stress transfer time of high-energy earthquakes can be shortened considerably.
  • [ X ]
    Öğe
    Statistical and seismotectonic analyses of the Marmara region under existing stress regime in the west of the NAFZ
    (Springer Int Publ Ag, 2024) Alkan, Hamdi; Ozturk, Serkan; Bektas, Ozcan; Buyuksarac, Aydin
    The Marmara Region is an active tectonic region in northwestern T & uuml;rkiye, 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 M & uuml;refte-& Scedil;ark & ouml;y, 1953 Yenice-G & ouml;nen and 1999 & Idot;zmit 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.