Search Results (13)

In the earthquakes that occurred in the Pazarcık (Mw = 7.7) and Elbistan (Mw = 7.6) districts of Kahramanmaraş Province on 6 February 2023, many buildings collapsed in the Hayrullah neighborhood of the Onikişubat district. In this study, we investigated whether there was a soil amplification effect on the damage occurring in the Hayrullah neighborhood of the Onikişubat district of Kahramanmaraş Province. Firstly, borehole, SPT, MASW (multi-channel surface wave analysis), microtremor, electrical resistivity tomography (ERT), and vertical electrical sounding (VES) tests were carried out in the field to determine the engineering properties and behavior of soil. Laboratory tests were also conducted using samples obtained from bore holes and field tests. Then, an idealized soil profile was created using the laboratory and field test results, and site dynamic soil behavior analyses were performed on the extracted profile. According to The Turkish Building Code (TBC 2018), the earthquake level DD-2 design spectra of the project site were determined and the average design spectrum was created. Considering the seismicity of the project site and TBC (2018) criteria (according to site-specific faulting, distance, and average shear wave velocity), 11 earthquake ground motion sets were selected and harmonized with DD-2 spectra in short, medium, and long periods. Using scaled motions, the soil profile was excited with 22 different earthquake scenarios and the results were obtained for the equivalent and non-linear models. The analysis showed that the soft soil conditions in the area amplified ground shaking by up to 2.8 times, especially for longer periods (1.0–2.5 s). This level of amplification was consistent with the damage observed in mid- to high-rise buildings, highlighting the important role of local site effects in the structural losses seen during the Kahramanmaraş earthquakes. Full article

Türkiye, a country that suffers significant structural damage from earthquakes, was struck by two major quakes on 6 February 2023, centered in Pazarcık (M_w = 7.7) and Elbistan (M_w = 7.6) in Kahramanmaraş. These earthquakes caused extensive damage and destruction to urban concrete structures, significantly contributing to the loss of life. Inadequate designs in columns, which are meant to maintain structural integrity and transfer forces, were a primary cause of the structural damage. This study provides information about these catastrophic earthquakes, focusing on the detailed examination of damages in reinforced-concrete (RC) columns. Structural analyses were conducted on a selected RC building, taking into account the primary causes of column damage: low-strength concrete and insufficient transverse reinforcement. Five different concrete classes and two transverse reinforcement spacing options were considered to analyze the impact of concrete strength. To address the exceeded shear forces in the columns, a fiber-reinforced polymer (FRP) wrapping method was employed for strengthening. Initially, a reinforcement analysis was performed on a single column that exceeded shear force limits, followed by strengthening applications on all columns exceeding the limit shear force. The results demonstrated that carbon fibers have a significant impact on the shear forces in columns. The conclusion of the research is that FRP increases the ductility of concrete columns, enabling them to withstand seismic forces more effectively. This is vital in ensuring the integrity of structures in earthquake-prone areas. Using FRP materials can also significantly reduce the carbon footprint associated with concrete construction by minimizing the need for maintenance and extending the lifespan of structures. FRP presents a sustainable and effective solution for addressing failures in reinforced concrete columns. Its unique properties not only enhance strength and durability but also significantly improve the resilience of structures against corrosion, seismic events, and overload conditions. Full article

Disasters can be defined as natural, technological, and human-induced events that cause loss of life and socio-economic impacts in societies and stop normal life. Türkiye faces many disasters. The loss of life and economic losses caused by these disasters vary according to the type of disaster. Earthquakes are the natural disasters that affect Türkiye the most. Described as the disaster of the century, the Kahramanmaraş Earthquakes occurred on 6 February 2023 at 04:17 and 13:24 Turkish time. These earthquakes, with epicenters in Pazarcık (Kahramanmaraş) and Elbistan (Kahramanmaraş) with magnitudes of Mw 7.7 and Mw 7.6, affected 11 provinces including Kahramanmaraş, Hatay, and Malatya, killing 50,399 people and damaging 1,279,727 buildings. One of the most significant challenges following earthquakes is the issue of housing, which is addressed through the implementation of temporary housing units. This study aimed to evaluate the temporary shelter areas created after the Kahramanmaraş Earthquakes within the framework of regulations and standards in Türkiye and internationally. The study data were collected through direct observation and participant observation. For this purpose, the “Vali Saim Çotur Tent City”, which is located in the central Onikişubat district of Kahramanmaraş and is the second largest tent city, was examined. As a result of the examination, it was concluded that the tent city did not comply with national and international standards. Based on the findings and results of this study, it is recommended that disaster plans are revised and training programs organized for practitioners in order to prevent similar mistakes in future disasters. Full article

This paper utilises teleseismic Z-component data to investigate rupture propagation, extent, and velocity for two very destructive earthquakes in the East Anatolian Fault Zone (EAFZ): the $M_w$ = 7.8 earthquake near Kahramanmaras and the largest ($M_w$ = 7.5 s) aftershock at Elbistan (both on 6 February 2023). The extent of the rupture is modelled with beamforming and multichannel signal classification. The teleseismic data are derived from agencies in USA and Canada. The rupture of the $M_w$ = 7.8 earthquake is found to be bi-directional towards the northeast and southwest. Three rupture segments are identified for the Kahramanmaras earthquake between 34.5°–37.5° longitude and 37.0°–37.5° latitude, and another three are identified for the Elbistan earthquake between 36.5°–38.0° longitude and around 38.5° latitude. A total of 299 km is covered in 185 s with rupture velocities between 3.1 km/s and 3.4 km/s. Additionally, the mainshock’s splay and the second-largest aftershock’s rupture are also bidirectional, covering 150 km within 46 s. Five velocity segments are identified, three for the Kahramanmaras and two for the Elbistan earthquakes. Beamforming is efficient for identifying the velocity segments. The findings provide new insights on the evolution of the spatio-temporal rupture of the EAFZ and may serve as a basis for long-term earthquake hazard planning in the area. Full article

Huge losses of life and property occurred as a result of two independent catastrophic earthquakes on 6 February 2023 in the Eastern Anatolian Fault Zone, where no significant earthquake has occurred in approximately 500 years. The earthquakes, whose epicenters were in the Pazarcık and Elbistan districts of Kahramanmaraş province at 9 h intervals, had magnitudes of M_w = 7.7 and M_w = 7.6 and caused different levels of structural damage, especially in masonry-style structures in rural areas. In this study, the damage that occurred in masonry village schools, especially in rural areas, during these two earthquakes was evaluated in terms of the characteristics of the earthquake and within the scope of civil engineering, and the causes of the damage were discussed. The damage levels of the masonry schools examined were classified using the European Macroseismic Scale (EMS-98). Information about the Kahramanmaraş earthquakes was given and structural analyses were carried out for a widely used reference school building. The school building block was analytically modeled, and its seismic load-bearing capacities were predicted through pushover analysis in TREMURI software. The study also includes repair and strengthening recommendations for such structures. Full article

The 6th February 2023 Pazarcık and Elbistan earthquakes (M_w = 7.7 and M_w = 7.6) caused great destruction in many cities and were the disaster of the century for Türkiye. The greatest destruction was caused in the provinces of Hatay, Kahramanmaraş, and Adıyaman during these earthquakes, which were independent of each other and occurred on the same day. Information about earthquakes and strong ground motion records is given within the scope of this study. Reinforced concrete (RC) structures which constitute a large part of the urban building stock in the earthquake region were exposed to structural damage at different levels. The structural damage in the RC structures in the city center, Gölbaşı, and Kahta districts of the province of Adıyaman was evaluated within the scope of earthquake and civil engineering after field investigations. Insufficient RC, low-strength concrete reinforcement problems, RC frame failure, heavy overhang, short columns, soft story, and pounding effect are the main causes of the earthquake damage. The presence of these factors that reduce the earthquake resistance of RC structures increased the damage level. In addition, the fact that the earthquakes occurred nine hours apart and the continuation of aftershocks during that period negatively affected the damage levels. It has been observed that structures that receive the necessary engineering services during the construction and project phases ensure the safety of life and property, even if the structure is slightly damaged. In this study, we also tried to reveal whether the target displacements were satisfactorily represented by numerical analysis for a sample RC structure. Full article

On 6 February 2023, two independent earthquake pairs on the East Anatolian Fault Zone, with epicenters in Pazarcık (Mw = 7.7) and Elbistan (Mw = 7.6) districts of Kahramanmaraş province, caused great destruction. Adıyaman and Gölbaşı districts of this city are among the settlements most affected by the earthquake. Especially in the district where geotechnical damages are most observed, the destructive effects of earthquakes have been clearly observed in buildings with different structural systems. In this study, information is given about the earthquakes that hit the region and the fault zone where the earthquakes occur. Geotechnical and structural damages occurring in the villages and center of the district were evaluated within the scope of earthquakes and structural engineering. It can be stated that damages observed in the district center are generally caused by soil–structure interaction problems. The fact that masonry structures, which are widely used in rural areas, do not benefit from any engineering services has an impact on the level of damage. The main reason for the damages occurring in the reinforced concrete structures in the district is the reinforced concrete system that is not designed properly or not built in accordance with the design. This case study demonstrated the importance of earthquake–soil–structure interactions in line with earthquake-resistant building design principles. Full article

This study focuses on the identification of collapsed buildings in satellite images after earthquakes through deep learning-based image segmentation models. The performance of four different architectures, namely U-Net, LinkNet, FPN, and PSPNet, was evaluated using various performance metrics, such as accuracy, precision, recall, F1 score, specificity, AUC, and IoU. The study used satellite images taken from the area located in the south and southeast of Türkiye covering the eleven provinces which are most affected by the Mw 7.7 Pazarcık (Kahramanmaraş) and Mw 7.6 Elbistan (Kahramanmaraş) earthquakes. The results indicated that FPN and U-Net were the best-performing models depending on the performance metric of interest. FPN achieved the highest accuracy and specificity scores, as well as the best precision score, while U-Net achieved the best recall and F1 score values, as well as the best AUC and IoU scores. The training and validation accuracy and loss curves were analyzed, and the results indicated that all four models achieved an accuracy value of over 96%. The FPN model outperformed the others in terms of accurately segmenting images while maintaining a low loss value. This study provides insights into the potential of deep learning-based image segmentation models in disaster management and can be useful for future research in this field. Full article

On 6 February 2023, the M_W 7.8 Pazarcik and the M_W 7.5 Elbistan earthquakes occurred in southeastern Turkey, close to the Syrian border, causing many deaths and a great deal of property destruction. The Pazarcik earthquake mainly damaged the East Anatolian Fault Zone (EAFZ). The Elbistan earthquake mainly damaged the Cardak fault (CF) and the Doğanşehir fault (DF). In this study, Sentinel-1A ascending (ASC) and descending (DES) orbit image data and pixel offset tracking (POT) were used to derive surface deformation fields in the range and azimuth directions induced by the Pazarcik and Elbistan earthquakes (hereinafter referred to as the Turkey double earthquakes). Utilizing GPS coordinate sequence data, we computed the three-dimensional surface deformation resulting from the Turkey double earthquakes. The surface deformation InSAR and GPS results were combined to invert the coseismic slip distribution of the EAFZ, CF, and DF using a layered earth model. The results show that the coseismic ruptures of the Turkey double earthquakes were dominated by left-lateral strike-slips. The maximum slip was 7.76 m on the EAFZ and about 8.2 m on the CF. Both the earthquakes ruptured the surface. The Coulomb failure stress (CFS) was computed based on the fault slip distribution and the geometric parameters of all the active faults within 300 km of the M_W 7.8 Pazarcik earthquake’s epicenter. The CFS change resulting from the Pazarcik earthquake suggests that the subsequent Elbistan earthquake was triggered by the Pazarcik earthquake. The Antakya fault experienced an increase in CFS of 8.4 bars during this double-earthquake event. Therefore, the M_W 6.3 Uzunbağ earthquake on 20 February 2023 was jointly influenced by the Turkey double earthquakes. Through stress analysis of all the active faults within 300 km of the M_W 7.8 Pazarcik earthquake’s epicenter, the Ecemis segment, Camliyayla fault, Aadag fault, Ayvali fault, and Pula segment were all found to be under stress loading. Particularly, the Ayvali fault and Pula segment exhibited conspicuous stress loading, signaling a higher risk of future seismic activity. Full article

On 6 February 2023, two major earthquakes occurred in the Turkish province of Kahramanmaraş. The first earthquake with a magnitude of Mw 7.7 occurred in the center of Kahramanmaras, while the second earthquake with a magnitude of Mw 7.5 occurred in the region of Elbistan. These earthquakes caused heavy damage and loss of life in the affected regions. In particular, the Elbistan region experienced both earthquakes with great severity. Following the earthquakes, damage analyses were carried out on the earthquake-affected structures in this region. In the region, 1045 buildings were destroyed, 2640 buildings were heavily damaged, and 463 buildings were moderately damaged by the earthquakes. In this study, the relation between the material quality and the damage status of the affected buildings in the Elbistan region was investigated. A total of 20 buildings with heavy and moderate damage, built both before and after the year 2000, were selected for analysis. Samples were taken from these buildings, and the compressive strength values of the samples were obtained. Further, in situ experiments featuring the Schmidt and UPV tests were performed in the buildings. The results found that the buildings lacked adequate concrete strength. In particular, the post-2000 structures recorded concrete strength values below the established standard. This study proves the necessity of following established regulations in the design and construction of buildings in earthquake-prone zones, especially with respect to the construction materials used. Full article

Türkiye experienced great destruction during the Kahramanmaraş earthquake couple which occurred as Pazarcık (M_w = 7.7) and Elbistan (M_w = 7.6) on 6 February 2023. The weak structural characteristics and the magnitude of the earthquakes caused more than 50,000 casualties. Significant damage occurred in both urban and rural building stock in 11 different provinces that were primarily affected by the earthquakes. The dominant building stock is masonry structures in the rural areas of the earthquake region. Structural damages at various levels have occurred in adobe masonry structures built using local labours and resources without any engineering service. The main purpose of this study is to examine the failure and collapse mechanisms of adobe structures after Kahramanmaraş earthquakes in detail. First of all, information about both earthquakes was given. The earthquake intensity for all provinces was obtained by using the peak ground acceleration-intensity relation suggested for Türkiye, taking into account the measured PGAs in earthquakes. The observed structural damages were evaluated in terms of earthquake and civil engineering in adobe structures. Damage classification was conducted using European Macro-Seismic Scale (EMS-98) for a total of 100 adobe buildings. Of these structures, 25% were destroyed, 49% were heavily damaged, 15% were damaged moderately, and 11% were damaged slightly. In addition, the rules regarding adobe structures were compared considering the last two earthquake design codes used in Türkiye. In the study, suggestions were also presented to prevent structural damage in the adobe buildings in the earthquake region. Low strength of adobe material, usage of heavy earthen roofs, failure to comply with earthquake-resistant building design principles, and insufficient support of load-bearing walls are the main causes of damage. Full article

Two major earthquakes struck Pazarcık and Elbistan, towns in Kahramanmaraş, Türkiye, on 6 February 2023, approximately 9 h apart. The first earthquake, recorded at 04:17 local time, had a M_w = 7.7, with a focal depth of 8.6 km. At 13:24 local time, a second earthquake occurred with M_w = 7.6 at a focal depth of 7 km, approximately 90 km north of the first one. A total of 11 provinces were severely affected by these earthquakes. As of 15 April 2023, they caused close to 51,000 deaths and almost 215,000 completely destroyed/severely damaged buildings. At some locations, the largest horizontal peak ground acceleration (PGA) values of the first and second earthquakes exceeded the code-generated PGAs by almost 3 and 1.75 times, respectively. A technical team visited these areas within 15 h of the first earthquake. The purpose of this article is to present their observations, findings, and the characteristics of the two earthquakes, with comprehensive site survey results supported by photographs. This study concludes that most of the collapsed and severely/moderately damaged buildings in the region were built between 1975 and 2000, when site inspections were rare or non-existent. In addition to the high PGAs recorded in these earthquakes, it was verified that the design and construction of these buildings did not fully comply with the earthquake codes valid at the time. The collapsed buildings and their damage patterns confirm inadequate development length, violation of bending stirrup ends at 135°, deficiencies in construction materials and reinforcement configuration, noncompliance with confinement zones, violation of the strong beam-stronger column analogy, and issues related to building inspection. Based on the extent of the damage, it is strongly recommended that the structural performance inspection of all other buildings located near major fault lines, specifically those constructed between 1975 and 2000, should be completed. Since these earthquakes generated much higher PGAs, which is believed to be one of the main reasons for the extensive damage, a re-evaluation of all other PGAs along major fault lines is also recommended. Full article

On 6 February 2023 (UTC), an earthquake doublet, consisting of the Mw 7.8 Pazarcik earthquake and the Mw 7.5 Elbistan earthquake, struck south-central Turkey and northwestern Syria, which was the largest earthquake that occurred in Turkey since the 1939 Erzincan earthquake. The faulting model of this earthquake was estimated based on the coseismic InSAR and GPS displacements. In addition, the best-fitting coseismic faulting model indicates that both the Pazarcik earthquake and the Elbistan earthquake were controlled by predominated left-lateral strike-slip motion, with slip peaks of 9.7 m and 10.8 m, respectively. The Coulomb failure stress (CFS) change suggests that the Pazarcik earthquake has a positive effect in triggering the rupture of the seismogenic fault of the Elbistan earthquake. Furthermore, these two main shocks promoted the occurrence of the Mw 6.3 strong aftershock. Additionally, it is found that the 2023 Turkey-Syria earthquake doublet increased the rupture risk of the Puturge segment of the EAF fault and the northern segment of the Dead Sea Fault (DSF). It is crucial to note that the northern segment of the DSF has not experienced a large earthquake in several centuries, highlighting the need for heightened attention to the potential seismic hazard of this segment. Finally, a deformation zone adjacent to the DSF was identified, potentially attributed to the motion of a blind submarine fault. Full article