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The study aims to analyze the structural damage to buildings, the condition of infrastructure systems, geological and geotechnical features, the impacts on the environment, and the social effects of the earthquake. More than 110 researchers from different institutions voluntarily worked together and offered their expertise for this report.
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... In the Türkiye-Syria earthquake, it was reported that 59,259 people were killed, 121,704 were wounded, and 297 went missing [2]. It is also reported that in the Türkiye-Syria earthquake, over 120,000 structures were destroyed or severely damaged [3]. Despite the first earthquake's devastation, many structures that sustained experienced more severe damage by the second earthquake, Adıyaman is most affected by earthquakes [4]. ...
Multiple earthquakes are reported in many locations around the world, recently on February 6, 2023, in Türkiye two earthquakes of magnitude 7.7 and 7.6 struck with a time interval of approximately 9 h resulted in huge destruction and collapse of structures. The lesser time interval between seismic events leads to the collapse of the structures which were damaged by the first earthquake. Most of the seismic codes do not consider the influence of multiple earthquakes, which makes the structures vulnerable to multiple earthquake phenomena. Bidirectional Incremental Dynamic Analysis (IDA) is performed on regular (S1R) and irregular (S2I) structures that are considered to access the effects of single and multiple earthquakes. The response of the structures is accessed in terms of roof displacement, storey drift ratio, IDA curves, and fragility curves generated for the suite of eleven ground motions. Results obtained from the bidirectional IDA analysis showed the effect of multiple earthquakes is significant and also the irregular structures are of greater risk under multiple earthquakes. It is noticed that from fragility curves in comparison with regular structures irregular structures are 11.11% and 27.78% more susceptible to multiple earthquakes along X and Y-direction. For S1R and S2I when subjected to multiple earthquakes, the average increase in maximum drift ratio is 29.30% and 36.44% along the X-direction, and for multiple earthquakes along the Y-direction, it is 36.42% and 40.34%. It is preferable to avoid adding irregularity into constructed structures, incorporating multiple earthquake occurrences into modern seismic regulations is advantageous.
... Postevent reconnaissance and ground failure documentation occur rapidly after each event and include a combination of field work, observations from remotely sensed imagery, and light detection and ranging (LiDAR) imaging of buildings to determine settlement (Ansari, Zaray, et al., 2023). Liquefaction observations were documented in a series of publications, including the reconnaissance report coordinated by the Türkiye Earthquake Reconnaissance and Research Alliance (Çetin and Ilgaç, 2023), the Geotechnical Extreme Events Reconnaissance (GEER) Association Reports in May 2023 (GEER-EERI, 2023a) and June 2023 (GEER-EERI, 2023b), and finally in K. O. Cetin et al. (unpublished manuscript, 2024, see Data and Resources). The GEER reports were developed jointly with the Earthquake Engineering Reconnaissance Institute (EERI). ...
... This study explored how preliminary reconnaissance survey data can be integrated with regional and global liquefaction inventory data to improve liquefaction modeling accuracy for a specific event. For the purposes of this study, we divided the reconnaissance data into two batches based on the timing of data availability: the first batch (batch 1) includes 163 unique liquefaction points from the initial report by Çetin and Ilgaç (2023), and the second batch (batch 2) includes 284 unique liquefaction points from all the phases of the GEER-EERI joint venture reconnaissance and other points collected by various collaborators that are documented on the SiteEye web portal (see Data and Resources). Figure 1 shows the geospatial proxies (PGV, V S30 , DW, WTD, and Precipitation) used in the GGLM-2017 model, plus the resulting liquefaction probability map, downloaded from the USGS event page for the M 7.8 mainshock. The USGS implements the thresholds recommended by Rashidian and Baise (2020) to moderate (reduce) liquefaction overpredictions, as well as the spatial extent correction recommended in Zhu et al. (2017) and a magnitude scaling factor (Allstadt et al., 2022). ...
... These events and their sources are summarized in Table 2. The third training subset includes the liquefaction observation described in the preliminary reconnaissance report by Çetin and Ilgaç (2023), following the initial reconnaissance that began on 7 February 2023. ...
A global geospatial liquefaction model (GGLM‐2017) was previously developed (Zhu et al., 2017) using logistic regression (LR) and is currently used by the U.S. Geological Survey as the preferred liquefaction model to map liquefaction probability immediately after the occurrence of earthquake events. This research proposes an ensemble modeling approach to improve the performance of the GGLM‐2017 for geospatial liquefaction modeling of the 2023 Türkiye earthquakes using an updated inventory of liquefaction occurrence locations in Europe (the OpenLIQ database, which includes prior events occurring in Türkiye) and a new inventory from the 2023 Türkiye earthquakes (gathered from multiple sources). Using the same geospatial proxies for soil saturation, soil density, and earthquake loading, and the same non‐liquefaction sampling strategy used to develop GGLM‐2017, the proposed ensemble method is validated on the data of the 2023 Türkiye earthquakes by integrating four models, including global (GGLM‐2017), continental (LR model trained on eight European events), regional (LR model trained on three historical events in Türkiye), and event‐specific (LR model trained on partially available data from the 2023 Türkiye earthquakes) models. The inventory from the 2023 Türkiye earthquakes is split into two batches, in which the first batch (163 liquefaction occurrences) resulted from the preliminary reconnaissance and is used for training the event‐specific model, and the second batch (284 liquefaction occurrences) resulted from a more complete reconnaissance (which was made available later) and is used for validating all models. The rationale for using the first batch for training the event‐specific model is to exploit the information as they become available to optimize the performance of global model in liquefaction prediction. The final ensemble probability assignment is done by averaging the probabilities derived by the four individual models, and a 50% threshold is used for classification accuracy evaluations. Comparative analysis of the ensemble model’s performance with the GGLM‐2017 showed improved predictive accuracy, resulting in higher liquefaction detection for the specific event under study (the 2023 Türkiye earthquakes). The ensemble model also provides an estimate of model uncertainty.
... Soil liquefaction is defined as a significant loss of strength and stiffness due to the development of excess pore water pressures resulting in zero effective stress in the soil during a seismic event (Cetin and Ilgaç 2023). The soil liquefaction phenomena were predominantly observed in the İskenderun district of Hatay, affecting both existing structures and open areas. ...
Two successive earthquakes with moment magnitudes of Mw = 7.7 (focal depth = 8.6 km) and Mw = 7.6 (focal depth = 7 km) occurred approximately within 9 h on February 6, 2023, in Türkiye, respectively. The epicenters were the Pazarcık and Elbistan districts of Kahramanmaraş. Both earthquakes occurred in the East Anatolian Fault Zone, one of Türkiye’s two major active fault systems. Between these two severe earthquakes, there was one more big aftershock with a moment magnitude of 6.6, the epicenter of which was in the Nurdağı District of Gaziantep. Then, on February 20, 2023, another aftershock earthquake with a magnitude of Mw = 6.4 occurred in Yayladağı district of Hatay. As a result of the earthquakes, severe damage occurred in several provinces and districts with a population of around 15 million, and more than 50,000 people have lost their lives. This study presents on-site geotechnical and structural investigations by a team of researchers after the Kahramanmaraş earthquakes. It summarizes the performance of the building environments as a result of on-site assessments, taking into account observed structural damage, local site conditions, and strong ground motion data. The possible causes of the observed damage are addressed in detail. These earthquakes once again revealed the common deficiencies of existing reinforced concrete structures in Türkiye, such as poor material quality, poor workmanship, unsuitability of reinforcement detailing, and inadequate earthquake-resistant construction techniques. Precast concrete and masonry structures in the region were also severely damaged during the earthquakes due to insufficient engineering service, poor materials, deficiencies during construction, etc.
... Over 15 million people lived in Kahramanmaras, Adiyaman, Hatay, Osmaniye, Gaziantep, Kilis, Sanliurfa, Diyarbakir, Malatya, Adana, and Elazig were effected by February 6, Turkey-Syria 2023 earthquake[9]. ...
... Collapse of structures during Turkey-Syria 2023 earthquake[9] 3.2. Performance of buildings constructed before and after seismic provisionsThe structures constructed before the 2000 Turkey seismic provisions are suffered more, the primary reasons being the use of mild steel bars, insufficient steel in structural elements and presence of soft stories. ...
Buildings are an important components of both urban and rural infrastructure, and it is crucial that they perform well during a seismic event. The earthquakes occurred on February 6, 2023 in Kahramanmaras, Turkey, which also had an impact on eleven other locations surrounding it. Turkey has suffered significantly from fatalities as well as damage to structures and other facilities. The area was severely damaged by two earthquakes, Mw7.7 and Mw7.6, which occurred within a time window of roughly 9 hours on February 6, 2023 in Turkey. Seismic regulations only take into account the design of structures during a single earthquake; multiple earthquake occurrences are not taken into account. The performance of reinforced concrete buildings, masonry buildings, and precast buildings damaged during seismic sequences are discussed in this case study. From this study it is observed that, buildings that are subject to multiple earthquakes often collapse because of damage by previous earthquake, weak foundations, detailing errors at site, the use of poor materials, and inadequate craftsmanship. Multiple earthquakes should be considered during the analysis and design phase of structures, and seismic code regulations should be adjusted to allow for multiple earthquakes.
... Finally, we tested our model using the preliminary D 5−95 duration values from the two large earthquakes in Türkiye in February 2023: the M 7.8 Kahramanmara and M 7.7 Adana earthquakes. The D 5−95 duration data are from Cetin et al. (2023). The comparisons of the model and the observed D 5−95 data are shown in Figure 21. ...
A duration ground-motion model for crustal earthquakes based on the normalized Arias intensity (IA) is developed. Two sets of seismological simulations are used to constrain the form and scaling of the duration model. Simulations using a 3D crustal model show that an additive model for the source, path, and site terms captures the physical behavior of duration better than a multiplicative model for the site term. Stochastic finite-fault simulations are used to constrain the saturation of the large-magnitude scaling at short distances. The duration model is developed in two parts: a duration model for the time interval between 5% and 75% of the normalized Arias intensity (D5−75) and a duration model for the ratio of the D5−X/D5−75 duration for X values from 10 to 95. Together, these two models provide a more complete description of the evolution of the seismic energy with time than a single duration metric. A new aspect of the statistical model for duration is the inclusion of a random effect for the path term in addition to random effects for the source and site terms. The source and site random effects are modeled as scale factors on the duration, whereas the path-term random effect is a scale factor on the distance slope. The distribution of the duration residuals has a skewness that is between the skewness of a lognormal distribution and the symmetry of a normal distribution. The final duration aleatory variability is modeled by a power-normal distribution with an exponent of 0.3, which accounts for the amplitude dependence of the aleatory variability of the duration with smaller aleatory variability for large-magnitude events and larger aleatory variability for small-magnitude events as compared to the variability from a lognormal distribution.
This paper presents a comprehensive overview of the rapid damage assessment and reconnaissance efforts following the devastating earthquakes on February 6, 2023, in Türkiye. It specifically focuses on implementing the SiteEye Disaster Plugin, an additional component of SiteEye software developed by i4 Company engineers and Middle East Technical University researchers. This tool played a critical role in managing and analyzing a massive dataset comprising over 28,000 images and videos. The research highlights the plugin’s innovative features, such as offline data collection, georeferenced-based layering, and an integrated damage classification system, significantly improving earthquake impact assessments’ accuracy and efficiency. It also underscores the importance of interdisciplinary collaboration involving national and international teams and the role of open data in disaster management. The findings demonstrate how digital technologies can transform the field of disaster response, offering new approaches for rapid assessment and effective management in the aftermath of seismic events. This research contributes valuable insights into enhancing disaster preparedness and response strategies, particularly in earthquake-prone areas.
Seismically induced soil liquefaction was listed as one of the major causes of damage observed in the natural and built environment during the 2023 Türkiye-Kahramanmaraş earthquake sequence. Reconnaissance field investigations were performed to collect perishable data and document the extent of damage immediately after the events. The sites with surface manifestations of seismic soil liquefaction in the form of soil ejecta, excessive foundation and ground deformations were identified and documented. The deformations were mapped, and samples from ejecta were retrieved. The ejecta samples were predominantly classified as sands with varying degrees of fines. Laboratory test results performed on liquefied soil ejecta revealed that the fines-containing liquefied ejecta samples are mostly classified as low plasticity clays (CL). Most of CL soil type ejecta were retrieved from Gölbaşı–Adıyaman region. The liquid limits of these samples varied in between 32 and 38%, their plasticity index values were estimated in the range of 16–23%. Surprisingly, two ejecta samples with plasticity indices higher than 30% were retrieved from Hatay airport, one of which was classified as high plasticity clay (CH). The majority of the fine-grained ejecta samples fall either on “Zone B: Testing Recommended” region of the Seed et al. (Keynote presentation, 26th Annual ASCE Los Angeles Geotechnical Spring Seminar, Long Beach, CA, 2003) susceptibility chart. Moreover, 12 out of 74 samples fall outside the susceptible limits defined by Seed et. These preliminary results suggest that clayey soils can produce liquefied ejecta when subjected to cyclic loading. Detailed site investigation and laboratory testing programs are ongoing to further investigate this rather unexpected response. Until their findings become available, the liquefaction susceptibility of silty-clayey soils’ mixtures is recommended to be assessed conservatively with caution.
The seismograms recorded at a total of 71 strong ground-motion stations (SGMS) located within 100 km of the fault rupture were used to investigate the durational variability observed during the 6 February 2023 M 7.8 Pazarcık, Kahramanmaraş, Türkiye, earthquake. More specifically, significant duration (D) and equivalent number of uniform stress cycles (N) estimated using these accelerograms were compared with the ones predicted by Cetin et al. (2021) and Davatgari-Tafreshi and Bora (2023) models, respectively. To facilitate the comparisons, residuals were estimated and presented with reference to (1) SGMS’ geographical locations; (2) recorded peak ground acceleration (PGA) intensities; (3) distance to the fault rupture, or RJB; (4) site stiffness; and (5) angular orientation of the stations relative to the fault rupture. The assessment results reveal that during the Pazarcık event the duration parameters of D5−75, D5−95, and N were recorded as 23 s, 40 s, and 25 cycles, respectively, on average. Hatay and Kahramanmaraş emerge as the metropolitan cities with the highest PGA intensities, coupled with above-the-average significant durations. A negative correlation is evident between the duration and PGA intensity levels for stations located on the Anatolian side of the rupture, particularly pronounced for the significant duration parameters. The N, D5−75, and D5−95 values appear to be unaffected by RJB distances within 10 km, after which they exhibit an increasing trend. The significant durations were evaluated to be longer at softer soil sites. As the azimuth angle θ increases, D and N were observed to increase.
The long-term seismic regime of Turkey for the 17th - early 21st centuries are analyzed. It is shown that the fundamental feature of the seismic regime is periodic seismic activations (SA) of strong earthquakes. During the analyzed period, 14 seismic activations of various durations (from 4 to 24 years) and a different number of events (from 4 to 22) were traced. The last SA in Turkey began in 2011, and most likely did not end with the Kahramanmarash earthquake in 2023. SA, as a rule, involves the main seismically active regions of the country (the Aegean coast, the North and East Anatolian faults), but with a clear dominance a certain seismically active area with reduced activity of others. An analysis of historical seismicity shows that strong earthquakes along the North and East Anatolian faults in many cases occur in the same source zones, confirming the concept of seismic sources as inherited geological structures, which may serve as an important prognostic symptom. The Kahramanmaraş earthquakes on February 6, 2023 occurred in the framework of the seismic activation that began in 2011.The position of the Mahmaranmarash seismic source on the southern segment of the East Anatolian fault is in good agreement with displacement of seismic sources from north to south along this fault in the 20th century.
