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The earthquakes that struck eastern Türkiye and Syria on 6 February 2023 force us to evaluate the models of seismic hazard and risk developed at the European scale for the region, specifically the 2020 European Seismic Hazard Model (ESHM20, Danciu et al.. 2021) and European Seismic Risk Model (ESRM20, Crowley et al.. 2021).We first verified that the ruptures associated to the two main earthquakes are present within the inventory of ruptures within the source model (the earthquake rupture forecasts or ERFs) for the East Anatolian Fault (first event) and Sürgü-Cardak Fault (second event. Ruptures close in magnitude and dimension to those observed were present in the ESHM20 ERFs.Preliminary ground motion observations were found to be consistent in their prediction of the expected shaking and its attenuation. Recorded near-fault ground motions also suggest strong pulse-like behaviour, indicating the need for such phenomena to be better captured in the GMMs.We have finally run scenario risk calculations using the ESRSM20 site, exposure and vulnerability models for the two main earthquakes. Expected fatalities were lower than those reported at the time of writing; however, many factors contribute to this. Further analysis is on-going to understand the difference, but critical areas for future improvement to the risk models should include state-dependent fragility, modelling of further epistemic uncertainty in exposure and vulnerability, and inclusion of spatial- and temporal correlations in ground motions across a region.List of ESHM20 and ESRM20 core team members (all co-authors of this abstract) on www.efehr.com, The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The 1:10 scale model of the 15th century Mustafa Pasha Mosque in Skopje, that underwent a comprehensive shake table program, is modeled by the discrete elements approach. A rigid block model with nonlinear behavior concentrated at the joints was developed and calibrated by comparison with the observed response. Time domain analyses of the discrete model were performed under the various levels of dynamic excitation used in the shake table test. Under the lower levels of input, the time and frequency domain characteristics of the shake table experimental response were fairly well simulated by the numerical model. This model also predicted well the zones and the level of damages. For the higher input levels, the comparison was less satisfactory. Overall, the discrete element approach showed the capability to handle the dynamic nonlinear modeling of relatively complex masonry structures. (C) 2016 Elsevier Ltd. All rights reserved.

Department of Earthquake Engineering of Kandilli Observatory and Earthquake Research Institute of Boğaziçi University (DEE-KOERI) has designed and been operating a significant number of structural monitoring networks in Istanbul. The majority of them are in historical and critical structures. The structural networks installed in the historical buildings include the 35-channel Hagia Sophia Museum; 47-channel Fatih Mosque; 27-channel Süleymaniye Mosque; 30-channel Sultanahmet Mosque and the 35-channel Mihrimah Sultan Mosque systems. Each system consists of 3-component accelerometers placed in structurally critical locations. In the Hagia Sophia Museum, Fatih Mosque and Mihrimah Sultan Mosque networks, in addition to accelerometric stations, four two-channel tiltmeters are installed. Among the monitored structures, the 6th century Hagia Sophia is the oldest one. The Sultanahmet mosque, which is a 17th century building, is the youngest one. We also monitor two minarets in Istanbul. The first minaret is one of the masonry minarets of the Hagia Sophia Museum. The other is the reinforced concrete minaret of the Maltepe Mosque which currently is the tallest modern minaret in the city. The monitoring systems installed in historical structures in Istanbul are unique, as they form the largest group of monumental structures in the world monitored in the same city and under similar earthquake hazard conditions. 44-channel Fatih Sultan Mehmet Bridge (the 2nd Bosporus bridge);, 36-channel Sapphire Tower; and 15-channel each Kanyon Building and Isbank Tower; and finally the Enron Power Plant are the engineering structures monitored by DEE-KOERI. Data from the structural monitoring networks are transmitted in real time to the monitoring center at the DEE-KOERI. An in-house real-time modal analysis software is used to process and analyze the data. The software includes data processing, spectral identification and animation modules. The results are displayed in real time, showing the time variations of modal properties and the structure’s configuration. In the paper we report on the characteristics of the networks mentioned, provide insight into the data received, carry out a comparative analysis of records focusing on differences of the structural systems they are installed in.

Minarets are important elements of mosques that constitute the essence of İslamic art. They are tall and slender structures. Old ones are mostly made of cut-stone-block masonry and occasionally of brick masonry, while the new ones are generally of reinforced concrete. They have suffered significant damage during past earthquakes, the most recent event being the 23 October 2011 Van, Turkey earthquake, underlining the need for their maintenance, preservation and protection. İstanbul, the largest city of Turkey, is home to many historical and modern minarets. Assessment of their dynamic behavior is significant due to the expectation of a large event in the near future. This study shows the results of the dynamic nonlinear analysis of two masonry minarets of different heights to better understand its structural behavior under seismic conditions. The numerical models were created using 3DEC by discrete element method that can be viewed as assemblies of masonry units, interacting along their contact surfaces. The numerical analyses were performed using a series of sine-wave excitations by gradually changing the frequency and amplitude of input velocity. Displacement magnitudes, maximum shear and normal stresses, maximum shear and normal displacements and relative displacements were recorded for each level of velocity input. The results are evaluated and compared with those previously obtained from the analyses carried out under real and synthetic earthquake inputs.