Assessing social vulnerability is essential to understanding how communities may experience and recover from disruptive events. Such an impact assumes specific features when the communities are located in cross-border-regions (CBRs). This study evaluates social vulnerability related to seismic hazard in the CBR shared by Albania, Greece, and North Macedonia, an area exposed to high seismic hazard due to its location along active tectonic structures of the Hellenic and Balkan regions. To do so, the Social Vulnerability Index (SoVI) framework is applied and adapted to the features of CBRs.The indicators selected for the SoVI assessment capture key dimensions of vulnerability, including demographic structure, socio-economic conditions, institutional performance, and service availability. To account for heterogeneity in the scale of data availability and differences in indicator importance, two scenarios are analysed using alternative weighting schemes for each indicator. The results reveal a strong influence of methodological choices on social vulnerability outcomes, as well as the need to address CBR social vulnerability in an integrated manner. The spatial variability of SoVI across and within national borders highlights key differences in how vulnerability manifests across distinct administrative and socio-economic contexts. In addition, integrating SoVI with seismic hazard using a simplified social risk matrix approach enables the identification of priority areas for targeted mitigation measures, emergency planning, and resilience-oriented policy interventions. Overall, the findings emphasise the importance of harmonised methodologies and integrated indicator systems in capturing the differentiated nature of social vulnerability in complex cross-border environments and its impact on the seismic social risk.

Recent evidence shows that multi-hazard events are becoming more frequent across Europe, highlighting the need to move beyond single-hazard approaches and toward integrated risk assessment. Despite recent advances, four key gaps persist: limited quantitative research on hazard interactions; model complexity that restricts large-scale applicability; narrow hazard coverage with insufficient integration of climate change scenarios; and neglect of cumulative impacts from sequential events. This study makes two complementary contributions. First, it proposes a scalable, unified multi-hazard risk assessment framework applicable at regional and European scales. In this framework, multi-hazard considerations are embedded throughout the entire assessment process-from study domain definition and loss metrics, through hazard characterization and conceptual incorporation of dynamic vulnerability, to the probabilistic treatment of hazard interactions and compound effects via a probabilistic, conditional-dependency framework conceptually represented as a Bayesian network. Second, based on the literature review conducted in this study, no prior European study was identified that combines flood, earthquake, and earthquake-triggered landslide hazards at the asset level for educational facilities. Therefore, this work is, to the best of the authors' knowledge, among the first such quantitative, asset-level multi-hazard risk assessments. The framework is demonstrated for over 1700 school buildings in the Region of Central Macedonia, Greece, using pan-European open-access datasets (ESHM20, ESRM20, JRC, GIRI, and ELSUS v2), making it readily transferable across Europe. By supporting risk-informed prioritization of mitigation and resilience investments, this work is consistent with the broader objectives of the Sendai Framework and the UN Sustainable Development Goals, particularly SDG 11 and SDG 13.

Interface nonlinearity of shallow foundations has been found to significantly impact the dynamic response of soilstructure-interaction (SSI) systems; however, challenges remain in both its experimental and numerical characterisation. This study presents real scale free and forced vibration experiments, as well as three-dimensional nonlinear finite element analyses, to investigate the impact of interface nonlinearity, with particular emphasis on foundation rocking, on the response of an SSI system. The system comprises a steel frame structure, EUROPROTEAS, configured with either an 18 Mg or a 9 Mg structural mass and founded on a surface footing over soft soil. The study focuses on key parameters that influence interface nonlinearity, including structural weight, interface gaps, and static normal stresses that arise at the interface due to the structural self-weight and by densification from previous testing. Further development of an interface model is proposed which allows a more realistic simulation of the static stress distribution prior to the application of dynamic excitation. Both experimental and numerical data demonstrate the significant influence of interface nonlinearity on period lengthening and damping reduction, while also highlight a scenario where it can lead to a stiffer response. Additionally, the study emphasises the significant impact that the initial stress distribution can have on the response, demonstrating that a more uniform distribution can facilitate foundation rocking. Finally, it is demonstrated that a lighter structure can exhibit stronger interface nonlinearity than a heavier one, particularly when the external excitation is applied directly to the structure.

We aim to assess the influence of soil-structure interaction (SSI) and site amplification (SAmp) effects on the seismic response of steel frame structures. In particular, idealized steel structures are examined. Typical soil materials and profiles are selected according to Eurocode 8 and simulated with finite elements using OpenSees. Then, incremental dynamic analyses are carried out using actual earthquake records of increasing intensity. The study of the steel frames is performed for two foundation models: (a) fixed-base and (b) Beam- on-Nonlinear-Winkler-Foundation spring-type foundation elements. The results of the dynamic analyses are indicatively presented and discussed based on both the relative displacement of the floors and the moment- rotation curve at the ends of the beams and columns. The thorough analysis and comparison of the results demonstrate the significant contribution of various subsoil configurations and SSI to the seismic behavior of steel frames. The methodology can be used to assess further the influence of SAmp and SSI on steel structures' seismic fragility and vulnerability.

The objective of this paper is to propose a harmonized methodology for earthquake-induced landslide hazard and risk assessment at a regional scale, which can be applied to regions where differences and limitations of data exist, for example, cross-border regions. In terms of hazard, the proposed framework consists of several steps, starting from landslide susceptibility mapping and creation of critical acceleration maps, towards defining landslide hazard maps of earthquake-induced landslides, represented by expected permanent ground deformation (PGD) for different earthquake scenarios. In terms of risk, a unique methodology, including approaches for both basic services—structures (i.e. hospitals and schools) and critical infrastructures (i.e., bridges)—is implemented. The proposed framework is applied at a regional scale to the cross-border region of three countries, North Macedonia, Albania, and Greece, for a defined exposure model consisting a total number of 191 school buildings (57 in N. Macedonia, 19 in Greece, and 115 in Albania), 46 health care structures (16 in N. Macedonia, 17 in Greece, and 13 in Albania), and 372 bridges (165 in N. Macedonia, 16 in Greece, and 191 in Albania). The results of the hazard and risk assessment show that the proposed framework is valuable, fast, and relatively easy to implement and gives a good overview of the hazardous area and defined risk of the analyzed structures, especially where only limited geomorphological, geological, and seismological datasets along with exposure database exist at a regional scale. Obtained data have been included in a web-based platform designed to collect, organize, and visualize the target area including the landslide risk scenarios related to the exposure dataset considered. The presented research was performed in the framework of the project named CRISIS (“Comprehensive RISk assessment of basic services and transport InfraStructure”) supported by the Union Civil Protection Mechanism and can be applied to other transboundary regions of interest with certain limitations, thus contributing towards improved long-term risk mitigation strategies.

For years, soil-structure interaction (SSI) has been a subject of interdisciplinary studies, although full-scale SSI experiments and the use of real data are rare. To study SSI in a well-known and controlled environment, a full-scale experiment, EuroMASS, was conducted at the Piana di Toppo test site in Northeast Italy. For the needs of the experiment, a simple structure consisting of a lumped mass overtopping a steel column on a concrete base was designed and assembled at the test site. In April 2022, a three-component instrumentation network was installed to record the seismic noise, weak earthquake motions, and active source signals to study the structure, the foundation, and the soil seismic responses. The experiment was designed to collect data that can be used for accurate dynamic characterization of the structure and analysis of wave propagation in the soil-structure system.

This work presents ongoing research activities conducted as part of the RESPOND (REal Scale experimental assessment of Pile grOup dyNamic impedance) project, funded under the EU ERIES Transnational Access (TA) initiative. The project focuses on investigating the dynamic behavior of full-scale pile groups embedded in the well-documented subsoil of the EuroSeistest site, located in the tectonically active Mygdonian basin, 30 km NNE from Thessaloniki, Greece. A 2x2 pile group consisting of four identical bored piles, each with a diameter of 0.60 m and a length of 10 m, was realized. These piles are connected to a 3x3x0.4 m pile cap, serving as the foundation for a 5 m high model structure. The experimental results have a remarkable value for a reliable design and analysis of structures founded on piles in seismic areas, since soil-structure interaction (SSI) may have a prominent role in the dynamic behaviour of the superstructure. The project is therefore expected to provide a better understanding of fundamental mechanisms associated with dynamic SSI problems, to validate existing formulae for pile group impedances and eventually propose modifications and indications for applications involving moderate non-linearities in the soil.

A multi-purpose and multi-scale tool for the seismic vulnerability and risk classification of critical buildings, such as schools, is proposed for pre- and post-event decision-making to mitigate the risk and reduce losses. The herein proposed “RiskSchools” system, is capable of performing the seismic risk assessment and grading of school buildings at various scales (district, municipality, region etc.), using (a) a pre-seismic rapid visual screening and grading of the school buildings in different vulnerability-risk classes and (b) a seismic risk assessment of the school buildings population, applying probabilistic or scenario-based methods for the seismic hazard and analytical methods for the vulnerability and risk assessment, also leading to a grading of the buildings’ risk. The results of the two approaches are compared and combined through a flexible and adaptable expert elicitation scheme to provide a final classification of the seismic risk of the school buildings in the scale of interest and a prioritization scheme with respect to the need for seismic upgrade and retrofitting. The RiskSchools system consists of a powerful, state-of-the-art, user-friendly, and easy-to-use smartphone application for the compilation of the inventory and the rapid visual screening, and a project-dedicated multi-purpose webGIS platform for the seismic vulnerability and risk classification of school buildings at any scale. Although it is initially developed and applied to the school building stock of the Region of Central Macedonia in Greece, it has been specifically designed to be easily applied to other regions of Greece and worldwide and adapted to other critical buildings, like health care and hospital buildings. The ultimate scope of the RiskSchools System is to allow for the optimal design of decision-making procedures in support of disaster management to enhance critical buildings resilience.

Our study introduces a methodology to improve large-scale seismic damage assessment by incorporating site-specific fragility curves, considering soil–structure interaction (SSI) and site amplification (SAmp) effects. The proposed method proposes an enhanced building exposure model, using publicly available data and the open-source OpenQuake Engine software. The objective is to determine whether a more refined approach incorporating SSI and SAmp can impact the final damage calculation. We evaluate our approach by estimating the damage distribution for the Thessaloniki 1978 earthquake scenario using the actual building stock of Thessaloniki. We present several maps with aggregated damages at different levels to investigate the spatial variability of SSI and SAmp, and their influence on the resulting damages. Our estimated physical damages have been compared with those obtained using approaches from the existing literature. Apparently, using an updated building exposure model to assess damages makes any comparison with past observed damages challenging. Nevertheless, incorporating SSI and SAmp in large-scale damage assessment can provide valuable support for strategic decision-making in cities and improve the accuracy of the expected loss assessment due to a seismic event.

CRISIS project aims at improving the disaster and emergency management through building a harmonized and efficient system for risk assessment of basic services and transport infrastructure in the targeted cross-border region. The main project activities include: (1) Cross-border multi hazard assessment; (2) Needs assessment; (3) Cross- border multi-risk assessment; and (4) Development of cross-border web base platform for risk assessment and management. The main stakeholder of the project is the civil protection and disaster management national authorities in the cross-border region where more than 500.000 inhabitants live, as well as all academic partner institutions that will share the knowledge and strengthen the mutual cooperation.

We present the outcomes derived from controlled laboratory experiments on utilizing gravel rubber mixtures (GRM) as a geotechnical seismic isolation (GSI) stratum beneath the foundational structure of the EuroProteas prototype. The study encompassed three distinct GRM compositions characterized by varying rubber proportions relative to the total mixture weight (0%, 10%, and 30%) employed as the foundation soil. These GSI-structure systems were subjected to external harmonic forces applied atop the structure of EuroProteas across a broad spectrum of frequencies and force magnitudes. Preceding the commencement of field experiments, resonant column and cyclic triaxial compression assessments were conducted on specimens featuring identical rubber fractions and mean grain size ratios. Our laboratory tests revealed that an increase in rubber content resulted in a reduction of the shear modulus (Go) and an augmentation of the damping ratio (Do) while concurrently inducing a more linear character in the G/Go-logγ-D profiles. The findings derived from the laboratory examinations align closely with those ascertained from field investigations. Expressly, it was confirmed that a GSI layer with a thickness of 0.50 meters, composed of a GRM incorporating 30% rubber content, exhibited a discernible reduction in the overall stiffness of the GSI-structure system, accompanied by a corresponding alteration in its fundamental vibrational frequency. The enhanced damping within the system manifested through observable reductions in acceleration recordings and diminished strain development at the base of the GRM layer with 30% rubber content, encompassing a wide range of frequencies.

Within an ongoing German-funded research project, a series of beam-to-column joints with dissipative bolted connections was developed for Moment-Resisting Frames designed for moderate seismicity. Due to the new provisions of the German National Annex to EN 1998-1, seismic hazard has gained increased importance, resulting in extended seismic areas and higher spectral acceleration. Additionally, in soft soil formations, the seismic response of a structure may be influenced by its interaction with the soil-foundation system, thus deviating from the traditional fixed-base design/assessment assumption. While the motivation was to find solutions to address these challenges, the approach was to develop pre-qualified dissipative beam-to-column joints classified as semi-rigid and equal/partial-strength for office and industrial buildings that could allow for the use of behavior factors in the range of 1.5–3. End-plate connections based on the German catalogue of typical connections were optimized to perform beyond the elastic range and experimentally investigated on full-scale frame specimens under monotonic and cyclic loading. Alongside an introduction and a description of the case-study structural system (i.e., a steel MRF with dissipative connections), the current paper is focused on the: description of the numerical structural model; consideration of foundation and underlying soil conditions; nonlinear response history analysis of the steel MRF assuming fixed boundary conditions; influence of the SSI on the structural response; main conclusions.

The recent devastating 2023 T & uuml;rkiye earthquakes underscored the urgent need for an early estimate of quantitative losses following destructive seismic events. This study aims to propose and validate a Rapid Damage Assessment (RDA) methodology based solely on open data and tools, easily and readily available globally immediately after a seismic event. In this context, the 2023 T & uuml;rkiye earthquakes are used as a case study. For the application of the proposed methodology there are two prerequisites: (1) ground shaking data, herein obtained from the US Geological Survey (USGS) ShakeMap system, and (2) a predictive seismic risk model appropriate for the area of interest, consisting of an exposure and a vulnerability model, derived from the 2020 European Seismic Risk Model (ESRM20). Scenario-type analyses for the two major events, the M7.8 Pazarcik and the M7.5 - Elbistan earthquake, are performed, and the results are compared with the officially reported damages. The main goal is to assess the accuracy of RDA immediately after an earthquake, and whether and to what extent the RDA results can be improved as the USGS ShakeMaps are updated with the incorporation of additional data, and with disaggregation of the exposure model at a finer resolution. The results indicate that the exposure model's disaggregation reduces the damage estimates' standard deviation. At the same time, the effect of the ShakeMap version is minimized when the complete fault rupture is incorporated into the model. The estimated damages are in good agreement with the officially announced data at large scale, which corroborates the proposed methodology, as well as the adopted components of ESRM20.

Mitigating seismic risk for critical facilities is crucial for governments, decision-makers, researchers, society, and the economy in earthquake-prone regions in Europe and worldwide. The paper discusses some essential concepts and methods for developing and implementing a real-time risk assessment methodology through a specific testbed example in light of an engineering-based seismic risk reduction approach for critical buildings. The goal is to demonstrate that real-time seismic risk assessment of a target building could be feasible by combining a calibrated earthquake early warning system (EEWS) with the knowledge of structure-specific fragility curves evaluated with the aid of well-designed structural monitoring arrays. The whole approach is illustrated for a school building located in Thessaloniki city center. The target school is instrumented with permanent and temporary monitoring arrays using commercial accelerometric/velocimeter stations and special in-house developed low-cost Micro-Electro-Mechanical Systems (MEMS). Structural health monitoring (SHM) allows identifying the dynamic characteristics of the building and, finally, generate structure-specific fragility functions, which may differ from generic ones. Past and current seismic events recorded on the regional seismic network and locally on sensors installed at the school building are used for the calibration and validation of the regional EEWS in order to reduce the rate of false or missed alarms. The refined structure-specific fragility functions are incorporated into the central database and used by the developed real-time risk assessment software for the promptly prediction of seismic damages and losses. The performance of the whole system is effectively checked for a strong seismic event by reproducing the Mw 6.5, 1978 Thessaloniki destructive earthquake based on 3D physics-based numerical simulations.

Earthen structures made of adobe bricks are complex systems that making the identification of their behavior difficult, especially when they have to sustain lateral forces such as seismic forces. This paper presents a numerical investigation for the assessment of the structural response of unreinforced adobe masonry structures and how the installation of wooden ring beams contributes to their overall resistance. In the framework of the numerical investigation, finite element models were created to simulate the response of an adobe building with and without the presence of wooden ring beams. The test building is located in Cyprus, in the South Eastern Mediterranean region which is a seismic area. The material properties used in this study were found in the literature and were based on experimental data for local materials. The models were subjected to earthquake loads, performing time history analyses for the calculation of pertinent displacements and stresses. The findings indicate that integrating wooden ring beams reduces the fundamental period by 6% and modifies the building’s seismic behavior. This modification is evident not just in the magnitude of the stresses but also in their distribution, leading to a stratified stress profile. Peak stresses are primarily concentrated around the ring beams.

Evidence of past earthquakes highlighted the seismic vulnerability to buildings due to soil liquefaction and lateral spreading phenomena. Damage to buildings on a liquefiable site, especially on a gently sloping site, can be severe. The liquefied soil can undergo permanent lateral ground displacements as large as several meters in some cases, which can be severely disastrous to buildings. Recent physical tests and effective stress analyses of nonlinear dynamic soil-structure interaction (SSI) proved that simplified empirical processes are often improper for evaluating liquefaction-induced building settlements. A better understanding of the SSI effects is also essential in cases where the underlying soil is susceptible to liquefaction. In this respect, the interaction of the earthquake excitation and ground failure (i.e. soil liquefaction and lateral spreading) for buildings considering SSI is investigated herein. Typical low-code reinforced concrete (RC) frame buildings of different heights with shallow spread footings on liquefiable level-ground or sloping soils subjected to ground shaking are considered. The direct SSI approach is implemented. Predictive relationships are established between the maximum normalized differential displacements (horizontal or settlement) and the permanent ground displacement (PGD) vector at the level of foundation for low-code RC frame buildings with shallow spread footings on soils with high liquefaction potential subjected to ground shaking. Finally, vulnerability is expressed in terms of fragility and vulnerability curves as well as in terms of fragility surfaces as a function of two intensity measures.

Over the past 50 years, there has been a tremendous growth in research in the field of seismic geotechnical engineering, producing very valuable results and highlighting the decisive role of the soil filter effect and soil-structure interaction in evaluating structural seismic risk. However, the challenge in assessing and mitigating seismic risk is not entirely over, with the continual opening up of new scenarios. A need to safeguard the ecosystem is encouraging researchers to find new solutions that combine seismic risk mitigation and ecosystem protection. Soil-rubber mixtures (SRM) have emerged as a new technique to improve the soil underneath foundations, so that seismic energy will be partially dissipated within the SRM. The rubber grains are manufactured from scrap tyres, disposal of which has become a severe environmental problem worldwide. SRMs are characterized by low specific weight, high elasticity, low shear modulus, and high damping. The present paper reports some interesting results obtained by the authors as regards seismic microzonation, local site response, and soil-structure interaction. Finally, the paper reports the main results of the first tests performed on a full-scale soil-SRM-structure system and a FEM simulation of these tests.