Seismic Hazard Scenarios Research Articles

Utilization of stochastic ground motion simulations for scenario-based performance assessment of geo-structures

Probabilistic seismic performance assessments of engineered structures can be highly sensitive to the seismic input excitation and its variability. In the present study, the scenario-based performance assessment recommended by Federal Emergency Management Agency (FEMA) P-58 guidelines is adopted to estimate seismic fragility of concrete dams for various seismic hazard scenarios. Due to the scarcity of recorded ground motions and thereby their poor representation of uncertainties, stochastic ground motion simulation methods are utilized to obtain the required input excitations. Moreover, to understand the uncertainty in ground motion simulation models, two broadband stochastic simulation models are used to generate input excitations representing six seismic hazard scenarios defined by earthquake magnitude, source-to-site distance, and soil conditions.Optimal intensity measure parameters for each scenario are identified using a systematic procedure that considers criteria such as efficiency, practicality, proficiency, sufficiency, and hazard compatibility. Fragility curves and surfaces are derived using the cloud analysis technique, taking into account various damage measures and limit state functions. The study finds that the derived fragility curves are particularly sensitive to the selection of earthquake scenarios, the choice of records, and the methods used to calculate fragility curves, with less sensitivity observed to different engineering demand parameters. Given this sensitivity, particularly to ground motion selection, the study highlights the necessity of incorporating both model-to-model variability (epistemic uncertainty) and record-to-record variability (aleatory uncertainty), alongside the established material and modeling uncertainties, in the probabilistic seismic assessment.

Long-term sustainability and resilience enhancement of building portfolios

The role of community building portfolios in socioeconomic development and the growth of the built environment cannot be overstated. Damage to these structures can have far-reaching consequences on socioeconomic and environmental aspects, requiring a long-term perspective for recovery. As communities aim to enhance their resilience and sustainability, there is a cost burden that needs to be considered. To address this issue, this paper proposes a community-level performance enhancement approach that focuses on optimizing the long-term resilience and sustainability of community building portfolios, taking into account recurrent seismic hazards. A Gaussian process surrogate-based multi-objective optimization framework is utilized to optimize the cost objective while considering performance indicators for resilience and sustainability. The proposed framework involves using performance-based assessment methods to evaluate the socioeconomic and environmental consequences under stochastic and recurrent seismic hazard scenarios. These evaluated indicators are then used to efficiently optimize the community resilience and sustainability, taking into account the retrofit costs. Finally, approximate Pareto-optimal solutions are extracted and utilized for decision-making. In summary, this paper presents a novel approach for optimizing the long-term resilience and sustainability of community building portfolios by considering recurrent seismic hazards. The proposed framework incorporates performance-based assessment methods and multi-objective optimization techniques to achieve an optimal balance between cost, resilience, and sustainability, with the ultimate goal of enhancing community well-being and decision-making in the face of seismic hazards.

Seismic risk reduction through retrofitting of school masonry buildings from Romania

Retrofitting the existing building stock is needed since it can cause significant losses as in case of a damaging earthquake, particularly in structures used for public services, such as schools. Effective and optimal seismic retrofitting measures applied to existing masonry constructions should arise from a strong understanding of the vulnerabilities associated with each structural typology and construction practice. Using representative structural configurations of the masonry buildings used in the education sector from Romania, the paper aims to evaluate the seismic risk associated to the existing buildings and to support informed decision-making for seismic retrofitting measures. Starting from a broad database of school masonry buildings, potential losses were evaluated considering two seismic hazard scenarios. For an earthquake having a 63% exceedance probability in 50 years, losses estimated for the education sector comprising masonry structures reached almost 240 mil. € and 2,500 potential casualties. For highlighting that investments in retrofitting masonry structures from the education sector lead to significant reductions of potential losses, prioritization criteria were proposed and cost–benefit analysis was carried out for about 15,000 buildings. Results are presented through graphs and maps that illustrate the distribution of annual failure probabilities at the national level. Therefore, the methodology proposed and the results presented in this paper can represent a valuable tool for substantiating public policies aiming at reducing the seismic risk, in particular for existing masonry structures.

Unified hazard models for risk assessment of transportation networks in a multi-hazard environment

Transportation networks play a vital role in the economic prosperity of modern societies. Recent hazardous events in Greece, for instance, the 2021 Crete earthquake, the 2021 Thessaly earthquakes and floods, and the heavy 2019 rainfall in Crete, have revealed the vulnerability of roadway networks to natural hazards, resulting in severe physical damage and important economic and societal losses. Severe damage on bridges and tunnels of roadway networks is commonly related to the effects of multiple hazards that may act independently during their life span. However, the literature on risk assessment of the above elements commonly focuses on the effects of a single hazard, disregarding the effects of various hazards in a multi-hazard environment. In this context, there is an increasing need for a reasonable and practical evaluation of the multi-hazard risk of transportation infrastructure. Research project INFRARES (https://www.infrares.gr/) aspires to gain further insight into the risk and resilience assessment of bridges and tunnels subjected to independent and/or multiple subsequent natural hazards, proposing a comprehensive framework toward a more efficient risk assessment of the above critical transportation infrastructure components. This paper presents the first part of the framework. More specifically, a unified methodology for the development and graphic presentation of single seismic- and flood-hazard scenarios, as well as of novel multi-seismic-flood hazard scenarios, are presented, providing a valuable tool for risk assessment of roadway networks for separate, combined (triggered), or subsequent hazards. The unified approach followed to develop single seismic and flood hazard scenarios is initially presented. The data required to develop such scenarios are derived from recently published and freely available data accessible via European databases; hence, allowing for a straightforward application of the proposed methodology throughout Europe. The unified approach in developing single hazard scenarios is further exploited to develop integrated seismic-flood hazard scenarios. Single and multi-hazard scenarios are graphically displayed in the form of GIS format maps, with the methodology being applied to the Greek terrain for various hazard scenarios. Recent hazard events that caused significant damage to the Greek road network are also presented to emphasize the importance of proper evaluation of natural hazards and their effects on roadway networks in multi-hazard environments. The methodology developed within this study contributes toward the generation of uniform multi-hazard scenarios for the risk assessment of various structures and networks in a multi-hazard environment.

Active fault segments along the North Anatolian Fault system in the Sea of Marmara: implication for seismic hazard

A new analysis of high-resolution multibeam and seismic reflection data, collected during several oceanographic expeditions starting from 1999, allowed us to compile an updated morphotectonic map of the North Anatolian Fault below the Sea of Marmara. We reconstructed kinematics and geometries of individual fault segments, active at the time scale of 10 ka, an interval which includes several earthquake cycles, taking as stratigraphic marker the base of the latest marine transgression. Given the high deformation rates relative to sediment supply, most active tectonic structures have a morphological expression at the seafloor, even in presence of composite fault geometries and/or overprinting due to mass-wasting or turbidite deposits. In the frame of the right-lateral strike-slip domain characterizing the North Anatolian fault system, three types of deformation are observed: almost pure strike-slip faults, oriented mainly E–W; NE/SW-aligned axes of transpressive structures; NW/SE-oriented trans-tensional depressions. Fault segmentation occurs at different scales, but main segments develop along three major right-lateral oversteps, which delimit main fault branches, from east to west: (i) the transtensive Cinarcik segment; (ii) the Central (East and West) segments; and (iii) the westernmost Tekirdag segment. A quantitative morphometric analysis of the shallow deformation patterns observed by seafloor morphology maps and high-resolution seismic reflection profiles along the entire basin allowed to determine nature and cumulative lengths of individual fault segments. These data were used as inputs for empirical relationships, to estimate maximum expected Moment Magnitudes, obtaining values in the range of 6.8–7.4 for the Central, and 6.9–7.1 for the Cinarcik and Tekirdag segments, respectively. We discuss these findings considering analyses of historical catalogues and available paleoseismological studies for the Sea of Marmara region to formulate reliable seismic hazard scenarios.

Cost-based resilience assessment of bridges subjected to earthquakes

PurposeTransport infrastructure resilience is of paramount importance for societies, therefore its quantification is urgently needed. A resilience assessment framework based on well-informed resilience indices is presented and applied for assessing the resilience of representative bridges exposed to earthquakes.Design/methodology/approachThe framework quantifies the robustness of bridges against different seismic hazard scenarios, by using realistic fragility functions and the rapidity of the recovery and/or retrofitting after the occurrence of a certain degree of damage, based on realistic restoration functions.FindingsTwo different approaches for the modeling of the restoration tasks are examined. Both direct losses due to structural damage and indirect losses due to traffic disruption are estimated.Originality/valueA new cost-based resilience index is introduced and alternate approaches for expressing the restoration strategies are examined and assessed. The results facilitate owners to enhance cost-based resilience management toward more resilient infrastructure.

Seismic resilience evaluation of base-isolated RC buildings using a loss-recovery approach

Seismic isolation systems, especially friction pendulum bearings (FPBs), are used as ideal seismic protection strategies in performance-based design. Furthermore, FPBs can increase the functionality of buildings by minimizing interruption of use of the facility (e.g., operational performance level) and reducing seismic demands on the structural and non-structural elements. The primary objective of this paper is to investigate the seismic resilience of reinforced concrete (RC) buildings, especially essential buildings in compliance with a loss-recovery approach. To this end, an analytical examination is conducted concerning a six-story RC building, which was mainly designed under the Uniform Building Code (UBC in International Conference of Building Officials, Whittier, CA, 1997) for a high-risk seismic zone. The incremental dynamic analyses of the fixed-base and base-isolated structures subjected to a set of near and far-fault ground motions are carried out for getting seismic fragility and functionality curves as well as the resilience of structures using a loss-recovery approach. The proposed methodology is employed to special buildings such as hospital buildings, with and without using the FPBs considering different seismic hazard scenarios that could occur within the investigated region. At the end of the paper, a parametric study is conducted by changing the building and pendulum parameters. The benefit of the suggested approach is found in terms of loss-recovery and seismic resilience that will be well recognized by the decision-maker for better planning to decrease seismic losses, rather than waiting for an earthquake and paying for it afterward.

Seismic loss and resilience assessment of single-column rocking bridges

This study focuses on structural systems, which are particularly attractive for bridge design. Specifically, it investigates the seismic performance of single-column bridges, which are either conventionally designed, with the column monolithically connected with the ground (i.e. fixed-base), or designed with the column-footing system able to uplift and exhibit planar rocking motion during an earthquake. Although various researchers have studied the examined structures in terms of their seismic fragility, their seismic losses, post-earthquake functionality and resilience have received less attention. This paper redirects our attention to the main benefits of rocking design over the conventional (fixed-base) design in the aftermath of severe seismic hazard scenarios. The analysis reveals the considerably mitigated (short-term and long-term) seismic losses of the rocking structure compared to the pertinent losses of the fixed-base structure. In addition, the results show the remarkable functionality and resilience of the rocking structure after all the examined seismic hazard scenarios. Importantly, this work unveils that the post-earthquake financial benefits of the rocking structure can be further increased when the structure is carefully designed. In particular, even a small modification of its slenderness can lead to a substantial enhancement of its post-earthquake performance. The above findings illustrate the potential of the rocking structural system as an alternative seismic design paradigm for bridges and serve as the basis for a more rational and holistic seismic assessment framework of single-column rocking bridges.

Detection and extraction of velocity pulses of near-fault ground motions using asymmetric Gaussian chirplet model

In this paper, a method which is based on the asymmetric Gaussian chirplet model (AGCM), adapted dictionary-free orthogonal matching pursuit (ADOMP) algorithm, and Newton method, is proposed for detection and extraction of velocity pulses. In the proposed method, the ADOMP algorithm and the Newton method find the most correlating AGCM atom at each iteration and optimize its amplitude over all of the already chosen atoms. The first chirplet atom detects the location of velocity pulse and its combination with adjacent atoms extracts the velocity pulse of near-fault ground motions. The proposed method simulates asymmetric waves, sharp and impulsive peaks of velocity pulses, successive positive or negative half cycles of velocity pulses, and multiple dominant frequency peaks of velocity pulses. Also because of optimized energy concentration of AGCM atoms, they extract high energy locations of velocity time histories accurately. The previous methods underestimate sharp peaks of velocity pulses, overestimate their smooth peaks, and consider a dominant frequency for each velocity pulse. According to the results, considering the dominant frequency of first chirplet atom as the pulse's frequency is not realistic. In the proposed model, the first chirplet atom extracts more than 70% of the energy of velocity pulses. So, it is sufficient to estimate the parameters of first chirplet atom as a function of seismological parameters to can generate synthetic velocity pulses for future seismic hazard scenarios.

Nonlinear Dynamic Analysis for Safety Assessment of Heritage Buildings: Church of Santa Maria de Belém

Despite the remarkable longevity of heritage constructions, they typically present several structural fragilities inherent to their own material and constructive features. This fact is particularly relevant when seismic loads are concerned, because a very significant portion of such constructions lack adequate seismic resistance and require retrofitting interventions in order to mitigate their vulnerability. However, to guarantee the success of the interventions, the interventions should be carefully selected based on a full understanding of the dynamic response of the building and, particularly, its most vulnerable structural elements. Due to many reasons, the issues associated with this kind of analysis are still difficult to address; therefore, research on this subject should be encouraged. Taking this into account, the church of Santa Maria de Belém, one of the most emblematic buildings of the monastery of Jerónimos complex in Lisbon, is used in this work as a case study to discuss the nonlinear dynamic response of cultural heritage buildings. The nonlinear dynamic behavior of the church was numerically simulated with a three-dimensional (3D) model using artificially generated seismic acceleration time histories, in agreement with seismic hazard scenarios for return periods of 475, 975, and 5,000 years. The dynamic response of the church is discussed and a comparison against results derived from a pushover analysis is also presented. Finally, a modal analysis is presented, estimating the damage level that would be present in the church after the occurrence of such seismic scenarios.

Site effects in Mexico City basin: Past and present

Due to the unique subsoil conditions prevailing in the Mexico City basin, seismic risk has been strongly correlated to site effects. Thus, during the Mw 8.1 09/19/1985 subduction fault earthquake, and its strong aftershock Mw 7.5 09/21/1985, extensive damage was observed in the area, along with the loss of thousands of lives, despite these events had an epicentral distance of around 430 km from Mexico City. The observed damage was mostly due to site affects originated by the high plastiCity clay deposits found in the basin, which lead to large amplifications, and duration elongation of the ground motions coming from the epicenter. In addition, a frequency content modification occurs, which in turn, leads to a double resonance effect between the incoming ground motions, soil deposits, and the damaged buildings. Exactly 32 years after this devastating event, the Mw 7.1 09/19/2017 normal fault earthquake, reminded us of the importance of accounting for site effects, and most importantly the need to carry out a proper characterization of basin geometry, soil profile configuration, hydraulic conditions, and maintenance-structure periodic assessments of the building stock in Mexico City. This is required to reduce uncertainties of seismic vulnerability studies for extreme-event seismic hazard scenarios. In this paper, the role of site response and seismic soil-structure interaction as key factors responsible of the observed damage in the City is revisited, through series of 3D finite difference models of typical structure-foundation-soil typologies found at the areas where most of the damage was observed, highlighting its clear impact in the final damage distribution observed around the City.

Agent-Based Recovery Model for Seismic Resilience Evaluation of Electrified Communities.

In this article, an agent-based framework to quantify the seismic resilience of an electric power supply system (EPSS) and the community it serves is presented. Within the framework, the loss and restoration of the EPSS power generation and delivery capacity and of the power demand from the served community are used to assess the electric power deficit during the damage absorption and recovery processes. Damage to the components of the EPSS and of the community-built environment is evaluated using the seismic fragility functions. The restoration of the community electric power demand is evaluated using the seismic recovery functions. However, the postearthquake EPSS recovery process is modeled using an agent-based model with two agents, the EPSS Operator and the Community Administrator. The resilience of the EPSS-community system is quantified using direct, EPSS-related, societal, and community-related indicators. Parametric studies are carried out to quantify the influence of different seismic hazard scenarios, agent characteristics, and power dispatch strategies on the EPSS-community seismic resilience. The use of the agent-based modeling framework enabled a rational formulation of the postearthquake recovery phase and highlighted the interaction between the EPSS and the community in the recovery process not quantified in resilience models developed to date. Furthermore, it shows that the resilience of different community sectors can be enhanced by different power dispatch strategies. The proposed agent-based EPSS-community system resilience quantification framework can be used to develop better community and infrastructure system risk governance policies.

PROPOSITION OF A SPECTRAL AMPLIFICATION MODEL FOR NEAR FAULT DIRECTIVITY EFFECT WITH UTILIZING PROBABILISTIC EARTHQUAKE SCENARIOS

Near fault ground motions with directivity effect show larger spectral demands due to their specific waveform features. Directivity effect occur due to S-wave polarization when the fault rupture propagation and waveform travel direction coincide on each other. In this situation, a pulse arises in the beginning of ground motion displacement and velocity waveforms which is mostly seen in the fault normal direction. The pulse period (Tp) is directly proportional to the earthquake magnitude (moment magnitude, Mw) and its amplitude is inversely proportional to the rupture distance (Rrup) from the site. The other characteristic of the near fault ground motions due to S-wave polarization is known as “Fling Step” in which a residual displacement is seen in the fault parallel displacement waveform. This study summarizes the observations from the effect of near fault ground motions on design spectrum. The results of these observations are used to develop simplified equations for incorporation of near fault effect in design spectrum. Probabilistic seismic hazard scenarios are utilized in this study in order to investigate the effect of fault seismicity, fault length (characteristic magnitude of the fault), pulse period and source-to-site geometry on the level of spectral amplification due to directivity effect. The near fault effect is modelled with assembling two narrow-band directivity models (Shahi and Baker 2011; Chiou and Spudich 2013) on the probabilistic seismic hazard scenarios respectively. In the last part of this study the significance of seismological and geometrical parameters on the level of spectral amplification due to directivity will be shown and discussed. The results are used to propose relationships for the incorporation of near fault directivity effect for different geometrical distributions of the sites around the fault.

Development of hazard- and amplification-consistent elastic design spectra

In the framework of the definition of a new building code for dams, the Swiss Federal Office for Energy (SFOE) has commissioned a study on the effect of site response variability on elastic design spectra for different soil conditions and seismic hazard scenarios. The goal of the study presented herein is the definition of a new set of site-dependent design spectra for horizontal and vertical ground-motion, whose design shape (scaled to peak ground acceleration) is to be compared with the present Swiss normative (SIA261, revision 2014) [43].To accomplish the task, we have created a large dataset of Fourier-domain seismic amplification functions by collecting empirical observations and site-specific ground motion models from both measured and stochastically generated velocity profiles. Fourier spectra were then converted to response spectral amplification using a combination of spectral modeling techniques and random vibration theory. Average amplification models are thus derived for different soil classes (SIA class A–E), according to the Swiss building code provisions, and for a set of magnitude-distance combinations chosen as representative of the Swiss hazard disaggregation scenario at the Sion site in Switzerland.Finally, the response spectral amplification functions from the database have been combined with the normalized uniform hazard spectra computed at Sion for return periods of 500, 1000, 5000 and 10,000 years. Based on those results, a new set of design spectral shapes is proposed for the different SIA soil classes, accounting for investigated scenario variability and including a reasoned level of conservatism dependent on the distribution of the site-specific amplification models.The proposed methodology targets the reduction in uncertainty associated with seismic design and, although originally focused and applied to the Swiss norm, it could be potentially applied to any national seismic code as a tool for developing, updating or benchmarking the current provisions in a holistic framework.

Probabilistic seismic hazard assessment in the northeastern part of Algeria

This work involves updating the evaluation of seismic hazard in Northeast Algeria by a probabilistic approach. This reassessment attempts to resolve inconsistencies between seismic zoning in regional building codes and is further motivated by the need to refine the input data that are used to evaluate seismic hazard scenarios. We adopted a seismotectonic model that accounts for differences in interpretations of regional seismicity. We then performed a probabilistic assessment of regional seismic hazard in Northeast Algeria. Based on a homogeneous earthquake catalog and geological and seismotectonic data gathered in the first part of the study, a seismotectonic zoning map was created and seven risk areas were identified. For each area, peak ground acceleration hazard maps were produced. Details of the calculations are provided, including hazard curves at periods of 0.1, 0.2, 0.33, 0.5, 1.0, and 2.0 s and uniform hazard spectra at urban locations in the area, including Setif, Constantine, Kherrata, Bejaia, and Jijel.

Insights into the possible seismic damage of residential buildings in Bucharest, Romania, at neighborhood resolution

Seismic loss estimation analysis for large cities is a very demanding yet necessary task; the modelling of such complex systems requires first of all insightful input data at good resolution, referring to local effects, buildings and socio-economic aspects. Also, the implementation of less empirical estimation methods is needed. Until recently, these requirements could not be fulfilled for Bucharest, the capital city in the European Union which is most at risk due to earthquakes. Based on 2011 and 2002 census data, standardized according to the framework of the Near-real time System for Estimating the Seismic Damage in Romania (SeisDaRo) through a unique approach, and on relevant hazard scenarios, we estimate for the first time the building damage at census tract scale. The methodology applied relies on 48 vulnerability curves for buildings, on the Improved Displacement Coefficient Analytical Method included in the SELENA software for computing damage probabilities and on deterministic seismic hazard scenarios, including the maximum possible earthquake. By using overlay analysis with satellite imagery and a new methodology integrated in GIS we show how results can be enhanced, reflecting more localized characteristics. Best practices for seismic risk mapping are also expressed. The results are promising and contribute to mitigation efforts in Bucharest.

Performance-Based Seismic Design of Shape Memory Alloy–Reinforced Concrete Bridge Piers. I: Development of Performance-Based Damage States

AbstractPerformance-based seismic design aims to dictate the structural performance in a predetermined fashion given the possible seismic hazard scenarios the structure is likely to experience. Identifying and assessing the probable performance is an integral part of performance-based design. Before implementation, accurate and practical definitions of different performance levels and corresponding limit states must be determined. This study aims to develop performance-based damage states for shape memory alloy (SMA)–reinforced concrete (RC) bridge piers considering different types of SMAs and seismic hazard scenarios. Using incremental dynamic analysis (IDA), this study develops quantitative damage states corresponding to different performance levels (cracking, yielding, and strength degradation) and specific probabilistic distributions for RC bridge piers reinforced with different types of SMAs. Based on an extensive numerical study, this study also proposes residual drift–based damage states for SMA-RC...

Fragility curves for typical steel frames with semi-rigid saddle connections

Steel structures with “saddle” type beam–column connections represent a popular construction practice in Iran. In the present paper, the seismic performance and the vulnerability of such structures are investigated. The seismic responses of three-story and five-story structures are modeled according to the nonlinear incremental dynamic analysis (IDA) procedure considering various frame configurations. Typical frames representing unbraced frames with masonry infill walls, braced frames with concentric bracings and braced frames with masonry infill walls were studied under the effect of 44 real ground motion records. Fragility curves were developed for these structures and the probability of exceedance at immediate occupancy (IO), life safety (LS) and collapse prevention (CP) performance limits was assessed for two seismic hazard scenarios (475 and 2475years return period). For the 2% probability of exceedance in 50years case, the probability of exceeding the CP performance limit is 90%, 74% and 56% for the 3-story structure consisting of unbraced frames with masonry infill, braced frames with concentric braces and braced frames with masonry infill, respectively. The corresponding values for the 5-story models are 94%, 69% and 62%. These alarming high values suggest that the seismic retrofit of such existing structures is of crucial importance.

Earthquake-induced rockfall hazard zoning

A methodology for quantitative probabilistic hazard zonation for earthquake-induced rockfalls is presented and demonstrated in the area of Friuli (Eastern Italian Alps) affected by the 1976 Mw 6.5 earthquake. Four rockfall datasets have been prepared both from historical data analysis and field surveys. The methodology relies on a three-dimensional hazard vector, whose components include the rockfall kinetic energy, the fly height, and the annual frequency. The values of the first two components are calculated for each location along the slope using the 3D rockfall runout simulator Hy-STONE. The rockfall annual frequency is assessed by multiplying the annual onset frequency by the simulated transit frequency. The annual onset frequency is calculated through a procedure that combines the extent of unstable areas, calculated for 10 different seismic-hazard scenarios with different annual frequencies of occurrence, and the magnitude relative–frequency relationship of blocks as derived from the collected field data. For each annual frequency of occurrence, the unstable area is calculated as a function of morphometric and earthquake characteristics. A series of discriminant-analysis models, using the rockfall datasets and DEMs of different resolution (1 and 10m), identified the controlling variables and verified the model robustness. In contrast with previously published relationships, we show that the slope curvature plays a relevant role in the computation of the unstable area.

The Greek Database of Seismogenic Sources (GreDaSS): state-of-the-art for northern Greece

The Greek Database of Seismogenic Sources (GreDaSS) is a repository of geological, tectonic and active-fault data for the Greek territory and its surroundings. In this report, we present the state-of-the-art of an on-going project devoted to the building of the GreDaSS, which represents the results of decades of investigations by the authors and a myriad of other researchers working on the active tectonics of the broader Aegean Region. The principal aim of this international project is to create a homogeneous framework of all of the data relevant to the seismotectonics, and especially the seismic hazard assessment, of Greece and its surroundings, as well as to provide a common research platform for performing seismic hazard analyses, modeling and scenarios from specific seismogenic structures. In particular, we introduce and synthetically describe the results obtained (and included in the database) to date in the northern sector of continental Greece and the Aegean Sea. As a first step we collected all available (both published and unpublished) historical and instrumental seismicity data relevant to the determining of the causative faults. Following the experience of recent 'surprising' earthquakes (e.g. 1995 Kozani, and 1999 Athens), we realized the deficiency of such an approach, and decided to also include in the GreDaSS active faults (i.e. seismogenic sources) recognized on the basis of geological, structural, morphotectonic, paleoseismological and geophysical investigations. A second step is the critical analysis of all of the collected data for the extraction of the necessary seismotectonic information, enabling the recognition of as many seismogenic sources as possible, as well as their characterization and parameterization. The most updated version of the database consists of numerous seismogenic sources that are categorized into three types: composite, individual, and debated. In this report, we describe the major seismotectonic properties of all of the composite seismogenic sources and individual seismogenic sources in northern Greece, which imply the partitioning of the area into five sectors that show similar internal behavior. Northern Greece was chosen as a pilot area because the parameters and accompanied metadata of its seismogenic sources show a high level of confidence and completeness. The amount of information and the degree of uncertainty is different for the three types.