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Kosovo is one of the most seismically active regions in Europe, lying within the Alpine-Mediterranean tectonic belt. Historical records for the region show several catastrophic earthquakes with epicentral intensity IX (MCS). However, due to Kosovo’s high population density, high prevalence of traditional construction, and insufficient enforcement of building codes, Kosovo is vulnerable to earthquake damage. In this study, we present earthquake hazard maps for bedrock conditions in Kosovo based on the well-known Neo-deterministic Seismic Hazard Assessment (NDSHA) method. NDSHA relies upon the fundamental physics of wave generation and propagation in complex geologic structures to generate realistic time series, used as input for the computation of several ground motion parameters, integrating the available knowledge of seismic history, seismogenic zones and morphostructural nodes. In accordance with continuum mechanics, the tensor nature of earthquake ground motion is preserved, producing realistic signals using structural models obtained by tomographic inversion and earthquake source information readily available in literature. Our maps are generally consistent with the observed intensity IX (MCS) and suggest that, in some instances, intensity X could be reached.

The procedure we developed, and applied to a few relevant cases, leads to the seismic verification of a building by: a) use of a scenario based neodeterministic approach (NDSHA) for the calculation of the seismic input, and b) control of the numerical modeling of an existing building, using free vibration measurements of the real structure. The key point of this approach is the strict collaboration, from the seismic input definition to the monitoring of the response of the building in the calculation phase, of the seismologist and the civil engineer. The vibrometry study allows the engineer to adjust the computational model in the direction suggested by the experimental result of a physical measurement. Once the model has been calibrated by vibrometric analysis, one can select in the design spectrum the proper range of periods of interest for the structure. Then, the realistic values of spectral acceleration, which include the appropriate amplification obtained through the modeling of a “scenario” input to be applied to the final model, can be selected. Generally, but not necessarily, the “scenario” spectra lead to higher accelerations than those deduced by taking the spectra from the national codes (i.e. NTC 2008, for Italy). The task of the verifier engineer is to act so that the solution of the verification is conservative and realistic. We show some examples of the application of the procedure to some relevant (e.g. schools) buildings of the Trieste Province. The adoption of the scenario input has given in most of the cases an increase of critical elements that have to be taken into account in the design of reinforcements. However, the higher cost associated with the increase of elements to reinforce is reasonable, especially considering the important reduction of the risk level.

Lessons learnt from the destructive earthquakes occurred during the new millennium provide new opportunities to take action, revise and improve the procedure for seismic hazard assessment. When dealing with cultural heritage and critical structures (e.g. nuclear power plants), where it is necessary to consider extremely long time intervals, the standard hazard estimates are by far unsuitable, due to their basic heuristic limitations. A viable alternative to traditional seismic hazard assessment is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance and faulting style, and by the treatment of complex source processes. The scenario-based methods (NDSHA) for seismic hazard analysis, where realistic and duly validated synthetic time series, accounting for source, propagation and site effects, are used to construct earthquake scenarios. The NDSHA procedure provides strong ground motion parameters based on the seismic waves propagation modeling at different scales accounting for a wide set of possible seismic sources and for the available information about structural models. Actually, the proposed method can be applied at regional (national) scale, computing seismograms at the nodes of a grid with the desired spacing, also integrated with time dependent scenarios, or at local (metropolitan) scale, taking into account detailed source characteristics, the path and local geological and geotechnical conditions by means of 3D laterally heterogeneous anelastic models. The relevance of the realistic modeling, which permits the generalization of empirical observations by means of physically sound theoretical considerations, is evident, as it allows for the optimization of the structural design with respect to the site of interest.

Lessons learnt from the destructive earthquakes occurred during the new millennium provide new opportunities to take action, revise, and improve the procedure for seismic hazard assessment (SHA). A single hazard map cannot meet the requirements from different end-users; the mapping of the expected earthquake ground motion that accounts for events’ recurrence may be suitable for insurances. When dealing with cultural heritage and critical structures (e.g., nuclear power plants), where it is necessary to consider extremely long time intervals, the standard hazard estimates are by far unsuitable, due to their basic heuristic limitations. While time-dependent SHA may be suitable to increase earthquake preparedness, by planning adequate mitigation actions, for critical structures (i.e., those for which the consequences of failure are intolerable) the maximum possible seismic input is relevant. Therefore the need for an appropriate estimate of the seismic hazard, aimed not only at the seismic classification of the national territory, but also at the capability of properly accounting for the local ampli␣cations of ground shaking, as well as for the fault properties, is a pressing concern for seismic engineers. A viable alternative to traditional SHA is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance, and faulting style, and by the treatment of complex source processes. The relevance of the realistic modeling, which permits the generalization of empirical observations by means of physically sound theoretical considerations, is evident, as it allows the optimization of the structural design with respect to the site of interest. The time information associated with the scenarios of ground motion, given by the intermediate-term middle-range earthquake predictions, can be useful to public authorities in assigning priorities for timely mitigation actions. Therefore, the approach we have developed naturally supplies realistic time series of ground motion useful to preserve urban settings, historical monuments, and relevant man-made structures.

Neo-deterministic seismic hazard assessment. Operational issues are a pressing concern in seismic hazard assessment (SHA), as fatally evidenced by the most destructive recent events worldwide, including the Tohoku (2011) and Haiti (2010) earthquakes (Wyss et al., 2012). A reliable and comprehensive characterization of expected seismic ground shaking, eventually including the related time information, is essential in order to develop effective mitigation strategies and to increase earthquake preparedness (Peresan et al., 2012). Nowadays it is well recognized by the engineering community that standard hazard indicator estimates (e.g. seismic PGA) alone are not sufficient for the adequate design, mainly for special buildings and infrastructures (Field et al., 2000; Zuccolo et al., 2008). Moreover, any effective tool for SHA must demonstrate its capability in anticipating the ground shaking related with large earthquake occurrences, a result that can be attained only through rigorous verification and validation process (Stein et al., 2011, 2012; Peresan and Panza, 2012).

For the protection of cultural heritage and the design of strategic buildings and critical infrastructures, when it is necessary to consider extremely long time intervals, the standard probabilistic estimates of seismic hazard (PSHA) are by far not applicable. The heuristic limitations are, indeed, a major limit of PSHA, whose results, extrapolating ground motion with an infinitely long return period from a few hundreds years of the available earthquake catalogues, may turn out to be a purely numerical artefact. A viable alternative, capable of minimizing the drawbacks of PSHA is represented by the use of a scenario-based methodology, named neo-deterministic approach (NDSHA), which relies on observable data and is based on the physical modelling of seismic waves generation and propagation processes. The NDSHA naturally supplies realistic time series of ground motion, which represent also reliable estimates of ground displacement readily applicable to seismic isolation techniques, useful to preserve historical monuments and relevant man made structures. In addition, an integrated NDSHA approach has been developed that allows for the operational definition of time-dependent scenarios of ground shaking, through the routine updating of formally defined earthquake predictions. The integrated NDSHA procedure, which is currently applied to the Italian territory, combines different pattern recognition techniques, designed for the space-time identification of strong earthquakes, with algorithms for the realistic modelling of ground motion. Accordingly, when an alarm is declared, a set of scenarios of expected ground shaking at bedrock, associated with the alarmed areas identified by means of the algorithms CN and M8S, can be readily computed by means of full waveform modelling, both at regional and local scale, considering all of the possible earthquake sources within the alerted areas. For the relevant sites, further investigations can be performed taking into account the local soil conditions, in order to compute the seismic input (realistic synthetic seismograms) for engineering analysis. The practical application of seismic input modelling for seismic isolation purposes, and particularly for the protection of historical buildings, has been already carried out for example for several sites, including the cities of Trieste (NE Italy) and Valparaiso (Chile) and the towns of Marigliano and Ercolano (Naples, Italy). A recent example of the practical advantages that can be provided by the time-dependent definition of ground-shaking scenarios is given by the Cathedral of Santa Maria di Collemaggio, which was severely damaged during the L’Aquila earthquake (6 April 2009). Based on the ongoing alert for the nearby CN region and the relevant ground shaking expected at the site, the restoration and isolation of the cathedral could have been timely completed, possibly limiting if not preventing the occurred damage. The relevance of the realistic modelling, which permits the generalization of empirical observations by means of physically sound theoretical considerations, is evident, as it allows for the optimisation of the structural design with respect to the site of interest. Moreover, the time information given by the intermediate-term middle-range earthquake prediction can enhance preparedness and planning of risk mitigation actions.

A seismic hazard map of the territory of India and adjacent areas has been prepared using a deterministic approach based on the computation of synthetic seismograms complete with all main phases. The input data set consists of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. There are few probabilistic hazard maps available for the Indian subcontinent, however, this is the first study aimed at producing a deterministic seismic hazard map for the Indian region using realistic strong ground motion modelling with the knowledge of the physical process of earthquake generation, the level of seismicity and wave propagation in anelastic media. Synthetic seismograms at a frequency of 1 Hz have been generated at a regular grid of 0.2◦ × 0.2◦ by the modal summation technique. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (V max), and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory. The estimated values of the peak ground acceleration are compared with the observed data available for the Himalayan region and are found to be in agreement. Many parts of the Himalayan region have DGA values exceeding 0.6 g. The epicentral areas of the great Assam earthquakes of 1897 and 1950 in northeast India represent the maximum hazard with DGA values reaching 1.2–1.3 g. The peak velocity and displacement in the same region is estimated as 120–177 cm s−1 and 60–90 cm, respectively.

The earthquake record and the Code for design and construction in seismic regions in Bulgaria have shown that the territory of the Republic of Bulgaria is exposed to a high seismic risk due to local shallow and regional strong intermediate‐depth seismic sources. The available strong motion database is quite limited, and therefore not representative at all of the real hazard. The application of the neo‐deterministic seismic hazard assessment procedure for two main Bulgarian cities has been capable to supply a significant database of synthetic strong motions for the target sites, applicable for earthquake engineering purposes. The main advantage of the applied deterministic procedure is the possibility to take simultaneously and correctly into consideration the contribution to the earthquake ground motion at the target sites of the seismic source and of the seismic wave propagation in the crossed media. We discuss in this study the result of some recent applications of the neo‐deterministic seismic microzonation procedure to the cities of Sofia and Russe. The validation of the theoretically modeled seismic input against Eurocode 8 and the few available records at these sites is discussed.

The preliminary regional seismic hazard map for Pakistan and adjoining regions published by Sarwar et al. (2018) is here updated. The earthquake catalog by Khan et al. (2018) is adopted, and the latest computer codes for the neo-deterministic seismic hazard assessment (NDSHA) are used. At the regional scale, NDSHA is based on the generation of synthetic seismograms at a regular grid of 0.2 degrees × 0.2 degrees. The main input is a set of earthquake sources and layered anelastic structural models. As a result, seismic hazard maps are produced in terms of maximum displacement (Dmax), maximum velocity (Vmax), and design ground acceleration. The comparison between probabilistic (PSHA) and NDSHA maps for Pakistan shows that the currently adopted PSHA maps generally underestimate the level of ground shaking that might be expected for future events.

The Suez Canal Economic Zone (SCZone) is a mega project in Egypt that was launched to increase the role of the Suez Canal region in international trading and to develop the urbanization of the region. The reliable assessment of seismic hazard is a crucial input information for the designer and planner of all projects in this area. In this study, an updated seismic hazard map for Suez Canal region that incorporates revised historical earthquake catalogs, morphostructural zonation data (MZ), revised focal mechanism solutions and mechanical models of the lithospheric structure is provided. This is done within the framework of the Neo-Deterministic Seismic Hazard Assessment (NDSHA) procedure that may efficiently incorporate earthquake source rupture data, geological information and any reliable new information to adequately compute the earthquake ground motion maps, like PGA, PGV and PGD. This methodology provides a comprehensive source of ground motion records (acceleration, velocity, displacement) for Egypt where a substantial challenge is posed by the lack of recorded data. To consistently assess the uncertainty of our understanding of the seismic hazard and its effect on critical structures a sensitivity analysis is performed varying, for example, (a) source focal mechanism, (b) directivity (c) rupture process and (d) seismotectonic model. Starting from the initial definition of the source, bedrock and site properties based on the available knowledge of the characteristics of the different earthquake scenarios and of the soil structural properties of the area deduced from the ambient noise array measurements, a set of ground shaking scenarios have been computed at the selected profile crossing the Suez Canal. Variations of the ground shaking scenarios are evaluated looking basically at: (a) the amplitudes measured on the waveforms and the response spectra, (b) the changes in the shaking duration and (c) the modifications in the amplification patterns. Finally, the seismic input (e.g. response spectra, time histories) at the tunnel site that undergoes the Suez Canal to connect Sinai peninsula with the western side of the country is provided.

The neo-deterministic seismic hazard assessment (NDSHA), developed at the University of Trieste (UT), has emerged as an attractive tool for predicting the ground motion for given seismic sources and known earth structure. This method, a computationally intensive procedure, is based on physical modeling of wave propagation and seismic source process. Under ongoing research and academic collaboration program between UT and BUET, NDSHA studies have been performed for Bangladesh. This chapter briefly presents significant results obtained under this initiative. Results obtained are compared with the seismic zoning map in the updated Bangladesh National Building Code (BNBC-2020). The seismicity and seismo-tectonics of Bangladesh and the adjoining region are also briefly discussed.

Many devastating earthquakes inflicted heavy casualties and property losses in the seismically active China Seismic Experimental Site area (CSES: 97.5° ~ 105.5°E, 21° ~ 32°N). We performed a first-order seismic zoning based on Neo-deterministic Seismic Hazard Assessment (NDSHA) in the study area delimited by 94° ~ 108°E and 19° ~ 35°N, containing the South-East margin of the Tibetan Plateau and the Sichuan-Yunnan region. The seismic hazard is expressed by maps of peak ground displacement (PGD), peak ground velocity (PGV) and design ground acceleration (DGA) values, extracted from synthetic seismograms computed at a regional scale and mapped on a regular grid of 0.2° × 0.2° over the study area. For the computation of synthetic seismograms, we considered and updated all the available geophysical-geological-tectonic information, including historical and instrumental earthquake catalogues, seismogenic zones, seismogenic nodes, focal mechanisms, and geophysical structural models. We tested the performance of our assessments with available data (i.e., after the Great Wenchuan (2008, May 12th, Ms = 8.0) and Lushan (2013, April 20th, Ms = 7.0) earthquakes) and verified the negligible influence of large events located “far” from the study area. The results indicate the high seismic hazard of the region, with a particular attention (i.e., where DGA > 0.6 g) to the areas located around the main fault zones, e.g., the Longmenshan, Anninghe and Zemuhe Fault Zones. These first-order NDSHA zoning findings may serve as a knowledge basis to support both large- to mid-range preparedness actions and (multi-scenario) site-specific studies.

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reli- able and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489–508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93–165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489–508, 2003): the computer codes were improved to better fit the need of producing real- istic ground shaking maps and ground shaking scenar- ios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.

Ischia island, in the province of Naples, is a densely populated volcanic island, in which small to moderate magnitude earthquakes occur. Due to the very shallowdepth of such events (< 2 km), they can generate serious damage and casualties, up to the complete destruction of urban centers located within short epicentraldistance. Almost all of the earthquakes at Ischia island occur at shallow depth, beneath the Northern slopes of the Mt. Epomeo horst, which is located very close to thetown of Casamicciola. In fact, Casamicciola was completely destroyed by the 1883 earthquake (2313 victims) and experienced intensities up to XI degree on theMercalli scale. Historical records show that the background seismicity here is almost absent, but larger earthquakes tend to occur in clusters, lasting some decadesand with intervals between consecutive events on the order of years to decades. The clustering in time and the very shallow hypocentres, which cause, with respect totectonic earthquakes of similar magnitude, larger effects though limited to a relatively small area, make the seismicity in this island very peculiar. Despite suchdestructive record, till now official hazard maps strongly underestimated the seismic hazard in this area. On August 21st 2017, a very shallow earthquake with rathersmall magnitude struck the area of Casamicciola, killing two people, injuring many more and causing huge damage and partial to total collapse of edifices located justabove the earthquake fault.The maximum acceleration recorded for this earthquake exceeded by more than a factor of two the reference acceleration that should be sustained by edifices,according to official hazard maps. We propose here a complete procedure to assess and mitigate the risk, which can be rapid and economically affordable and, at thesame time, can avoid further grief due to possible occurrence of other destructive earthquakes within a short time interval. We describe the most likely buildingcollapse and casualty scenarios, in case that low-to-moderate magnitude earthquakes would occur before the edifices would be appropriately reinforced and secured.Our scenarios demonstrate the urgent need for securing operations. The proposed procedures for assessing seismic hazard and for securing urban areas provide anexample that is potentially applicable to the whole Italian peninsula. They may allow in fact the mitigation of the destructive impact of a large number of earth-quakes, which in Italy are often characterized by low or moderate magnitudes.

The Neo-Deterministic Seismic Hazard Assessment (NDSHA) procedure for the development of seismic hazard maps at the regional scale has been validated by all the events occurred in regions where NDSHA maps were available at the time of the quake. NDSHA method reliably and realistically simulates the wide suite of earthquake ground motions that may impact civil populations as well as their heritage buildings. The scenario based NDSHA’s modeling technique is developed from comprehensive physical knowledge of: (i) the seismic source process; (ii) the propagation of earthquake waves; and (iii) their combined interactions with site effects. A useful safety factor conceptually similar to the ones used in structural engineering can be used to set the estimated magnitude of the scenario events. Using the signals generated by NDSHA, well rooted on the fundamental laws of physics and on the experimental evidence, a number of possible structural engineering approaches become available.

Throughout time, the area of historical Cairo has been affected by several earthquakes from near and distant seismogenic zones. The maximum earthquake intensity reported in Cairo is VII, on the Modified Mercalli Intensity scale, due to the 1992 Cairo earthquake (Mw=5.9). About 212 Coptic and Islamic monuments were damaged. The spatial distribution of damage, suggests the occurrence of strong local site effects in combination with high vulnerability of the cultural heritage buildings. This study presents the application of a novel seismic hazard analysis approach at a local scale based on physics-based ground motion simulations. A site-specific multi-scenario seismic input (ground motion time histories and response spectra) is computed at a heritage building in Cairo, considering the local site effect. The seismic input is calculated in three steps: a regional scale analysis followed by a site-specific analysis and the combinations of the computed scenarios ground motion. In the regional scale analysis synthetic accelerograms are computed at the site bedrock. Then, the site-specific analysis is performed to calculate the site surface ground motions or response spectra considering the local site effect. Three earthquake scenarios have been considered, characterized by different locations, magnitudes, and fault configurations. The last step consists in the combination of the computed scenario ground motion into one single multi-scenario seismic input specific for the site of interest. This input is represented by spectral ordinates and their variability. For the engineering purpose of time history analysis, the method allows also to extract the computed site specific physics-based accelerograms, requiring no amplitude scaling nor filtering by magnitudes, distances, or site classifications, as usually done with real ground motion records.

Seismic hazard maps for Alborz region (north of Iran) and adjacent areas are prepared using the neo-deterministic seismic hazard assessment (NDSHA) based on the computation of synthetic seismograms at the regional scale. The study area is zoned according to different geophysical structural models delimited at the surface by polygons, used to define the mechanical properties of the source-site paths. We have refined the velocity structures of Iran, as obtained from surface waves tomography, to obtain the velocity structure of Alborz region by applying the joint inversion of the P-wave receiver functions (PRF) and surface wave's dispersion. The input data set consists of attenuation-velocity structural models (representing bedrock conditions), seismogenic zones, focal mechanisms and the catalog of past seismicity. The seismic hazard, expressed in terms of maximum displacement (PGD), maximum velocity (PGV) and design ground acceleration (DGA), is extracted from the synthetic seismograms and mapped on a regular grid of 0.2° × 0.2° over the entire region. The results of this first order NDSHA zoning indicate a high seismic hazard in the Alborz region and may represent an important knowledge basis towards detailed and comprehensive seismic microzonation studies.

The aim of this work is two-fold: 1) to compare the results of national scale NDSHA modelling for the Italian region at 10 Hz cut-off, based on the relevant available knowledge, with observations (e.g., peak ground motion values) and existing empirical attenuation relations; 2) to update the scaling law for source spectra (SLSS) to be used for the selected area. The new set of source spectra, defined along the lines suggested by the comparison with empirical attenuation relations, produces acceptable results in terms of PGV and spectral acceleration at long periods. Synthetic PGA and SA at short periods show a faster attenuation with respect to the observed ones and, therefore, the effect of complex attenuation factors should be explored in future ad hoc studies.

A web application prototype is described, aimed at the generation of synthetic seismograms for user-defined earthquake models. The web application graphical user interface hides the complexity of the underlying computational engine, which is the outcome of the continuous evolution of sophisticated computer codes, some of which saw the light back in the middle 1980s. With the web application, even the non-experts can produce ground shaking scenarios at the local or regional scale in very short times, depending on the complexity of the adopted source and medium models, without the need of a deep knowledge of the physics of the earthquake phenomenon. Actually, it may even allow neophytes to get some basic education in the field of seismology and seismic engineering, due to the simplified intuitive experimental approach to the matter. One of the most powerful features made available to the users is indeed the capability of executing quick parametric tests in near real-time, to explore the relations between each model’s parameter and the resulting ground motion scenario. The synthetic seismograms generated through the web application can be used by civil engineers for the design of new seismo-resistant structures, or to analyse the performance of the existing ones under seismic load.

This paper describes the outcome of the advanced seismic hazard and seismic risk estimates recently performed for the city of Sofia, based on the state-of-the-art of knowledge for this site. Some major results of the neo-deterministic, scenario-based, seismic hazard assessment approach (NDSHA) to the earthquake hazard assessment for the city of Sofia are considered. Further validations of the recently constructed synthetic strong motion database, containing site and seismic source-specific ground motion time histories are performed and discussed. Displacement and acceleration response spectra are considered. The elastic displacement response spectra and displacement demand are discussed with regard to earthquake magnitude, seismic source-to-site distance, seismic source mechanism, and local geological site conditions. The elastic response design spectrum from the standard pseudo-acceleration, versus natural period, T n, format, converted to a capacity diagram in S a − S d format is discussed in the perspective of the Eurocode 8 provisions. A brief overview of the engineering applications of the seismic demand obtained making use of the NDSHA is supplied. Some applications of the outcome of NDSHA procedure for engineering purposes are shown. The obtained database of ground shaking waveforms and time-histories, computed for city of Sofia is used to: (1) extract maximum particle velocities; (2) calculate the space distribution of the horizontal strain factor Log10 e; (3) estimate liquefaction susceptibility in terms of standard penetration test, N values, and initial over burden stress; (4) estimate damage index distribution; and (5) map the distribution of the expected pipe breaks and red-tagged buildings for given scenario earthquakes, etc. The theoretically obtained database, based on the simultaneous treatment of the data from many disciplines, contains data fully suitable for practical use. The proper use of this database can lead to a significant seismic vulnerability reduction and thus contributes to earthquake preparedness.

Seismic hazard assessment can be performed following a neo-deterministic approach (NDSHA), which allows to give a realistic description of the seismic ground motion due to an earthquake of given distance and magnitude. The approach is based on modelling techniques that have been developed from a detailed knowledge of both the seismic source process and the propagation of seismic waves. This permits us to define a set of earthquake scenarios and to simulate the associated synthetic signals without having to wait for a strong event to occur. NDSHA can be applied at the regional scale, computing seismograms at the nodes of a grid with the desired spacing, or at the local scale, taking into account the source characteristics, the path and local geological and geotechnical conditions. Synthetic signals can be produced in a short time and at a very low cost/benefit ratio. They can be used as seismic input in subsequent engineering analyses aimed at the computation of the full non-linear seismic response of the structure or simply the earthquake damaging potential. Massive parametric tests, to explore the influence not only of deterministic source parameters and structural models but also of random properties of the same source model, enable realistic estimate of seismic hazard and their uncertainty. This is particular true in those areas for which scarce (or no) historical or instrumental information is available. Here we describe the implementation of the seismological codes and the results of some parametric tests performed using the EU-India Grid infrastructure.

SUMMARY The regional seismic hazard in Egypt is assessed using a deterministic approach based on the computation of synthetic seismograms at a set of gridpoints located at distances of 0.2u from each other. The main input for this computation are earthquake sources and structural models. The earthquake sources are parametrized using focal mechanisms, seismogenic areas and regional seismicity. A number of deep seismic profiles have been used to define the crustal structures. Similar sets of gravity profiles have been used to define the density of the layers. The peak displacement (DMAX), peak velocity (VMAX) and design ground acceleration (DGA) are chosen and plotted to construct the seismic hazard maps. There are similarities between computed and observed amplitudes of ground motion in terms of their values and spatial distributions. The results obtained from the deterministic and probabilistic approaches are comparable. The areas of high seismic hazard level are of great socio-economic importance.

Some of the elements of regional seismic hazard in Croatia are assessed by computing synthetic accelerograms at a predetermined set of sites. The input dataset consists of structural models, parameters of seismic sources, and an updated earthquake catalog. Synthetic strong-motion time series for frequencies below 1 Hz are computed on a grid of sites using the modal summation technique. The long-period hazard is described by the distribution of estimated peak values of ground displacement, velocity and acceleration, while the short-period hazard is represented by the map of design ground acceleration values (DGA). The highest values of DGA exceeding 0.35 g on the base-rock level are found in the southeastern coastal part of the country, in the greater Dubrovnik area.

—A deterministic seismic zoning of Cuba is performed by modelling, with modal summation, the complete P-SV and SH waves fields generated by point-source earthquakes buried in flat-layered anelastic media. The results of the computation, performed for periods greater than 1 second, are presented in two sets of maps of maximum displacement (d max), maximum velocity (v max) and design ground acceleration (DGA), obtained by using two different criteria in the definition of the input magnitude: (1) values reported in the earthquake catalogue (M obs) and (2) values determined from seismotectonic considerations (M max). A comparison with the results of a previous probabilistic seismic zoning is made to test the possibility of making intensity — ground motion conversion with the aid of log-linear regressions.

North Africa is one of the most earthquake-prone areas of the Mediterranean. Many devastating earthquakes, some of them tsunami-triggering, inflicted heavy loss of life and considerable economic damage to the region. In order to mitigate the destructive impact of the earthquakes, the regional seismic hazard in North Africa is assessed using the neo-deterministic, multi-scenario methodology (NDSHA) based on the computation of synthetic seismograms, using the modal summation technique, at a regular grid of 0.2 × 0.2°. This is the first study aimed at producing NDSHA maps of North Africa including five countries: Morocco, Algeria, Tunisia, Libya, and Egypt. The key input data for the NDSHA algorithm are earthquake sources, seismotectonic zonation, and structural models. In the preparation of the input data, it has been really important to go beyond the national borders and to adopt a coherent strategy all over the area. Thanks to the collaborative efforts of the teams involved, it has been possible to properly merge the earthquake catalogues available for each country to define with homogeneous criteria the seismogenic zones, the characteristic focal mechanism associated with each of them, and the structural models used to model wave propagation from the sources to the sites. As a result, reliable seismic hazard maps are produced in terms of maximum displacement (D max), maximum velocity (V max), and design ground acceleration.

An innovative approach to seismic hazard assessment is illustrated that, based on the available knowledge of the physical properties of the Earth structure and of seismic sources, on geodetic observations, as well as on the geophysical forward modeling, allows for a time-dependent definition of the seismic input. According to the proposed approach, a fully formalized system integrating Earth Observation data and new advanced methods in seismological and geophysical data analysis is currently under development in the framework of the Pilot Project SISMA, funded by the Italian Space Agency. The synergic use of geodetic Earth Observation data (EO) and Geophysical Forward Modeling deformation maps at the national scale complements the space- and time-dependent information provided by real-time monitoring of seismic flow (performed by means of the earthquake prediction algorithms CN and M8S) and permits the identification and routine updating of alerted areas. At the local spatial scale (tens of km) of the seismogenic nodes identified by pattern-recognition analysis, both GNSS (Global Navigation Satellite System) and SAR (Synthetic Aperture Radar) techniques, coupled with expressly developed models for interseismic phase, allow us to retrieve the deformation style and stress evolution within the seismogenic areas. The displacement fields obtained from EO data provide the input for the geophysical modeling, which eventually permits to indicate whether a specific fault is in a “critical state.” The scenarios of expected ground motion (shakemaps) associated with the alerted areas are then defined by means of full waveforms modeling, based on the possibility to compute synthetic seismograms by the modal summation technique (neo-deterministic hazard assessment). In this way, a set of deterministic scenarios of ground motion, which refer to the time interval when a strong event is likely to occur within the alerted area, can be defined both at national and at local scale. The considered integrated approach opens new routes in understanding the dynamics of fault zones as well as in modeling the expected ground motion. The SISMA system, in fact, provides tools for establishing warning criteria based on deterministic and rigorous forward geophysical models and hence allows for a well-controlled real-time prospective testing and validation of the proposed methodology over the Italian territory. The proposed approach complements the traditional probabilistic approach for seismic hazard estimates, since it supplies routinely updated information useful in assigning priorities for timely mitigation actions and hence it is particularly relevant to Civil Defense purposes.

An effective strategy for the seismic risk mitigation needs the use of advanced seismological methodologies for a realistic estimate of the seismic hazard and, consequently, to reduce earthquake damage through a preventive evaluation of vulnerability and actions for structure safety. Prediction of earthquakes and their related effects (expressed in terms of ground shaking) can be performed either by a probabilistic approach or by using modelling tools based, on one hand, on the theoretical knowledge of the physics of the seismic source and of wave propagation and, on the other hand, on the rich database of geological, tectonic, historical information already available. Strong earthquakes are very rare phenomena and it is therefore statistically very difficult to assemble a representative database of recorded strong motion signals that could be analyzed to define ground motion parameters suitable for seismic hazard estimations. That is, the probabilistic estimation of the seismic hazard is a very gross approximation, and often a severe underestimation, of reality. A realistic and reliable estimate of the expected ground motion can be performed by using the Neo-Deterministic Seismic Hazard Analysis (NDSHA), an innovative modelling technique that takes into account source, propagation and local site effects (for a recent review see Panza et al., 2011). This is done using basic principles of physics about wave generation and propagation in complex media, and does not require to resort to convolutive approaches, that have been proven to be quite unreliable, mainly when dealing with complex geological structures, the most interesting from the practical point of view. The NDSHA approach has been used, among others, in the framework of the UNESCOIUGS-IGCP project 414 "Seismic Ground Motion in Large Urban Areas", to evaluate ground motion of a group of Large Urban Areas and Megacities in the world representative of a broad spectrum of seismic hazard severity (Panza et al., 2004). A MW 6.3 earthquake struck on 6 April 2009, at 01.32 GMT, the Abruzzo region (central Italy). The L’Aquila town, located few km northeast to the main shock epicentre, and several villages located nearby, suffered heavy damages and the casualties were about 300. The damage level generally corresponded to intensity ≤ VIII MCS, with few maximum values ≥

Estimates of seismic hazard obtained using the neo-deterministic approach (NDSHA) and the probabilistic approach (PSHA) are compared for the Italian territory. The NDSHA provides values larger than those given by the PSHA in areas where large earthquakes are observed and in areas identified as prone to large earthquakes, but lower values in low-seismicity areas. These differences suggest the adoption of the flexible, robust and physically sound NDSHA approach to overcome the proven shortcomings of PSHA, thus allowing for a reliable seismic hazard estimation, especially for those areas characterized by a prolonged quiescence, i.e. in tectonically active sites where events of only moderate size have occurred in historical times.

An integrated neo-deterministic approach to seismic hazard assessment has been developed that combines different pattern recognition techniques, designed for the space–time iden- tification of impending strong earthquakes, with algorithms for the realistic modeling of seismic ground motion. The integrated approach allows for a time-dependent definition of the seismic input, through the routine updating of earthquake predictions. The scenarios of expected ground motion, associated with the alarmed areas, are defined by means of full waveform modeling. A set of neo-deterministic scenarios of ground motion is defined at regional and local scales, thus providing a prioritization tool for timely preparedness and mitigation actions. Constraints about the space and time of occurrence of the impending strong earthquakes are provided by three formally defined and globally tested algorithms, which have been developed according to a pattern recognition scheme. Two algorithms, namely CN and M8, are routinely used for intermediate-term middle-range earthquake predictions, while a third algorithm allows for the identification of the areas prone to large events. These independent procedures have been combined to better constrain the alarmed area. The pattern recognition of earthquake-prone areas does not belong to the family of earthquake prediction algorithms since it does not provide any information about the time of occurrence of the expected earthquakes. Never- theless, it can be considered as the termless zero-approximation, which restrains the alerted areas (e.g. defined by CN or M8) to the more precise potential location of large events. Italy is the only region of moderate seismic activity where the two different pre- diction algorithms, CN and M8S (i.e. a spatially stabilized variant of M8), are applied simultaneously and a real-time test of predic- tions, for earthquakes with magnitude larger than a given threshold (namely 5.4 and 5.6 for CN algorithm, and 5.5 for M8S algorithm) has been ongoing since 2003. The application of the CN to the Adriatic region, which is relevant for seismic hazard assessment in the northeastern part of the Italian territory, is also discussed. Examples of neo-deterministic scenarios are provided, at regional and local scale and for the cities of Trieste and Nimis (Friuli Venezia Giulia region), where the knowledge of the local geological conditions permitted a detailed evaluation of the expected ground motion.

Detailed Vs profiles with Depth can be obtained in urban areas from the nonlinear inversion with hedgehog method of the Raileigh waves group velocity dispersion curves of the fundamental mode extracted with the FTAN method from the recorded signal of active seismic experiments at a single station. Recently, the approach has been applied to cross correlations of long time series of ambient seismic noise as they have been demonstrated to recover surface wave dispersion (Green function) over a broad range of distances. We present some examples of FTAN measurements, for both active and passive experiments, performed in the highly noisy urban area of Napoli, with the definition of Vs profiles to depths of 2 km. Such examples aim to show the successful application of the proposed approach for the mitigation of both seismic and volcanic risk in that stratigraphies, blind because of unaccessible outcrops in densely urbanized areas, can be reliably reconstructed.

a r t i c l e i n f o A good knowledge of shear wave (V s ) structural models is required for the realistic modelling of seismic hazard scenarios. Nowadays there are many approaches based on surface wave dispersion evaluation, mainly oriented to the use of controlled source techniques with appropriate shot gathers. Subsoil deep controlled source surveys suffer great logistic problems and costs, due to the amount of source energy they need (e.g. explosive). Otherwise realistic seismic motion evaluation requires the knowledge of V s structural models even at large depths (e.g. 100-200 m). In this work we use the cross correlation of seismic noise in order to evaluate surface wave dispersion in a passive way, without controlled sources. Cross correlation of seismic noise recordings can be used to infer the impulse response between two points when the so-called noise correlation function (NCF) converges to the impulse response between two receivers,!ltered by the bandwidth of the noise spectrum. The NCF between two noise recording sensors could be in such a way considered as the passive analogous to a shot gather made with active sources in the space between the sensors themselves. In this work we computed the NCF between two sensors using both sea source noise and an anthropic noise source (an airport), in order to infer a V s structural model pro!le in an area of the Venice Plain (North-East Italy). Rayleigh wave fundamental mode dispersion curve has been extracted from NCF using the Frequency Time Analysis (FTAN) method. The results of the non-linear inversion of dispersion data, in terms of 1D V s distribution versus depth, are consistent with the geological subsoil conditions of the studied area and represent the!rst shear wave velocities middle deep characterisation of the Venetian hinterland.

The seismic ground motion of the greater Accra Metropolitan Area has been modelled for land use planning and disaster mitigation. The deterministic computation, a hybrid method based on the modal summation and finite difference method was used. Using these techniques, the seismic ground motion along four profiles located in the metropolis has been computed. The 1939 earthquake of magnitude 6.5 (ML ) was used as the scenario earthquake. Synthetic seismic waveforms from which parameters for engineering design such as peak ground acceleration, velocity and spectral amplifications have been produced along the geological cross sections. The peak ground acceleration and velocity computed for the metropolis ranges from 0.14 g to 0.57 g and 9.2 cms−1 to 37.1 cms−1, respectively. These correspond to intensity ranging from VII to IX on the Modified Mercalli Intensity scale. Areas in the metropolis underlain by unconsolidated sediments experience the largest shakings. The results illustrated represent a useful guide for civil engineers in the design of buildings in the metropolis for safe and sustainable development.

A review of the recent achievements of the innovative neo-deterministic approach for seismic hazard assessment through realistic earthquake scenarios has been performed. The procedure provides strong ground motion parameters for the purpose of earthquake engineering, based on the deterministic seismic wave propagation modelling at different scales— regional, national and metropolitan. The main advantage of this neo-deterministic procedure is the simultaneous treatment of the contribution of the earthquake source and seismic wave propagation media to the strong motion at the target site/region, as required by basic physical principles. The neo-deterministic seismic microzonation procedure has been successfully applied to numerous metropolitan areas all over the world in the framework of several international projects. In this study some examples focused on CEI region concerning both regional seismic hazard assessment and seismic microzonation of the selected metropolitan areas are shown.

The city of Sofia has the densest population of Bulgaria – around 1.27 million people. The capital is exposed to high seismic risk. According to the Bulgarian seis- mic code, Sofia has been included in a seismic category characterized by intensity IX (MSK), which corresponds to a horizontal acceleration of 0.27 g for the anchoring of the elastic response spectrum. Because of the lack of instrumental seismic data, real- istic synthetic strong motion waveforms for two opposite positions of seismic sources, have been generated for an expected earthquake scenarios (M = 7) along three ge- ological profiles. A hybrid modeling method has been used for the modeling, which is based on the modal summation technique and finite difference scheme. The calcu- lation has been done using an extended source model. The site effect is represented in terms of response spectra ratio (RSR), with respect to a bedrock model. The three components synthetic seismograms, computed in the domain of displacement, velocity and acceleration have been processed to extract some parameters very useful for engineering applications.

The capital of Bulgaria, Sofia is a growing city with population around 1.22 million. The city is exposed to a high seismic risk since it is placed in the centre of Sofia seismic area. Over the centuries in the town of Sofia the macroseismic intensities have been larger than IX (MSK). A study of the site effects and the microzonation of a part of metropolitan Sofia, based on a modelling of seismic ground motion along three cross sections are presented. Realistic synthetic strong motion waveforms have been computed for an expected scenario earthquake (M=7) applying a hybrid modelling method, based on the modal summation technique and finite differences scheme. The site amplification is determined in terms of response spectra ratio (RSR). A set of time histories and quantities of earthquake engineering interest are supplied, that allow the definition of six zones characterized by specific response spectra. The results from this study constitute a “database” that describes the ground shaking of the urban area. The synthetic velocigrams are employed to calculate the distribution of the horizontal strain factor Log10e using a simplified relation between particle velocity and velocity of shear waves in the surface layer. It is shown that it is possible to estimate liquefaction susceptibility in terms of standard penetration tests (SPT), Nvalues and initial over burden stress. Using the data for maximum particle velocity and empirical relationships developed from the Northridge earthquake, 1994 the distributions of the expected pipe breaks and red-tagged buildings for Sofia city are shown.

The project addressed the problem of pre-disaster orien- tation: hazard prediction, risk assessment, and hazard mapping, in connection with seismic activity and man- induced vibrations. The definition of realistic seismic input has been obtained from the computation of a wide set of time histories and spectral information, corre- sponding to possible seismotectonic scenarios for dif- ferent source and structural models. The innovative modeling technique, that constitutes the common tool to the entire project, takes into account source, propaga- tion and local site effects. This is done using first princi- ples of physics about wave generation and propagation in complex media, and does not require to resort to con- volutive approaches, that have been proven to be quite unreliable, mainly when dealing with complex geologi- cal structures, the most interesting from the practical point of view. In fact, several techniques that have been proposed to empirically estimate the site effects using observations convolved with theoretically computed signals corresponding to simplified models, supply reli- able information about the site response to non-interfer- ing seismic phases. They are not adequate in most of the real cases, when the seismic sequel is formed by several interfering waves. The availability of realistic numeri- cal simulations enables us to reliably estimate the amplification effects even in complex geological struc- tures, exploiting the available geotechnical, lithologi- cal, geophysical parameters, topography of the medium, tectonic, historical, palaeoseismological data, and seismotectonic models. The realistic modeling of the ground motion is a very important base of knowl- edge for the preparation of groundshaking scenarios that represent a valid and economic tool for the seismic microzonation. This knowledge can be very fruitfully used by civil engineers in the design of new seismo- resistant constructions and in the reinforcement of the existing built environment, and, therefore, supply a par- ticularly powerful tool for the prevention aspects of Civil Defense. We present a selection of the main results obtained for the cities of Algiers, Beijing, Bucharest, Cairo, Debrecen, Delhi, Naples, Rome, Russe, Santiago de Cuba, Sofia, Thessaloniki and Zagreb.

— The city of Sofia is exposed to a high seismic risk. Macroseismic intensities in the range of VIII – X (MSK) can be expected in the city. The earthquakes that can influence the hazard in Sofia originate either beneath the city or are caused by seismic sources located within a radius of 40 km. The city of Sofia is also prone to the remote Vrancea seismic zone in Romania, and particularly vulnerable are the long-period elements of the built environment. The high seismic risk and the lack of instrumental recordings of the regional seismicity make the use of appropriate credible earthquake scenarios and ground-motion modelling approaches for defining the seismic input for the city of Sofia necessary. Complete synthetic seismic signals, due to several earthquake scenarios, were computed along chosen geological profiles crossing the city, applying a hybrid technique, which combines the modal summation technique and finite differences. The modelling takes into account simultaneously the geotechnical properties of the site, the position and geometry of the seismic source and the mechanical properties of the propagation medium. Acceleration, velocity and displacement time histories and related quantities of earthquake engineering interest (e.g., response spectra, ground-motion amplification along the profiles) have been supplied. The approach applied in this study allows us to obtain the definition of the seismic input at low cost, exploiting large quantities of existing data (e.g. geotechnical, geological, seismological). It may be efficiently used to estimate the ground motion for the purposes of microzonation, urban planning, retrofitting or insurance of the built environment, etc.