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Earthquake ground motion is a natural phenomenon associ- ated with a sudden release of energy due to a fault rupture. Strong-motion seismology deals with seismic waves radiated by large earthquakes. More precisely, it is concerned with measurement, interpretation and prediction of strong shaking generated by damaging earthquakes. Because of the engineering need for estimates of future strong-ground motion, the scope of strong-motion seismol- ogy encompasses seismic source theory and all other aspects of seismology that can provide insights helpful in making the best possible earthquake ground-shaking scenarios given the limited observational data.

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.

A reliable and comprehensive characterization of expected seismic ground shaking is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. So far, one of the major problems in classical methods for seismic hazard assessment consisted in the adequate characterization of the attenuation models, which may be unable to account for the complexity of the medium and of the seismic sources and are often weakly constrained by the available observations. Current computational resources and physical knowledge of the seismic waves generation and propagation processes allow nowadays for viable numerical and analytical alternatives to the use of attenuation relations. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic approach (NDSHA), which allows considering a wide range of possible seismic sources as the starting point for deriving scenarios by means of full waveforms modelling. The method does not make use of attenuation relations and, thanks to advanced computational infrastructures, permits to carry on parametric analysis and stability tests that contribute characterizing the related uncertainties, as well as to fill in the unavoidable gaps in available observations. Results from preliminary application of NDSHA method to regional scale seismic hazard assessment (ground motion at bedrock) and tsunami scenarios modelling for the Gujarat territory are illustrated. The resulting estimates are compared with available information about intensities from past earthquakes, as well as with recently developed probabilistic seismic hazard map of Gujarat.