No abstract

This article describes the Engineering Strong-Motion Database (ESM), developed in the framework of the European project Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation (NERA, see Data and Resources). ESM is specifically designed to provide end users only with quality-checked, uniformly processed strong-motion data and relevant parameters and has done so since 1969 in the Euro-Mediterranean region. The database was designed for a large variety of stakeholders (expert seismologists, earthquake engineers, students, and professionals) with a user-friendly and straightforward web interface. Users can access earthquake and station information and download waveforms of events with magnitude ≥ 4:0 (unprocessed and processed acceleration, velocity, and displacement, and acceleration and displacement response spectra at 5% damping). Specific tools are also available to users to process strong-motion data and select ground-motion suites for codebased seismic structural analyses.

The strong influence of lateral heterogeneities and of source properties on the spatial distribution of ground motion indicates that the traditional methods require an alternative when earthquake records are not available. The computation of broadband synthetic seismograms makes it possible, as required by a realistic modelling, to take source and propagation effects into account, fully utilizing the large amount of geological, geophysical and geotechnical data, already available. For recent earthquakes, where strong motion observations are available, it is possible to validate the modelling by comparing the synthetic seismograms with the experimental records. The realistic modelling of the seismic input has been applied to a first-order seismic zoning of the whole territory of several countries. Even though it falls in the domain of the deterministic approaches, the method is suitable to be used in new integrated procedures which combine probabilistic and deterministic approaches and allow us to minimize the present drawbacks which characterise them when they are considered separately. Detailed modelling of the ground motion for realistic heterogeneous media (up to 10 Hz) can be immediately used in the design of new seismo-resistant constructions and in the reinforcement of existing buildings, without having to wait for a strong earthquake to occur. The discrepancies between the ground responses computed with standard methods and the results of our detailed modelling cannot be ignored when formulating building codes and retrofitting the built environment.

Near fault ground motions may contain impulse behavior on velocity records. Such signals have a particular indicator which makes it possible to distinguish them from non-impulsive signals. These signals have significant effects on structures; therefore, they have been investigated for more than 20 years. In this study, we used Ricker and Morlet wavelets in order to analyze the wavelet power spectrum of the strong motion signals to investigate the impulsiveness. Both the area around the PGV and the area that exceeds the minimum threshold for the energy function are used in order to determine the position of the pulse. On both of these cases, particular criteria are used in order to characterize the signal. Then, we calculate the pulse period of the pulse region. Ricker and Morlet wavelets are also used to mimic the pulse signal. This method provides advanced information about the position of the maximum energy of the pulse part of the signal. We found that the impulsive part of the signal is frequently at the position where PGV occurs and the Ricker wavelet is better than the Morlet wavelet on mimicking the pulse part of the waveform. Spectral responses of