Seismicity of North‐East Italy demarcates the boundary between the Adria microplate and the Eurasian plate. The actual state of stress is a consequence of the Adria microplates progressive motion and its anti‐clockwise rotation with respect to the Eurasian plate. The seismotectonic characteristics of the region are not homogeneous, and the contemporary seismic deformation pattern is quite complex, being the results of the superimposition of several distinct strain fields related to different Alpine phases. The last severe earthquake was the 1976 Ms=6.5 Friuli earthquake, which caused lot of damage and hundreds of casualties. In 1977, after this destructive earthquake an integrated seismic network was installed to monitor the regional seismicity of NE Italy and surroundings as well as to provide high quality data for research projects in regional and global broadband seismology.

Since the last years, in the framework of a project supported by the Italian Civil Defence Agency, the routine activity of the OGS seismic monitoring has been enriched with the real time estimate of seismic moment tensor and ShakeMap computation. In the framework of validation of the procedures that we apply for real time estimates, we chose as test cases the 2008 Iwate‐Miyagi Nairiku (Mw=6.9) earthquake and one aftershock of Mw=5.5. During the talk I will present some preliminary results about the validation analysis on Japanese earthquakes and I revise some strong earthquakes occurred in NE Italy and surroundings.

The formulation of design elastic displacement spectra for seismic codes, and zoning studies of seismic hazard for long-period structures are becoming of crucial importance in modern earthquake engineering. The growing diffusion of displacement-based design approaches together with the availability of good quality digital strong motion data has allowed to obtain reliable spectral shapes for seismic design up to 10 s. However additional studies have still to be accomplished especially in deep sedimentary basins and plains to investigate site amplification effects during large levels of shaking and to infer the resulting displacement response spectra shape (DRS). Large amplitude long-period waves from distant large earthquakes can provide enough energy to excite the deep sedimentary basin structure. Existing accelerometric seismic networks are normally deployed on rock soil type and data recorded within deep basins (having a good seismic site characterization) from large earthquakes are difficult to find in the international databases. Here we focus on the numerical modeling of 3-D wave-field in 1D flat layered and 3D structures in the Po and Venetian plains (Italy). Modeling is needed because of the lack of recordings of mediumstrong earthquakes within deep soft sediments. We investigate earthquakes with magnitudes larger than M = 6.5 and hypocentral distances greater than 50 km. The main results are represented by: 1) the estimation of expected DRS in the period range from 1 to 10 s in the Po and Venetian plains, 2) the comparison between the DRS resulting from different numerical simulations (flat layered and 3D structures) and the uniform hazard DRS available for Italy and, 3) the evaluation of the influence of deep sediments in DRS shape to eventually implement this effect in seismic codes. Moreover 1D and 3D simulated DRS are compared with DRS obtained from recordings in the Kanto basin where similar long period displacement is observed.