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The aim of our work is to research the most probable distribution of the energy of aftershocks. We started by applying one of the fundamental principles of statistical mechanics that, in the case of aftershock sequences, could be expressed as: the greater the number of different ways in which the energy of aftershocks can be arranged among the energy cells in phase space the more probable the distribution. We assume that each cell in phase space has the same possibility to be occupied, and that more than one cell in phase space can have the same energy. Seeing that seismic energy is proportional to products of different parameters, a number of different combinations of parameters can produce different energies (e.g. different combinations of stress drop and fault area can release the same seismic energy). Let us assume that there are g_i cells in the aftershock phase space characterised by the same energy released eps_i. Therefore we can assume that the Maxwell-Boltzmann statistics can be applied to aftershock sequences with the proviso that the judgement on the validity of this hypothesis is in agreement with the data. The aftershock energy distribution can therefore be written as follow: n(eps)=Ag(e)exp(-eps*beta) (1) (**) where n(eps) is the number of aftershocks with energy; eps, A and beta are constants. (**) Equation (1) is a well known distribution function of statistical mechanics. Throughout this presentation, for the sake of brevity we refer to it as "The Maxwell-Boltzmann model". Actually we should have said "the statistical mechanics distribution function that was adopted in the Maxwell-Boltzmann formulation".

Theoretical formulations of inhomogeneous waves in low-loss media have been suggested by a number of researchers due to the important role played by anelasticity in changing the characteristics of seismic waves. The Homogeneous Isotropic Linear Viscoelastic Model (HILV) introduced by Borcherdt (2009) is particularly promising because of its mathematical simplicity and the handiness to test the model in real seismograms. We showed that the seismograms of the explosion, in 2007, of a 2nd World War bomb found in Milan recorded by a seismic station at 2 Km epicentral distance, exhibit a clear elliptical prograde P wave particle motion (Marcellini and Tento, 2011) as predicted by HILV. We observed a similar P wave prograde elliptical motion analysing a ML 4.8 earthquake that occurred on July 17, 2011 in the Po Valley at a 48 km epicentral distance from a seismic station located at Palazzo Te, Mantova (Daminelli et al., 2013). In both cases the stations were situated on deep quaternary sediments of the Po Valley. Based on the measured Vp and Vs and the amplitude of the recorded motion, the strain at the station sites was estimated to be 10e-6 - 10e-7. In this paper we extended the analysis of the previously mentioned seismograms to check the feasibility of the HILV application to other types of waves that are particularly relevant in fields such as engineering seismology. We focus on the S waves (as it is well known that HILV predicts the split of S in S type I and S type II ) of the seismograms of the earthquake recorded in Mantova. The results show that observational evidences of HILV are not as clear as for P waves, probably because of noise or superposition of converted waves. However, once the validity of HILV by P waves is established, the whole seismogram can be interpreted following HILV, confirming the relevancy of anelasticity also at low strain.

A masonry belfry was the object of an experimental survey of the duration of days. The belfry was equipped with velocimeters located at different points inside the structure. The elaboration of the data collected under ambient vibration enabled to establish a correlation between the estimated modal properties and the temperature; such a correlation is acknowledged in the literature, but it is not very often characterized. After a brief description of the case study, the main results are reported and discussed.

The Santuario della Rocca, whose construction began in the XI century, is situated on the top of a calcareous hill in the centre of the village of Sabbio Chiese (Provincia of Brescia). During the November 24, 2004 Garda Lake earthquake (M=5.2) the church, situated at 9.5 Km epicentral distance, was severely damaged. A detailed microtremor survey was conducted in the church and immediately outside the church. In addition with a seismic profile along the hillside we investigated the influence of the topography on the damage level. The 5 stations installed at different elevation on the hillside showed an amplification (in the range of 4-9 Hz) that increases according to the altitude. The Santuario della Rocca layout has the longitudinal dimension more than two times the lateral dimension: the mean fundamental period (the mean of fundamental periods computed by the stations inside the church) is 2,16 Hz along the minor axes and 3 Hz along the major axes. Moreover we found that the evaluated fundamental period of the Santuario della Rocca structure was significantly dependent on the positions of the seismic stations inside the church. As confirmed by H/V analysis these results were due to the uneven soil foundation properties, with strong variations in few meters distance. The damage pattern has been found in good correlation with our results.

Particle motion of body waves allows to differentiate between dissipative and non dissipative soil type. Particularly relevant is to establish the strain threshold between elastic and non elastic soil behavior and, in case of the presence of anelasticity, to check the reliability of simple models. In the present paper we analyse the records of two superficial open quarry explosions of unexploded 2nd world war bombs dropped by Allies air raid, recently rescued at a few meters depth close to Milano Central station. The seismic stations located at 2.5 km and 550 m epicentral distance, respectively, show a clear separation between body waves and surface waves. The results show: 1) despite the low strain (max strain not exceeding 10-7) elastic approx is not applicable; 2) the data evidence a clear elliptical prograde P wave particle motion with g greater than 0 and less than 30 degrees (g is angle between the P propagation and the A attenuation vector, P precedes A); 3) the Homogeneous Isotropic Linear Viscoelastic model is sufficient to describe conveniently this inhomogeneous P wave motion.

We describe a proposal of seismic microzonation regulations for the Emilia-Romagna Region to be eventually adopted as a regional code for land use planning. These regulations supply the reference input motion for each municipality and define three levels of analysis to be selected on the base of the seismicity level and the economical relevancy of the area under investigation. The prescribed microzonation studies are organized into three levels. The first level, which could be thought of as preliminary zonation, is based on the available geological and geotechnical information and does not require further additional field investigations. The second level mainly focuses on the seismic site amplification assessment and requires additional geotechnical and geophysical investigations. This level supplies tables which relates ground motion amplification to average Vs and bedrock depth of the site. Site effects are expressed in terms of expected PGA and Housner Intensity; the latter is computed by assuming two intervals of integration. The third level is recommended in cases where instability phenomena cannot be excluded or major or strategic buildings and lifelines must be located.