The degree of damage due to a strong earthquake is often described by the macroseismic intensity, which is determined after the evaluation of the macroseismic questionnaires. Since a more objective measure of ground shaking is preferred by scientists (seismologists, engineers, urban planners, etc.), accelerographs are manufactured to provide an instrumental measure of the ground shaking at a specific site. Thus, by using strong motion records, scientists want to understand the effect of the source-to-site path, as well as the one of the local geological conditions on the formation of the shaking. The macroseismic and the accelerographic data are used to improve the earthquake resistant codes and to design earthquake hazard maps.