Attenuation Law and Local Hazard Evaluation

The paper refers to the attenuation of macroseisrnic intensity with epicentral distance. A new attenuation law is discussed, with particular reference to Italian conditions. For earthquakes of many Italian seismic regions, the new formula shows a much better fitting compared to traditional attenuation laws. The probabilistic approach to the evaluation of local hazard is then discussed under the Poissonian hypothesis for the occurrence process, with particular attention to the computational errors due to the (possible) non homogeneous spatial distribution of epicenters. A simple way to reduce such errors is suggested. Finally, the case in which the occurrence process does not comply with the Poissonian hypothesis is briefly discussed.