Effects of local site and building parameters on damage distribution in Angra do Heroísmo—Azores

During the M_w=6.9 January 1, 1980 earthquake in the Azores, the damage distribution in the town of Angra do Heroísmo, in Terceira Island, had a non-homogeneous spatial character. In order to understand the observed pattern of damage a microtremor survey was carried out, using ambient vibrations, and the data were analysed with the J-Sesame software, following the H/V Nakamura methodology. The results are in good agreement with the surface geology and they show a good correlation with the observed damages. Two building surveys were performed, in 1980 on damage evaluation and in 2000 on characterization of few building parameters. With all these elements (surface geology type, soil peak frequency, building type, number of stories and damage level) for 2111 buildings it was possible to perform several interparameter analysis, which enabled the identification of indicators that could be used to improve the damage estimation for future events.