HR: 0800h
AN: T31A-0276    [Abstracts]
TI: Andean earthquakes felt at long distances in Brazil! What will we do?
AU: * Franca, G S
EM: georgesand@unb.br
AF: Observatorio Sismologico - Universidade de BrasÃÆ'Į'ÃÆ'‚­lia, SG 13 Campus Universitario Darcy Ribeiro, Brasilia, DF 70900-910, Brazil
AU: Assumpcao, M
EM: marcelo@iag.usp.br
AF: Instituto de Astronomia, Geofisica e Ciencias Atmosfericas - Universidade de Sao Paulo, Rua do Matao 1226 Cidade Universitaria, Sao Paulo, SP 05508-090, Brazil
AU: Santiago, P S
EM: pablo.sisan@gmail.com
AF: Observatorio Sismologico - Universidade de BrasÃÆ'Į'ÃÆ'‚­lia, SG 13 Campus Universitario Darcy Ribeiro, Brasilia, DF 70900-910, Brazil
AB: In the past several decades, more than 45 Andean earthquakes have been felt in Brazilian cities, thousands of kilometers away from the epicenter, especially by oscillations of high-rise buildings. Because of the increase of skyscrapers in big cities, such long-distance effects are becoming more frequent. In Sao Paulo, for example, such macroseismic effects have been observed every 3-5 years on average. We present a study on the characteristics of the earthquakes and cities more susceptible to cause high-rise buildings to oscillate. Most earthquakes occur at intermediate or large depths and those with magnitudes larger or equal than 5.0 mb, such as in the Jujuy and Santiago del Estero regions of northern Argentina, have caused long distance macroseismic effects. Most affected cities lie in sedimentary basins, such as Sao Paulo and Manaus, which can amplify the ground motions through basin resonance. In some cases, buildings with the longest axis oriented perpendicular to the largest S amplitudes (SH component) seem to be more susceptible to oscillations. As response levels are small, we used a on broad-band stations on each floor of a residential building (9-storey) in Brasilia City, in order to identify the characteristics of the building for preliminary analysis. This result is being compared with analysis of the ground motion amplitudes, recorded by nearby broadband stations.
DE: 7200 SEISMOLOGY
DE: 7209 Earthquake dynamics (1242)
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7299 General or miscellaneous
SC: Tectonophysics [T]
MN: 2007 Fall Meeting