HR: 16:55h
AN: U54B-03    [Abstracts]
TI: Characteristics of Andean earthquakes felt at long distances in Brazil
AU: * França, G S
EM: georgesand@unb.br
AF: Observatório Sismológico - IG/UnB, SG 13 Campus Universitário Darcy Ribeiro - Asa Norte, Brasília, DF 70910-900, Brazil
AU: Assumpção, M
EM: marcelo@iag.usp.br
AF: Instituto de Astronomia, Geofíisica e Ciências Atmosféricas - USP, Rua do Matão 1226 Cidade Universitária, São Paulo, SP 05508-090, Brazil
AU: Santiago, P S
EM: pablo.sisan@gmail.com
AF: Observatório Sismológico - IG/UnB, SG 13 Campus Universitário Darcy Ribeiro - Asa Norte, Brasília, DF 70910-900, Brazil
AB: In the past several decades, more than 40 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 in population and skyscrapers in large cities, such long-distance effects are becoming more frequent. In São Paulo, for example, such macroseismic effects have been observed every 3-5 years on average. We present a study of the characteristics of the earthquakes and cities more susceptible to cause high-rise buildings to oscillate. Most earthquakes occur at intermediate or large depths, such as in the Jujuy and Santiago del Estero regions of northern Argentina. Magnitudes as low as 5.0 mb have caused long distance macroseismic effects. Most affected cities lie in sedimentary basins, such as São 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. An analysis of the ground motion amplitudes, as recorded by nearby broadband stations, will be presented.
DE: 7200 SEISMOLOGY
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7299 General or miscellaneous
SC: Union [U]
MN: 2007 Joint Assembly