The construction of the Tucuruí dam in the decade of 80, situated in the River Tocantins, interrupted the navigation in this stretch of the watercourse. To give continuity to the passage of the fluvial transports the Eletronorte and Camargo Corrêa S.A., initiated the construction of two canals in the neighborhoods of the city of Tucuruí/PA. Floodgate 1 is connected to the axis of the dam, and Floodgate 2 will be situated near the city of Tucuruí, in the left edge of the Tocantins River. The dismounting of the rocks caused discomfort to the population which complained about damages in the residences. In this way, the Seismological Observatory of the University of Brasília monitored the vibrations generated by blasting, with the aim to make a diagnosis and see if there is a relation between the detonations and the residences cracks. The velocity records of the particle vibration were obtained by engineering seismometer installed near the damaged residences. Records of 27 distinct points were analysed, and these information were intercorrelated with geological, pedological and geotechnical data, to understand its effects and to obtain the equation of seismic attenuation for this region. The 42 values of the particles velocity obtained were below the recommended value of 15 mm/s defined by the Brazilian norms as the upper level to avoid damages to the nearby residences. Regarding the sound pressure only one single measured value was beyond the intensity established by the Brazilian norms.
removal of rock; seismograph monitoring; vibration; equation of attenuation
