HR: 0800h
AN: S51B-04    [Abstracts]
TI: Spatio-temporal evolution of triggered seismicity at Nova Ponte Reservoir, Brazil
AU: * Chimpliganond, C
EM: naibert@unb.br
AF: Observatório Sismológico, Campus Universitário Darcy Ribeiro, SG-13, Universidade de Brasília, Asa Norte, Brasilia, DF 70910-900, Brazil
AU: Sousa, K T
EM: kate@unb.br
AF: Observatório Sismológico, Campus Universitário Darcy Ribeiro, SG-13, Universidade de Brasília, Asa Norte, Brasilia, DF 70910-900, Brazil
AU: Caixeta, D d
EM: daniel@unb.br
AF: Observatório Sismológico, Campus Universitário Darcy Ribeiro, SG-13, Universidade de Brasília, Asa Norte, Brasilia, DF 70910-900, Brazil
AU: Barros, L V
EM: lucas@unb.br
AF: Observatório Sismológico, Campus Universitário Darcy Ribeiro, SG-13, Universidade de Brasília, Asa Norte, Brasilia, DF 70910-900, Brazil
AU: França, G S
EM: georgesand@unb.br
AF: Observatório Sismológico, Campus Universitário Darcy Ribeiro, SG-13, Universidade de Brasília, Asa Norte, Brasilia, DF 70910-900, Brazil
AB: Nova Ponte Reservoir is located at Minas Gerais State, SE of Brazil, on the Araguari river. The lake is situated at the boundary between two geotectonic provinces: the Neoproterozoic Brasilia Mobile Belt and a Phanerozoic volcano-sedimentary basin so called Parana Basin. The impoundment started in October 1993 creating a lake with volume of 12.8 km³ and maximum depth of 132 m. The pre-impoundment monitoring was made with one station for eigth years, and no local event had been detected. Two months after the lake start to be filling, the occurrence of some events felt by the local population lead to the deployment of a five vertical analog stations network. In 1995 this network was replaced by a digital one, which is operating until now. The almost continuous monitoring shows that the seismic activiy at Nova Ponte Reservoir is a proved case of reservoir triggered seismicity. Initially the events occured 25 km south of the dam, in a cluster named Area 1, with maximum magnitude of 2.0 m_D. Soon after the activity at this area decreased and a continuous seismicity appeared at another area, named Area 2, with more widespread epicentral distribution. Most of the triggered events occurs at this area. A conspicuous cluster of epicenters is located 10 km south of the dam, where the two largest events were detected, on April 1995 with 3.5 m_D, and on May 1998 with 4.0 m_b and VI MM maximum intensity (Assumpção et al., 2002 PAGEOPH). The last one corespond to the second largest triggered earthquake in Brazil. The seismicity at these two areas was well studied. Since July 2004 some events have been located in a small area half distance between areas 1 and 2, named Area 3. Compared to areas 1 and 2, this area show less number of events, with maximum magnitude of 2.1 m_D. More recent data analysis shows another new cluster of events situated around 35 km east of the dam where occurred on July 23, 2006 an event of 2.9 m_D. In this study we present preliminary results for this activity that will be investigated as a probably result of spatio-temporal evolution of reservoir-triggered seismicity.
DE: 7200 SEISMOLOGY
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Joint Assembly