IAG-IASPEI 2017

講演情報

Oral

IASPEI Symposia » S02. Anthropogenic seismicity

[S02-2] World overview of anthropogenic seismicity II

2017年7月31日(月) 10:30 〜 12:00 Room 403 (Kobe International Conference Center 4F, Room 403)

Chairs: Carlos Alberto Vargas Jimenez (Universidad Nacional de Colombia) , William L. Ellsworth (Stanford University)

10:30 〜 10:45

[S02-2-01] Reservoir-Triggered Seismicity in Brazil: characteristics and new cases

Lucas Barros1, Marcelo Assumpcao2, Juraci Carvalho1, Luiz Ribotta3 (1.University of Brasilia, Brasilia, Brazil, 2.University of Sao Paulo - Sao Paulo -SP - Brazil, 3.The Institute of Technological Research of the SP State, Sao Paulo, Brazil)

We report here 26 cases of reservoir-triggered seismicity (RTS) in Brazil, emphasizing the cases observed in the last ten years. In worldwide terms Brazil presents a relatively high number of RTS. Nevertheless, if we consider the Brazilian high number of reservoirs with power to produce RTS this number is not so expressive. Not differently of the rest of the world, in Brazil the interest for the RTS subject began around the 70s when the first case had been identified (3.7 mb and V-VI(MM).
Studies on RTS in Brazil have been made there about 40 years ago, by the universities of Brasilia, Sao Paulo, Rio Grande do Norte and the Technological Research Institute of the State of Sao Paulo in partnership mainly with the national energy companies. In the middle of the 70´s initiated the reservoir seismographic monitoring and nowadays almost all the largest Brazilian reservoirs have seismic stations installed around them.
Two magnitudes 4 RTS earthquakes were observed, the biggest 4.2mb intensity (MM) VI-VII. About 80 percent of the RTS cases present initial seismicity, and the rest with delayed response with some cases having more than one main event. In Brazil, many cases of RTS exhibit a series of common characteristics. Furthermore, the magnitude of triggered event is not directly proportional to the depth of the water column or on the total volume of the reservoir, although, the triggered seismic activity has been more common in reservoirs with depth > 100 m (about a half of these reservoirs presented RTS). However, there are reservoirs that are higher than 100 meters that never had presented RTS and others with height less than 50 m with expressive triggered seismicity. Therefore, there is not a direct relationship between the maximum magnitude of a triggered earthquake and the dam height and the volume of the reservoir.
In this work, we will present the Brazilian RTS cases and discuss its features, highlighting the new cases, including that one´s not yet reported.