Seismicity around Brazilian dam reservoirs
- Univ. of Western Ontario, London (Canada)
More than 30 cases of seismicity associated with dam reservoir sites are known throughout the world. Despite the lack of data in some areas, where seismicity occurred after reservoir impounding, there have been distinct seismic patterns observed in seismic areas after dam projects implantation. This has demonstrated that reservoir loading can trigger earthquakes. A mechanism of earthquake generation by reservoir impounding is proposed here with particular application to the Brazilian cases and to areas subject to low confining stress conditions in stable regions. Six artificial lakes are described and the associated earthquake sources are discussed in terms of natural or induced seismicity. Earthquake monitoring in Brazil up to 1967, when Brasilia's seismological station started operation, was mainly based in personal communications to the media. Therefore, there is a general lack of seismic records in relatively uninhabited areas, making it difficult to establish a seismic risk classification for the territory and to distinguish natural from induced seismicity. Despite this, cases reported here have shown an alteration of the original seismic stability in dam sites after reservoir loading, as observed by the inhabitants or records from Brasilia's seismological station. All cases appear to be related to an increase in pore pressure in permeable rocks or fracture zones which are confined between impermeable rock slabs or more competent rock. It is apparent that some cases show some participation of high residual stress conditions in the area.
- OSTI ID:
- 5964833
- Journal Information:
- Environmental Geology and Water Sciences; (United States), Vol. 10:3; ISSN 0177-5146
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
BRAZIL
DAMS
WATER RESERVOIRS
SOIL-STRUCTURE INTERACTIONS
SEISMIC EFFECTS
SEISMICITY
EARTHQUAKES
PORE PRESSURE
SEISMIC EVENTS
STRESS ANALYSIS
DEVELOPING COUNTRIES
LATIN AMERICA
SOUTH AMERICA
SURFACE WATERS
130200* - Hydro Energy- Site Geology & Meteorology
580000 - Geosciences