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TitleReservoir-triggered seismicity at the Toulnustouc hydroelectric project, Québec North Shore, Canada
AuthorLamontagne, M; Hammamji, Y; Peci, V
SourceBulletin of the Seismological Society of America vol. 98, no. 5, 2008 p. 2543-2552, https://doi.org/10.1785/0120070240
Year2008
Alt SeriesEarth Sciences Sector, Contribution Series 20070279
Documentserial
Lang.English
Mediapaper; on-line; digital
File formathtml; pdf (Adobe® Reader®)
ProvinceQuebec
NTS22F; 22G; 22J; 22K; 22N; 22O
AreaToulnustouc Reservoir; Lac Sainte-Anne
Lat/Long WENS-70.0000 -66.0000 52.0000 49.0000
Subjectsgeophysics; structural geology; tectonics; seismology; seismicity; earthquakes; water loading; reservoirs; dams; hydroelectric power; seismological network; seismographs; crustal studies; crustal movements; stress analyses; deformation; bedrock geology; structural features; fractures; fracture zones; lineaments; faults; faults, slip; pore pressures; tectonic setting; tectonic interpretations; Canadian Shield; Canada National Seismograph Network (CNSN); Lower St. Lawrence Seismic Zone; anthropomorphic causes; elastic stress; Precambrian
Illustrationssketch maps; tables; satellite images; seismograms
ProgramReducing Risk from Natural Hazards
LinksEarthquakes Canada - Séismes Canada
AbstractHydro-Québec's Toulnustouc hydroelectric complex is located approximately 120 km north of Baie-Comeau on the Québec North Shore region. The project involved the construction of a 77-m-high dam and a 45-m-high dike that allowed the expansion of an existing 235 km2 reservoir by some 22 km2.When completely filled, the new part of the reservoir has a maximum depth of 75 m. Starting on 10 February
2005 and over a period of four days, the water of the original reservoir was used to start filling the new part. The water level of the entire reservoir increased by another 10 m after the spring snowmelt. The project also included a 9.8-km-long headrace tunnel constructed in Precambrian bedrock that creates a 170-m water head between the reservoir and the powerhouse. Electricity production started in May 2005. The complex is located in an area of low-level earthquake activity on the Canadian Shield. Four stations of the Canada National Seismograph Network (CNSN) located within 100 km of the reservoir provide a location threshold with a magnitude of about 1.2 (mN). To complement the CNSN, two portable seismographs were installed near the flooded area and the headrace tunnel about one week before flooding started. Between February and mid-May 2005, a total of four triggered earthquakes were recorded by the field instruments and the CNSN stations. The first event, a magnitude 1.4 (mN), occurred 16 days after flooding of the extension of the reservoir started. Three events were located beneath the reservoir and one was near the tunnel between the reservoir and the powerhouse where the water pressure is most intense. Numerous smaller but unlocatable events (mN < 1:0) were detected by one of the field stations. About two years later, two events separated by one minute and recognized as multiplets occurred near the reservoir. The small stress perturbations that led to the reservoir-triggered seismicity at Toulnustouc support the hypothesis that the mid to upper crust of intraplate areas is in a state of stress close to failure.
GEOSCAN ID224302