HR: 1340h
AN: S23B-0232    [Abstracts]
TI: Induced Seismicity at the Toulnustouc Hydroelectric Project, Quebec North Shore, Canada
AU: * Lamontagne, M
EM: malamont@nrcan.gc.ca
AF: Natural Resources Canada, 588 Booth Street/ Rm. 338, Ottawa, ON K1A 0Y7 Canada
AU: Hammamji, Y
EM: hammamji.yousef@hydro.qc.ca
AF: Hydro-Quebec, 855 Ste-Catherine Est, 12e ‚tage, Montreal, Qc H2L 4P5 Canada
AU: Debel, M
EM: debel.marianne@hydro.qc.ca
AF: Hydro-Qu‚bec, Projet de la Toulnustouc, C.P. 4000, Baie-Comeau, Qc G4Z 3B6 Canada
AB: Hydro-Quebec's Toulnustouc hydroelectric complex is located approximately 100 km north of Baie-Comeau on the Quebec North Shore. The project involved the construction of a 77 m high dam and a 45 m high dike that allowed the expansion of an existing reservoir by some 22 km2. The extension to the reservoir has a maximum depth of 75 m. The project also included the flooding of a 9,8 km long headrace tunnel, creating a 170 m water head between the top of the reservoir and the powerhouse. The flooding of the new part of the reservoir started on February 10 and finished about four days later, reducing the water level of the old part of the reservoir in order to fill the new part. About 10 meters were added after the snowmelt. 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 of about magnitude mN 1.2. To complement the CNSN, two portable seismographs were installed near the flooded area and the headrace tunnel one week before flooding started. Between February and mid-May 2005, a total of four induced earthquakes have been recorded by the field instruments and the CNSN stations. The largest event, a magnitude 1.4 (mN), occurred sixteen days after flooding of the extension of the reservoir started. Three events were located beneath the reservoir and one was near the headrace tunnel where the water pressure is most intense. Numerous smaller but unlocateable events (mN < 1.0) were detected by one of the field stations. Since May, no event has been recorded, suggesting that the activity is back to its pre-impoundment level. Since the new portion of the reservoir filled very rapidly, it was used as an analogue to a flooding event to test remote sensing usage in catastrophic events. Satellite imagery was acquired to test the change detection capability and is currently being analyzed.
UR: http://www.hydroquebec.com/toulnustouc/
DE: 7205 Continental crust (1219)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: Fall Meeting 2005