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TitreSeismic evaluation of a multipurpose tower in Yellowknife, Northwest Territories, Canada
AuteurEdwards, W N; Asudeh, I; Andews, C; Jensen, G; Murphy, F; Ashlie, R
SourceSeismological Research Letters vol. 83, no. 5, 2012 p. 787-797,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110384
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceTerritoires du Nord-Ouest
Lat/Long OENS-115.0000 -114.5000 62.5000 62.2500
Sujetsinterpretations sismiques; sismicité; données sismiques; séismologie; réseau sismique; géophysique
Illustrationslocation maps; histograms; rose diagrams; plots; tables
ProgrammeService d'information sur les dangers naturels au Canada, Service d'information sur les dangers naturels au Canada
Résumé(disponible en anglais seulement)
In 2011, decisions were made to significantly upgrade the Yellowknife seismic array in the Northwest Territory, Canada to modern standards. Part of this upgrade required the installation, at each element of the array, of a 7.62m free-standing aluminum frame tower to provide a platform for solar panels and radio communications antenna. To ensure current seismic background levels at the array would not be adversely affected by vibrations of this tower under wind loading, an experiment was devised to measure the seismic characteristics of the tower on site under actual wind conditions between February 21 and April 4, 2011. Spectral analysis shows that the tower has a fundamental vibrational mode at 2.0 Hz, which decays approximately as R-3, along with a twisting mode and several higher order harmonics within the passband of the short period sensors. Measurement of the modal growth rates as a function of wind speed allows construction of a simple model to determine the minimum safe separation distance between the seismic vault and tower. Based on these findings a separation of between 30 - 40 m is recommended to avoid background contamination with tower-generated noise during the majority of wind conditions likely to be experienced by the array.