GEOSCAN, résultats de la recherche


TitreStation magnitude corrections ad related issues for eastern Canada
AuteurBent, A L
SourceCommission géologique du Canada, Dossier public 6505, 2010, 36 pages,
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
ProvinceTerre-Neuve-et-Labrador; Nouvelle-Écosse; Nouveau-Brunswick; Île-du-Prince-Édouard; Québec; Ontario; Manitoba; Nunavut
SNRC1; 2; 11; 12; 13; 14; 21; 22; 23; 24; 25; 26; 27; 30; 31; 32; 33; 34; 35; 36; 37; 40; 41; 42; 43; 44; 45; 46; 47; 52; 53; 54; 55; 56; 62A; 65; 66; 75; 76; 86; 87
Lat/Long OENS-116.0000 -50.0000 71.0000 40.0000
Sujetssecousses séismiques; magnitudes des séismes; études séismiques; risque de tremblement de terre; foyers des séismes; sismographes; séismologie; réseau sismique; géophysique
Illustrationstables; plots
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
ProgrammeService d'information sur les dangers naturels au Canada, Service d'information sur les dangers naturels au Canada
Diffusé2010 05 20
Résumé(disponible en anglais seulement)
Earthquake magnitudes are generally defined as an average (most often, the arithmetic mean) of magnitudes calculated at many individual seismograph stations. While some variation in station magnitudes stems directly from the seismic source (for example, radiation pattern or directivity) conditions beneath the recording station also affect the calculated value. For example, soft soils tend to amplify the seismic signal resulting in an apparent magnitude that is higher than the true value. By analyzing the differences between the magnitude determined at a specific station and the average magnitude for a large number of earthquakes, a site correction for the station can be determined. The intent of this study is to determine the station corrections for those seismographs routinely used in the calculations of magnitudes in eastern Canada. Corrections are determined for both the mN and ML magnitude scales. Additionally the magnitude residuals were further evaluated to determine whether they were dependent on parameters such as distance, azimuth or frequency. The effects of azimuth and frequency appear to be minimal. There does appear to be a distance dependency suggesting that the attenuation relation used in the magnitude calculation may need to be modified. Finally, several issues relating to magnitudes are raised, the resolution of which are beyond the intended scope of this paper.