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Some 350,000 gravity observations have been compiled, edited and contoured by an automated computer procedure to produce a two colour edition of the Bouguer Anomaly Map of Canada. The intervals between gravity stations varied from a few hundred meters to a few tens of kilometers. From these stations averages were calculated for equal area blocks of size ii km squares (corresponding to 0.1° along the meridian). After editing, the resulting 74,091 points were subdivided into 17 subareas to accommodate memory size restriction imposed by the contouring program, and then grid points at 15 km interval were calculated. The final map was produced in a single sheet from this data set at a scale of 1:5,000,000. To aid production and avoid errors guides for each of the colour band separation peel coats were also prepared by computer.Quelque 350 000 observations gravimetriques ont ete compilees, editees et mises en isogammes par un trace informatise afin de produire une edition en deux couleurs de la carte des anomalies de Bouguer au Canada. Les intervalles entre les stations gravimetriques variaient entre quelques centaines de metres a quelques dizaines de kilometres. A partir de ces stations, on calcula des moyennes pour des blocs de zones egaux 11 km carres (correspondant a 0,1 ° le long du meridien). Apres l'edition, les 74091 points resultant ont ete subdivises en 17 sous-zones afin de respecter la limite de taille de la memoire imposee par le programme de tracage en courbes, et on a ensuite calcule des points de quadrillage situes a des intervalles de 15 km. La carte finale a ete produite sur une seule feuille a partir de ces donnees a une echelle de 1/5 000 000. Afin d'aider a la production et d'eviter des erreurs, on a egalement prepare, a l'aide de l'ordinateur, des guides pour chacune des couches pelliculables de selection des bandes de couleurs.

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Earthquake data are utilized in conjunction with bathymetry and gravity measurements to study the seismotectonics of the Beaufort Sea area. The epicentre cluster in the Beaufort Sea is confined to the continental slope between the 200 and 2400 m bathymetry contours and falls between the seaward −20 mGal and the landward + 40 mGal contours of an elliptically shaped free-air gravity anomaly. The cluster, which experiences an average of one earthquake magnitude ≥ 4 per year, is shown by epicentre relocation studies to be a distinct zone and not the result of mislocations of earthquakes originating from a spatially confined source. Theoretical calculations of the stress field under the region where the gravity anomaly is most pronounced show that the horizontal component of the stress field is deviatoric tension normal to the axis of the continental margin; focal parameters of the June 14, 1975, mb 5.1, Ms 4.2 Beaufort Sea earthquake indicate deviatoric tension in the same (east–west) direction at a depth of 40 km. The relatively small surface waves from this and other Beaufort Sea earthquakes, compared to other on-shore Arctic earthquakes, are probably due to this deeper focus at the continental margin. The horizontal component of the deviatoric compression of this earthquake is north–south; a horizontal compressive stress from the north may be transmitted through the Arctic Ocean lithosphere from the Nansen–Gakkel spreading ridge. It is suggested that these stresses are acting on localized zones of weakness.
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