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TitleDuration Magnitudes For Nahanni Earthquakes Recorded By Field Networks, October 1985, January 1986, September 1986
AuthorWetmiller, R J; Plouffe, M
SourceGeological Survey of Canada, Open File 1512, 1987, 42 pages, (Open Access)
Documentopen file
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS95F/01; 95F/02; 95F/07; 95F/08; 95F/09; 95F/10; 95F/15; 95F/16; 95K/01; 95K/02; 95K/07; 95K/08; 95K/09; 95K/10; 95K/15; 95K/16; 95N/01; 95N/02; 95N/07; 95N/08; 95N/09; 95N/10; 95N/15; 95N/16
AreaNahanni River
Lat/Long WENS-125.0000 -124.0000 64.0000 61.0000
Subjectsgeophysics; mathematical and computational geology; earthquakes; aftershocks; computer applications; software
Geological Survey of Canada (Atlantic)
Natural Resources Canada Library - Ottawa (Earth Sciences)
Natural Resources Canada library - Vancouver (Earth Sciences)
Natural Resources Canada library - Calgary (Earth Sciences)
Released1987 07 01; 2018 07 03
AbstractSince the two large earthquakes in the Nahanni area, in October and December 1985, three field surveys have been conducted. In the last one, in September 1986, nearly 200 aftershocks were located. Using the permanent Fort Simpson station, magnitudes of only 26 larger events could be determined. Magnitudes of 309 smaller events were calculated using their signal duration on the analog field stations. Two programs, discussed here, were used in this calculation. One organizes the calibration events. The other one, with an inverse matrix calculation, finds a best-fit magnitude duration equation. For the third Nahanni survey, an equation:
MC= -0.42 + 1.72*log(CL) + 0.01*D
where CL is the coda-length and D the hypocentral distance of the events, is proposed to define the relationship between signal
duration and magnitude. The same type of equation was used to find duration magnitudes for the two other surveys. Magnitudes were assigned to 347 events from the October 1985 survey and 239 events from the January 1986 survey. The magnitudes determined will be used to calculate the magnitude-frequency properties of the aftershock activity.