1985 Nahanni earthquakes

Earthquakes in the Northwest Territories, Canada February 2025 1985 Nahanni earthquakes Canada Northwest Territories#Canada 1985-12-23 05:16:05 509142 iscgem509142 1985 12 22 22:16:05 6.9 w y 6.0 km on 62.222 -124.239 region:CA_type:event inline,title Thrust Canada 6M 6.9 – Northwest Territories, Canada https://earthquake.usgs.gov/earthquakes/eventpage/iscgem509142/executive United States Geological Survey 6 March 2022 2.37 gHeidebrecht Arthur Engineering implications of the 1985 nahanni earthquakes Earthquake Engineering & Structural Dynamics 1988 16 5 676 10.1002/eqe.4290160504 46.2 cm/s Yes Yes None 1985 Nahanni earthquakes.jpg The 1985 Nahanni earthquakes is the name for a continuous sequence of earthquakes that began in 1985 in the Nahanni region of the Northwest Territories, Canada.Natural Resources Canada: Rock and Roll in the N.W.T.: The 1985 Nahanni Earthquakes https://web.archive.org/web/20090210053314/http://earthquakescanada.nrcan.gc.ca/historic_eq/20th/nahanni/nahanni85_e.php 2009-02-10 The largest of these earthquakes occurred on December 23, reaching 6.9 on the moment magnitude scale. This is one of the most significant earthquakes in Canada during the 20th century.Natural Resources of Canada: Significant Earthquakes in Canada https://web.archive.org/web/20081013063801/http://earthquakescanada.nrcan.gc.ca/historic_eq/20th/signif_e.php 2008-10-13 The earthquakes had a long succession of aftershocks and jolts. The earthquakes amazed both the general public and the earth science community and have been felt in the Yukon, Alberta, Saskatchewan, British Columbia, and southeastern Alaska. Geology and impact The earthquake sequence is commonly considered to consist of three major events over the span of almost three years: a w6.6 tremor on October 5, 1985, a w6.9 on December 23, 1985, and a w6.2 on March 25, 1988 UTC. All three events occurred within just several kilometers of each other. The epicenters of the mainshocks and aftershocks lie approximately 44 km (28 mi) west of the Camsell Bend of the Mackenzie River in the foreland fold and thrust belt of the northeastern American Cordillera. This part of the Cordillera is dominated by horizontal crustal compression (shortening) in a northeast direction, forming a large amount of thrust faults and folds. This region is relatively sparse of intense seismic activity—the Nahanni earthquakes generated much interest among seismologists due to being the only recorded earthquakes >M6.0 in this area. Between October 5, 1985 and March 25, 1988, 323 aftershocks were recorded, occurring in a roughly 60 km by 20 km zone.Ristau Johannes 1999 Applications of Synthetic Aperture Radar Interferometry in the Study of the Nahanni Earthquake Region https://www.collectionscanada.gc.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ45115.pdf MSc University of Manitoba The characteristics of aftershocks suggest that the rupture plane was a west-dipping low-angle thrust fault.Horner R. B. Wetmiller R. J. Lamontagne M. Plouffe M. 1990 A fault model for the Nahanni earthquakes from aftershock studies Bulletin of the Seismological Society of America 80 6A 10.1785/BSSA08006A1553 The earthquakes are interpreted to have occurred on unmapped faults in the vicinity of the Iverson Thrust Fault.Moon Wooil Won J.S. Li B. Slaney V. Roy Lamontagne Maurice 1991 Application of airborne C-SAR and SPOT image data to the geological setting of the Nahanni earthquake area https://www.researchgate.net/publication/278784157_Application_of_Airborne_C-SAR_and_SPOT_Image_Data_to_the_Geological_Setting_of_the_Nahanni_Earthquake_Area Canadian Journal of Remote Sensing 17 3 10.1109/igarss.1990.688947 The ground motion of the mainshock of December 23 was exceptionally intense, reaching a peak ground acceleration of more than 2 g and a peak ground velocity of over 40 cm/s. Due to the remote location of the epicenter, no structural damage was reported. The earthquake was felt 115 km (71 mi) away in Wrigley, where residents noted the effects of strong ground motion.Cassidy J. F. Rogers G. C. Lamontagne M. Halchuk S. Adams J. 2010 Canada’s Earthquakes: ‘The Good, the Bad, and the Ugly’ https://www.erudit.org/en/journals/geocan/2010-v37-n1-geocan37_1/geocan37_1art01/ Geoscience Canada 37 1 A massive rockslide was triggered by the w6.6 event on October 5, around 7 km (4 mi) northeast of the epicenter. The rockslide displaced a volume of approximately 7.6 million cubic meters of earth in the Mackenzie Mountain foothills.Ghahramani Negar Evans Stephen G. 2018 The 1985 earthquake-triggered North Nahanni rockslide, Northwest Territories, Canada: The co-seismic movement of a sedimentary rock mass conditioned by residual strength Engineering Geology 247 10.1016/j.enggeo.2018.10.015 See also List of earthquakes in 1985 List of earthquakes in Canada References Spectral scaling of the Nahanni earthquakes http://www.daveboore.com/pubs_online/1989bssa_ba89_nahanni.pdf D. Boore G. M. Atkinson 1989 Bulletin of the Seismological Society of America 79 6 1736–1761 10.1785/BSSA0790061736 An analysis of the 1985 Nahanni earthquakes http://www.bssaonline.org/content/78/2/590.abstract? R. J. Wetmiller R. B. Horner H. S. Hasegawa R. G. North M. Lamontagne D. H. Weichert S. G. Evans 1988 Bulletin of the Seismological Society of America 78 2 590–616 2014-04-24 2015-09-23 https://web.archive.org/web/20150923194938/http://www.bssaonline.org/content/78/2/590.abstract dead External links 512586 Category:1985 in Canada Category:Earthquakes in Canada Category:Natural disasters in the Northwest Territories Category:1985 earthquakes Category:Natural history of Alaska Category:Natural history of Yukon Category:Natural history of Alberta Category:Natural history of Saskatchewan Category:Natural history of British Columbia Category:December 1985 in Canada Category:1985 in the Northwest Territories Category:Earthquake clusters, swarms, and sequences Category:1985 disasters in Canada Category:1985 natural disasters in the United States