Abstract: A seven station seismograph array operated at two sites on the western segment of the Duke River Fault between May 22, 1987 and August 13, 1987 detected 146 earthquakes of which 44 were located. Distribution of microearthquake epicentres, S-P times and moderate earthquake epicentres delineate three zones of seismicity. Most microseismicity is confined to a 15 km wide central zone, parallel to the Duke River Fault and centred approximately 5 km north of it, where shallow and midcrustal microearthquake focii are centred beneath structures deforming the Tertiary cover. Faulting here is well constrained to oblique thrusting on a slip plane striking parallel to the Cement Creek fault. A northern zone of shallow focus microseismicity is centred on the Woverine Plateau and the valley of the White River. A southern zone of microearthquake focii centred on the Icefield Ranges delineates an unmapped fault, 40 km long and striking west from known faults south of the Duke River Fault. The distribution of epicentres and a composite focal plane solution suggest that reverse faulting with southward vergence is occurring in this zone. The results of this study and the historical record of epicentres suggest that the Totschunda and Duke River Fault segments of the Denali Fault System are structurally linked and that no connection between the Denali Fault System and the Pacific margin is in this area.

Authors: Power, M.A.

NTS Mapsheet(s): 115F, 115G

Citation: Power, M.A., 1988. Microearthquake Seismicity on the Duke River, Denali Fault System. In: Yukon Geology Volume 2, J.G. Abbott, Exploration & Geological Services Division, Indian & Northern Affairs Canada, p. 61-68.

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