Abstract: Southwestern Yukon is a seismically active zone of crustal deformation including multiple large, dextral strike-slip fault systems with overlapping activity. In this study, we perform double-difference relocation to the USGS earthquake catalogue for this region to produce a relocated catalogue of 5536 seismic events above magnitude 1.5 from 2010–2021. The relocated catalogue demonstrates better spatial resolution of linear features and the removal of grid location artifacts in depth. The relocated catalogue has smaller travel time residuals and smaller residual standard deviations showing that the new catalogue has improved absolute locations. From bootstrapping, we estimate the location uncertainties for the relocated events to be on the order of 1.2–2.4 km in the horizontal direction and 1.5–2.1 km in the vertical direction. From the relocated events, we interpret new faults including a fault connecting the Totschunda and Denali faults, a connector fault between the Totschunda-Duke River fault system and the Fairweather fault, and multiple smaller faults connecting the Fairweather and Denali faults. The significantly reduced uncertainty in depth also permits constraining the seismicity predominantly to the uppermost 10 km of the crust.

Authors: Biegel, K., Gosselin, J. and Dettmer, J.

NTS Mapsheet(s): 105B, 105C, 105E, 105F, 105G, 105L, 105M, 115A, 115B, 115C, 115F, 115G, 115H, 115I, 115J, 115K, 115N, 115O, 115P

Citation: Biegel, K., Gosselin, J. and Dettmer, J., 2023. Preliminary double-difference relocation earthquake catalogue for southwestern Yukon centred along the Denali fault zone. In: Yukon Exploration and Geology 2022, K.E. MacFarlane (ed.), Yukon Geological Survey, p. 1–18, plus digital appendices.

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