Paleoseismological evidence from lake sediments for recent movement on the Denali and other faults, Yukon Territory, Canada

Abstract

Most of the Pacific–North America plate motion in northwestern Canada and southeastern Alaska occurs along coastal faults that are the inland extension of the Queen Charlotte dextral transform fault. More ancient faults farther east, such as the Denali and Duke River faults, exhibit moderate earthquake activity and may be accommodating part of the Pacific plate motion. Paleoseismological results based on seismic resuspension of lake sediments, covering a period of up to 3000 years, show that the seismicity on the Denali–Duke River fault system is remarkably recent, spanning just the last three to five centuries. There is a northerly-trending zone of seismicity from the active Fairweather–Contact fault system on the coast, across to the part of the Denali fault that is currently, as well as prehistorically, active. This partial transfer eastward of Pacific plate motion may be analogous to a similar proposed transfer of motion northward to the Denali fault from the same Fairweather–Contact fault system, farther west in Alaska.