Large Surface-Rupturing Earthquakes and a >12 kyr, Open Interseismic Interval on the Tintina Fault, Yukon

Abstract

We present the first geomorphic evidence for successive, surface-rupturing earthquakes throughout the Quaternary on the Tintina fault in the Yukon Territory, northwestern Canada. A ∼130-km-long series of scarps and pressure ridges offset 2.6 Ma and 132 ka landforms by ∼500–1,500 m and 65–85 m, respectively, indicating a dextral slip rate of ∼0.2–0.8 mm/yr. However, early Holocene terraces are undeformed across the fault, implying that the elapsed time since the most recent earthquake is >12 kyr and that the fault may be nearing the end of a long interseismic cycle. A minimum slip deficit of ∼6 m has likely accrued since the last major surface rupture, and future earthquakes could exceed M_w 7.5. These results highlight the hazards of earthquakes on mature, low-slip-rate intraplate faults, which may have exceptionally long recurrence intervals, elude instrumental networks, and lack a distinct surface expression due to landscape resetting.