| The Lost River fault system is part of the northern Basin and Range province. Though its northern mapped trace ends east of Challis, Idaho, a linear cluster of seismicity occurred in 2014-2016 five km to the northwest. This work applied remote sensing methods to evaluate whether there is a previous, unmapped active fault north of Challis responsible for recent seismicity and to determine how the fault system changes toward its northern extent. Preliminary mapping was unable to identify an active fault. However, investigation of a southern study area using an unmanned aircraft system
(UAS) identified a fault trace that may represent an unmapped portion of the Lost River fault system. These results suggest that: 1) displacement along the northern trace of the fault system occurs along multiple, lower fault strands; and 2) a blind fault may be responsible for recent seismicity beyond the northern extent of the fault system. |