The Complexity of the 2018 Kaktovik Earthquake Sequence in the Northeast of the Brooks Range, Alaska
Guangyu Xu, Caijun Xu, Yangmao Wen, Wei Xiong, Sotiris Valkaniotis
Abstract
Abstract We use mainly geodetic observations to constrain the fault geometry and coseismic distribution of the 2018 Kaktovik earthquake sequence, Alaska. We find that at least three faults were activated. The earthquake sequence ruptured mainly an ESE‐striking, SSW‐dipping strike‐slip fault and a secondary rupture on an SE‐striking, SW‐dipping normal fault. Slip also occurred on a small SSW‐striking fault plane, which is found first in geodetic data and further verified with geological data and focal mechanism solutions. We also map 6 months of postseismic deformation and find obvious displacements in the center of the Sadlerochit Mountains. A geological model is proposed to interpret the relationship between this earthquake sequence and the regional structure. We suggest that the 2018 Kaktovik earthquake sequence may first have occurred on a fault unknown prior to the mainshock and triggered slip on both the pre‐existing ramp structure below the Sadlerochit Mountains and a secondary structure.