High-Precision Earthquake Catalog for Minto Flats Fault Zone, Central Alaska, Reveals Complex and Conjugate Faulting

ABSTRACT The Minto Flats fault zone (MFFZ) in central Alaska is a left-lateral strike-slip fault system situated between the continental-scale right-lateral Denali and Kaltag-Tintina faults. The MFFZ has the potential to generate magnitude 7 earthquakes, and it hosted a magnitude 6 earthquake in 1995. It has also produced exotic events, such as very-low-frequency earthquakes and nucleation signals. We use network-matched filtering and relative earthquake relocation techniques to derive a detailed catalog of earthquake locations for the MFFZ. The catalog spans from August 2014 to December 2019, a time period including 13 temporary seismic stations in the region. Our results provide the most complete catalog for the MFFZ and include deeper events, clusters of shallow seismicity, and a complex and segmented fault structure not observed in the original regional catalog. We document right-lateral strike-slip faulting, conjugate to the main northeast-striking left-lateral faults of the MFFZ. Below Nenana basin, the relocated seismicity reveals northwest-dipping left-lateral faults, supporting the inference that deep crustal active faulting is associated with recent basin deformation.