Aeromagnetic Data Reveal Potential Seismogenic Basement Faults in the Induced Seismicity Setting of Oklahoma

Abstract

Abstract New aeromagnetic survey data collected over north central Oklahoma image possible seismogenic faults in the crystalline basement. Linear earthquake sequences associated with induced seismicity suggest the reactivation of ancient basement faults, but few of these sequences are aligned with mapped faults. The new data show many earthquake sequences aligned with linear magnetic gradients or offsets between anomalies, while mapped faults, which mainly describe sedimentary cover, show limited correspondence with either. This strongly suggests significant structural differences between the crystalline basement and sedimentary cover. Furthermore, while the earthquakes are occurring on reactivated ancient faults, most of these faults have likely been inactive for millions of years. The magnetic data exhibit many gradient lineaments that are optimally oriented for fault slip, and the earthquake data suggest additional optimally oriented faults. Together these data suggest the presence of potentially numerous seismogenic faults throughout the region, which may contribute to high levels of induced seismicity.