Y. Huang

The magnitude‐frequency distribution (MFD) describes the relative proportion of earthquake magnitudes and provides vital information for seismic hazard assessment. The b ‐value, derived from the MFD, is commonly used to estimate the probability that a future earthquake will exceed a specified magnitude threshold. Improved MFD and b ‐value estimates are of great importance in the central and eastern United States where high volumes of fluid injection have contributed to a significant rise in seismicity over the last decade. In this study, we recalculate the magnitudes of 8,775 events for the 2011 Prague, Oklahoma sequence using a relative magnitude approach that depends only on waveform data to calculate magnitudes. We also compare the distribution of successive magnitude differences to the MFD and show that a combination of the magnitude difference distribution (MDFD) and relative magnitudes yields a reliable estimate of b ‐value. Using the MDFD and relative magnitudes, we examine the temporal and spatial variations in the b ‐value and show that b ‐value ranges between ∼0.6 and 0.85 during the aftershock sequence for at least 5 months after the M 5.7 mainshock, though areas surrounding the northeast part of the sequence experience higher b ‐values (0.7–0.85) than the southwestern part of the Meeker‐Prague fault where b ‐value is the lowest (0.6–0.7). We also identify a cluster of off‐fault events with the highest b ‐values in the catalog (0.85). These new estimates of MFD and b ‐value will contribute to understanding of the relations between induced and tectonic earthquake sequences and promote discussion regarding the use of b ‐value in induced seismic hazard estimation.