The Mineral, Virginia (USA), earthquake occurred at 17:51:3.9 UTC (Coordinated Universal Time) on 23 August 2011; the hypocenter was at 37.905°N, 77.975°W and depth was 8 km. The widely reported moment magnitude (M_w) was 5.7 ± 0.1. The m_b (teleseismic short-period) magnitude estimated here using 26 global network stations is 5.77 ± 0.23, in agreement with m_b values reported by national and international data centers, and not significantly different from M_w. However, the m_bLg magnitude of the earthquake determined here using 386 stations in eastern North America is 6.28 ± 0.26. The m...