Magnitude: The relation of ML to mbLg

The m bLg magnitude developed by Nuttli (1973) for the Central United States is adapted to other regions of the world by incorporating a specific term for the spatial coefficient of anelastic attenuation γ. Using region-specific γ values, m bLg values are determined for earthquakes occurring near the WWSSN stations BKS, GSC, and DUG. A comparison of the m bLg values with published M L magnitudes shows that these two magnitude scales are essentially equivalent between magnitudes 3 to 5. Because of this observation, we now have a direct way of comparing Eastern and Western United States earthquake sizes for the purpose of adapting western strong motion data bases to the east and also for understanding teleseismic magnitude biases.