We present a simple and robust approach to estimate moment magnitude (M) for events of M<6 from regional seismographic observations (vertical component), recorded in the distance range from 100 to 400 km. M can be estimated from 1‐Hz response spectral amplitudes for events in North America with an uncertainty (standard deviation of residuals) of <0.2 units in most regions, using the simple relationships provided herein. Advantages of the method are that it allows for consistent estimation of M across regions, and that it provides relationships that are consistent with the predictions of a stochastic point‐source model for typical regional attenuation models.

Online Material: Table of events for which the moment magnitude was estimated.

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