Estimation of earthquake magnitude from mean MM IV isoseismal radius

Abstract The formula: M L = 1.06 ln R (IV) + 0.16 provides a quick and simple means of estimating the Richter magnitude, M L , of an earthquake from the mean MM IV isoseismal radius, R (IV). It approximates M L usually to half a magnitude or better, and provides a satisfactory method for estimating the magnitude of many larger ( M L ≥ 3.8) Australian earthquakes for which a radius of perceptibility cannot be determined accurately. As the formula was derived from eastern Australian earthquake data, its applicability should be tested before using it in other regions.