The Frequency of Very Large Earthquakes

Observational data relating surface wave magnitude M sub s to seismic moment M sub o are used to convert a well-known frequency-M sub s plot into a frequency-M sub o relationship, which turns out to be remarkably linear. There is no evidence of an upper bound to M sub o, on the basis of presently available. The possibly exists that extremely large earthquakes (M sub o = 10 to the 31th power dyne-centimeters or greater) may occur from time to time.