A method of estimating magnitude of local earthquakes from signal duration

Abstract

Richter magnitude of local earthquakes may be conveniently estimated from signal duration using an empirical formula: M -0.87 + 2.00 log(r) + 0.0035 A A where M is an estimate of Richter magnitude, T, signal duration in seconds, and A, epicentral distance in kilometers. This magnitude scale was established by analyzing the relation between Richter magnitude, signal duration, and epicentral distance for 351 earthquakes in central California.