Earthquake Magnitude and Complex Faulting Process

Abstract

Earthquake magnitude has been determined for earthquakes since the end of the 19th century. More recently magnitude of local earthquakes has also been determined, using a variety of methods with different kinds of data. The current trend in seismology is to describe earthquakes in terms of the source parameters discussed previously. However, earthquake magnitude is a parameter widely used as a measure of both large and small earthquakes and is the only parameter for comparing the strength of historical earthquakes with recent ones. We will study earthquake magnitude, considering the long-period and the short-period approximations of the complex faulting process. The long-period approximation describes the theoretical relationship between earthquake magnitude and macroscopic source parameters, whereas the short-period approximation clarifies the relationship between magnitude and stochastic source parameters.