Global Seismic Nowcasting with Shannon Information Entropy

ABSTRACT: Seismic nowcasting uses counts of small earthquakes as proxy data to estimate the current dynamical state of an earthquake fault system. The result is an Earthquake Potential Score (EPS) that characterizes the current state of progress of a defined geographic region through its nominal earthquake “cycle&rdquo". The count of small earthquakes since the last large earthquake is the natural time that has elapsed since the large earthquake (Varotsos et al., 2006). In addition to natural time, there are other ways to characterize small earthquakes that include other types of data. One of these is Shannon Information Entropy ("information"), an idea that was pioneered by Shannon (1948). As a first step to adding seismic information into the nowcasting method, we develop a method for incorporating magnitude information into the natural time counts by using event self-information. We find in this first application of seismic information entropy that the EPS values are similar to the values using only natural time.