An Empirical Formula to Classify the Quality of Earthquake Locations

Abstract

Providing a quantitative estimate of earthquake location quality is not a simple task. Traditional methods, used in literature, are not exhaustive and depend on a subjective point of view, because they consist of empirical choice of quality thresh- olds of different estimators of location uncertainty. However, we notice that these estimators are correlated with one another, implying the need to combine them to obtain a numerical and impartial estimate of the quality of a seismic location. Therefore, we provide a formula that associates a quality factor (q f ) value with a seismic location, which is based on the combination of a set of uncertainty estimators, suitably normalized. We apply the criterion to two different-type and different-scale earthquake catalogs, located by two different methods, obtaining encouraging results. The q f parameter definition is a fast, simple, and objective instrument to provide a user-friendly classification of location quality. Thus, the q f could represent a powerful tool for routine monitoring location computation.