Abstract

An important part of the preparation and homogenization of the seismic catalog used in the recent seismic hazard assessment study of Spain is the development of relationships among the different scales used to measure earthquake size. The objective is to convert all earthquake size data in the original catalog to a single magnitude scale, the moment magnitude M w, in order to have a set of events with an uniform comparable size measurement. These new relationships are based on regression analysis between M w and the other units used in the catalog in different epochs. The reduced major axis regression scheme is used, because it is the most suitable method for symmetric treatment of the variables involved in the fits. The new relationships obtained for Spain, M w as a function of m bLg; M w as a function of m b; and M w as a function of I max, are presented and their applicability limits and accuracy are discussed. The results obtained could have other practical uses in regional seismicity analysis.