EFFECT OF SOURCE DEPTH CORRECTION ON THE ESTIMATION OF EARTHQUAKE SIZE

The relationship between surface wave magnitude, M(s), and seismic mom ent, M(0), of earthquakes is essential for the estimation of seismic r isk in any region. In the hypothesis of constant stress drop, theoreti cal models predict that Log M(0) and M(s) are related by a linear law. The slope most commonly found in the literature is around 1.5. Here w e show that the application to the M(s) values of the necessary correc tion for the focal depth, gives a general increment of the correlation coefficient, and that a slope around 1.0 is consistent with the globa l data, while for regionalized data it can vary from about 1.0 to 2.0.