EXTENSION OF GLOBAL CREEPEX DEFINITION (M(S)-M(B)) TO LOCAL STUDIES (M(D)-M(L)) - THE CASE OF THE ITALIAN REGION

Creepex, defined as the systematic deviation of the magnitude of a sin gle earthquake from the linear orthogonal regression between local mag nitude M(L) and coda duration magnitude M(d), calculated for the whole region, is used as a measure of the frequency content of the seismic sources in the Italian region. Predominantly high-frequency events are found in the two areas of Quaternary tectonic shortening in North-Cen tral Italy and in the Calabrian Arc. This result, confirmed by two ind ependent statistical tests, is in agreement with the global pattern ob tained from the study of the regression between body-wave magnitude, m (b), and surface-wave magnitude M(s): systematic shift to high frequen cies in the energy release of seismic sources located in subduction zo nes and to low frequencies in zones of spreading. The analysis of the correlation between the patterns of heat flow and of seismic source sp ectral properties indicates that these source properties, in general, do not reflect thermal conditions in the lithosphere, but rather repre sent the result of tectonic processes.