AN EXTENSION OF CREEPEX DEFINITION TO LOCAL EARTHQUAKE MAGNITUDES: ITALY

Abstract

The systematic deviation of the magnitude of a single earthquake from the linear orthogonal regression between local magnitude $M_L$ and coda duration magnitude $M_d$ calculated for the whole region is used as a measure of the frequency content of Italian earthquakes. Predominantly high-frequency events are found in two areas of Quaternary tectonic shortening: northern Central Italy and the Calabrian Arc. This result, confirmed by two independent statistical tests, is in agreement with the global creepex pattern obtained from a study of the regression between body wave magnitude $m_b$ and surface wave magnitude $M_S$: in seismic energy release, there is a systematic shift to higher frequencies for subduction zones and to lower frequencies for spreading zones.

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Computational Seismology, Vol. 3.