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Extension of global creepex definition ( M s ‐ m b ) to local studies ( M d ‐ M L ): the case of the Italian region
Author(s) -
Panza G.F.,
Prozorov A.G.,
Pazzi G.
Publication year - 1993
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.1993.tb00240.x
Subject(s) - magnitude (astronomy) , geology , seismology , coda , lithosphere , subduction , tectonics , geodesy , physics , astronomy
Creepex, defined as 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 the seismic sources in the Italian region. Predominantly high‐frequency events are found in the two areas of Quaternary tectonic shortening in North‐Central Italy and in the Calabrian Arc. This result, confirmed by two independent statistical tests, is in agreement with the global pattern obtained from the study of the regression between body‐wave magnitude, m b , and surface‐wave magnitude M s : systematic shift to high frequencies in the energy release of seismic sources located in subduction zones and to low frequencies in zones of spreading. The analysis of the correlation between the patterns of heat flow and of seismic source spectral properties indicates that these source properties, in general, do not reflect thermal conditions in the lithosphere, but rather represent the result of tectonic processes.