Recalibration of the magnitude scales at Campi Flegrei, Italy, on the basis of measured path and site and transfer functions

New duration-based local (M(L)) and moment (M(w)) magnitude scales are obtained for the Campi Flegrei area through analysis of a dataset of local volcanotectonic earthquakes. First, the S-wave quality factor for the investigated area was experimentally calculated, and then the distance-correction curve, logA(0)(r), to be used in the Richter formula M(L) = logA(max) - logA(0)(r), was numerically estimated by measuring the attenuation properties and, hence, propagating a synthetic S-wave packet in the earth medium. The local magnitude scale was normalized to fit the Richter formula that was valid for Southern California at a distance of 10 km- M(L) was estimated by synthesizing Wood-Anderson seismograms and measuring the maximum amplitude. For the same dataset, the moment magnitude was obtained from S-wave distance-corrected and site-corrected displacement spectra. Comparisons between local and moment magnitudes determined, along with the old duration magnitude (M(D)) routinely used at the Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Vesuviano, are presented and discussed. Moreover, the relationships between M(L) and M(w) calculated for two reference sites are also derived.