Wood Anderson Magnitude Scale for Mt. Vesuvius

Abstract

A Mathcad-8 program to calculate a revised magnitude scale is presented. An application to Mt. Vesuvius is included as a program test. Wood-Anderson seismograms for 131 local earthquakes recorded at station BKE (Osservatorio Vesuviano seismic network) were synthesized to estimate local magnitude from the original definition: Ml=log Amax(D) - logAo(D) The distance correction logAo(D) was empirically determined simulating a wave packet which propagates in a structure with assigned Q. Moment magnitude (calculated both with Kanamori and Tatcher-Hanks formulas) was also determined from the displacement spectra. Finally a relation between Wood-Anderson magnitude and duration magnitude was derived, allowing the estimate of local magnitude from the duration of the earthquake.