Wood Anderson Magnitude Scale for Mt. Vesuvius

INGV - Osservatorio Vesuviano

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.