Theoretical Analysis of Narrow-Band Surface Wave Magnitudes
Abstract
A major problem with time domain measurements of seismic surface waves is the significant effect of non- dispersed Rayleigh waves (Airy phases) which can occur at both regional and teleseismic distances. This paper derives a time domain method for measuring surface waves with minimum digital processing, using zero-phase Butterworth filters. This method can effectively measure surface wave magnitudes at both regional and teleseismic distances, while ensuring that the magnitudes are unbiased with respect to accepted formulae at reference periods, thus providing historical continuity. For applications over typical continental crust, the proposed magnitude equation is: M(subS(b)=log(measured filtered amplitude)+1/2log(sin(delta))+0.0031(20/period)(exp2.3) delta-0.66log (20/period)-log(Butterworth filter corner frequency)-0.43 where a(sub b)=Measured filtered amplitude, T=period, and f(sub c)=.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 30, 2004
- Accession Number
- ADA428925
Entities
People
- David R. Russell