D. Reymond et Ea. Okal, Preliminary determination of focal mechanisms from the inversion of spectral amplitudes of mantle waves, PHYS E PLAN, 121(3-4), 2000, pp. 249-271
We present a method for the preliminary determination of focal mechanisms (
PDFM). based on the inversion of deviatoric moment tensor components from d
epleted datasets of mantle wave spectral amplitudes. The latter are found t
o be largely insensitive to errors in epicentral estimates, which can hampe
r the inversion of the full complex spectrum under real-time operational co
nditions. Robust solutions can be obtained from Rayleigh wave spectra at as
few as three stations, and from a combination of Rayleigh and Love waves a
t only two stations, provided they sample 60 degrees in azimuth. The system
atic application of this method to a dataset of 43 large earthquakes during
1996-1999 yielded mechanisms rotated an average of only 17 degrees from th
e published Harvard CMT, a figure comparing favorably with the case of othe
r catalogues, such as the USGS moment tensor solutions. (C) 2000 Elsevier S
cience B.V. All rights reserved.