Open AccessObservation and modelling of fault‐zone fracture seismic anisotropy – II. P ‐wave polarization anomalies
Author(s) -
Li Y.G.,
Leary P. C.,
Aki K.
Publication year - 1987
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1987.tb05240.x
Subject(s) - slowness , geology , anisotropy , isotropy , seismogram , seismic anisotropy , shear wave splitting , ray tracing (physics) , seismology , shear (geology) , s wave , polarization (electrochemistry) , geophysics , physics , optics , mantle (geology) , petrology , chemistry
Summary. In Part I of this paper we modelled shear‐wave splitting observed in crystalline rock bordering an active, normal fault‐zone at Oroville, California, with Červený's ray‐tracing system applied to anisotropic heterogeneous media using Hudson's formulation of elastic constants for a medium containing aligned cracks. In Part II we use the ray‐tracing results of Part I to quantitatively interpret P ‐wave polarization anomalies observed in the three‐component seismograms recorded in the Oroville fault zone. We show that the eigenvectors of the first‐order Christoffel tensor defined by the ray‐tracing slowness vector and Hudson's first‐order anisotropic corrections to the isotropic elastic tensor correctly account for P ‐wave first motion that deviates from the ray vector.