LOCALIZED DILATANCY IN ROCK OBSERVED BY SEISMIC COMPUTER TOMOGRAPHY

Seismic Wave Propagation in Fractured Carbonate Rock

Laboratory experiments were performed on cubic samples of Austin Chalk to investigate the effect of fabric-induced anisotropy on the interpretation of fracture specific stiffness. The experimental results found that the fabric-induced layering complicates the interpretation of fracture specific stiffness. Seismic measurements from a sample with small layers (i.e., spacing and thickness) show th...

Seismic Tomography

The inversion of seismic travel-time data for radially varying media was initially investigated by Herglotz, Wiechert, and Bateman (the HWB method) in the early part of the 20th century [1]. Tomographic inversions for laterally varying media began in seismology starting in the 1970's. This included early work by Aki, Christoffersson, and Husebye who developed an inversion technique for estimati...

Localized seismic deformation in the upper mantle revealed by dense seismic arrays.

Seismicity along continental transform faults is usually confined to the upper half of the crust, but the Newport-Inglewood fault (NIF), a major fault traversing the Los Angeles basin, is seismically active down to the upper mantle. We use seismic array analysis to illuminate the seismogenic root of the NIF beneath Long Beach, California, and identify seismicity in an actively deforming localiz...

Diffraction and seismic tomography

Diffraction tomography is formulated in such a way that the data ( t ravel t ime4r waveform perturbations) are related to the medium perturbations through the sum of two terms. The first term is the ray integral of ordinary tomography and involves only phase perturbations. The additional diffraction term involves both phase and amplitude perturbations. The diffraction term is linear in the grad...

Seismic Traveltime Tomography 1