Scattering Attenuation in Fractally Homogeneous Random Media,
Abstract
Much of seismic nuclear monitoring depends on a proper understanding of attenuation and scattering of regional seismic waves. This report seeks to characterize wave scattering from both an observational and theoretical approach. A theory of wave propagation in fractally homogeneous random media is developed and applied to southern Tibet in order to quantify the analytical and statistical properties of crust and upper lithosphere heterogeneity. Seismic velocity heterogeneity is modeled by a self-affine band limited random fractal. An approximation to multiple scattering theory yields a relationship between the exponent of the frequency dependent scattering quality factor Q and the fractal dimension of velocity iso-surfaces. In this study, the attenuation quality factor of P-waves, Qp, is calculated for southern Tibet and the implications for the fractal dimension of the velocity field are discussed. In addition, the topic of intermittent heterogeneity is introduced. The generalization of the model to fractally homogeneous media implies that scattering attenuation measurements are characterized by two fractal dimensions: one related to the self-affinity of the velocity field and the other related to the metric of the space which the field occupies. Within a fractal random media model, the attenuation calculation for southern Tibet yields a fractal dimension of velocity iso-surfaces of D = 9/4 which implies the existence of complex large-scale structure in the upper lithosphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 14, 1995
- Accession Number
- ADP204461
Entities
People
- C. Reese
- J. Ni
- T. Hearn
Organizations
- New Mexico State University