Attenuation and Source Studies in Northern Eurasia.
Abstract
A new inversion method, in which the frequency dependence of shear wave internal friction (Q sub mu to the -1) is allowed to vary with depth, was developed and applied to selected Rayleigh wave attenuation data in the Basin and Range Province of the southwestern United States. Models were further constrained to satisfy observed values of Q and the frequency dependence of Lg waves in that region. Many models can explain those two data sets within their uncertainties, but at 1 Hz most have low values of Q sub mu (50-80) in the upper 8 km of the crust, rapidly increasing values to about 1000 at mid-crustal depths, and decreasing values at greater depths. Models which include a layer of higher Q values (80-150) in the upper few km of the crust, overlying a region of low Q values, cannot be predicted by the data of this study. Models for which the frequency dependence is low (0.0-0.1) in the upper crust best explain the available data. In the lower crust that frequency dependence may be substantial and leads to models in which Q sub mu may be an order of magnitude lower (approx. 100) at a period of 100 s than it is a 1 s ( approx. 1000).
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 30, 1992
- Accession Number
- ADA259323
Entities
People
- Brian J. Mitchell
- J. K. Xie
Organizations
- Saint Louis University