9628494 Masters This research is a continuation of the definition of the large- scale structure of the Earth by means of the use of long-period and broad-band digital data to constrain elastic and inelastic structure. The current emphasis is on pushing the analysis to smaller length scales and on incorporating the effects of anisotropy. Seismic data sets will be expanded to improve global coverage, locally densify to the point that regional-scale studies are viable, and improve the precision of attenuation measurements. The mean travel times obtained from such studies are also useful in the development of new one-dimensional models and in the evaluation of the effect of the absorption band on the frequency-dependence of travel times. New data sets will be developed based on the polarization or particle motion of body waves; they are expected to be sensitive to small-scale structure and anisotropy. Research will be done on new parameterizations which allow regional densification to accommodate the improved resolution of the new data sets. ***
