Waveguide Controls on Regional Waves
Abstract
One of the first-order challenges associated with non-proliferation monitoring is to understand short-period seismic wave energy partitioning for different sources in diverse geological environments, many of which have no prior nuclear explosion history. We have developed a promising new approach of empirical calibration of regional phase energy partitioning based on relationships with readily observable surface topographic characteristics. Analysis of nuclear test recordings in the former Soviet Union under prior DARPA- and AFOSR-sponsored contracts revealed very strong consolations between surface topographic roughness and/or average elevation with energy partitioning in Pn, Sn, and Lg phases at regional and upper mantle distances. Surface topography appears to provide, at least over many Eurasian paths, a surface observable that tracks gross variations in the waveguide properties that control regional phases. Significant reduction in the scatter of measurements such as Pn/Lg or Sn/Lg can be achieved by empirical correction for path topography. Reduced scatter in such discriminant measures offers the possibility of enhanced discriminant and yield estimation performance for non-proliferation applications. We will analyze additional explosion and earthquake data sets in Eurasia, as well as earthquake data sets in the Western United States and Middle East, to establish whether surface topographic corrections are generally useful for regional phase analysis. Simultaneously, we will perform numerical investigations of the effects of surface topography on regional phase energy partitioning to lead to a quantitative understanding of the strong empirical relations that we have discovered.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 20, 2000
- Accession Number
- ADA380954
Entities
People
- Thorne Lay
Organizations
- University of California, Santa Cruz