Infrasound Signals as Basis for Event Discriminants
Abstract
Herein we summarize the first several months' effort in this research project of calculating the near-field infrasound signals generated by ground motion sources such as underground tests and earthquakes. Our approach is a direct application of the Rayleigh integral to the ground motion acceleration as seen by an observer at altitude near the source. The numerical integration is straightforward; however, the specification of the acceleration time history may be more difficult. Results of such calculations can, with good ground motion models for underground tests and earthquakes, be used to look for differences in the near-field infrasound signals that would be the basis for discriminants. So far, the work has concentrated on getting basic codes in place and on modeling underground test signals, which will be the emphasis of this contribution. There are 34 events for which model ground motion parameters were derived, earlier by others, from the ground motion data. We now have access to the Nevada Test Site (NTS) ground motion database. This can help in improving ground motion models for underground tests. Another new development was the successful application of a two-dimensional time-domain finite-difference code to this problem. The code was run with a time dependent velocity boundary condition and to a problem time of 40 seconds showing the acoustic signal in the 12 km by 12 km domain. Results from this code can be used to benchmark other codes. Another planned use for this near-field modeling work is to provide realistic initial conditions for long-range acoustic propagation codes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2007
- Accession Number
- ADA519418
Entities
People
- Rodney W. Whitaker
Organizations
- Los Alamos National Laboratory