DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click
HERE to register or log in.
Accession Number:
ADA516259
Title:
Explosion Source Model Development in Support of Seismic Monitoring Technologies: New Models Accounting for Shock-Induced Tensile Failure
Descriptive Note:
Conference paper
Corporate Author:
LOS ALAMOS NATIONAL LAB NM
Report Date:
2008-09-01
Pagination or Media Count:
10.0
Abstract:
The traditional source model for long-period seismic waves from nuclear explosions consists of a monopole releasing tectonic strain. Tectonic release has been studied since the 1960s, and numerous studies have shown that linear superposition of monopole double-couple sources can explain many observations of Rayleigh and Love waves. Free surface interactions and the dynamics of shock-wave rebound are responsible for modes of tensile failure which can also lead to permanent deformations affecting long-period excitation. Indeed, the vast majority of nuclear explosions worldwide were conducted under containment conditions that facilitated shock-induced, deep-seated tensile failure. A new source model, which is a superposition of monopole tectonic release shock-induced tensile failure, is proposed, the latter source represented by a compensated-linear-vector dipole CLVD with vertical axis of symmetry. This CLVD source does not excite Love waves. I draw upon the Toksoz-Kehrer 1972 model for tectonic release where F is an index measuring long-period source strength of the release relative to monopole moment MI. A new index K, analogous to F, is introduced, providing a relative measure of MCLVD, the source strength of tensile failure. MCLVD vanishes for K 1, and is 0 in the case of extensional deformation along the vertical axis, e.g., K 1. Rayleigh waves from the CLVD destructively interfere with waves from the monopole, and polarity reversals occur on all azimuths for K 3 in Poisson media. Most Nevada Test Site NTS observations support 1 K 3, and as such the new model predicts lower Ms compared to the traditional model involving just tectonic release. This effect of tensile failure on Ms improves mb - Ms discrimination and suggests that anomalously large Ms compared to mb for the North Korean test of 9 October 2006 is due to the absence of tensile failure on this explosion.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
