# On detecting and estimating multiple arrivals from underground nuclear explosions. Technical report

## Abstract

Nine explosions were used to study the problem of specifying the number and characteristics of the arrival phases of nuclear explosion. Tentative identification of the amplitudes and time delays of the multiple arrivals are given. The method used is to scan the likelihood (L) for a single reflection model over amplitude (a) and time delay (tau). The likelihood is constructed in the frequency domain using von Seggern and Blandford's (1972) source signal spectrum and a noise spectrum estimated from a time window preceding the signal. The results demonstrated that pP was present along with additional multiple arrivals indicated by other peaks in the likelihood function, L. In the case of MAST and PILEDRIVER, the likelihood estimate for tau was found to be clearly superior to tau = 1/f sub n, where f sub n is the first null frequency. The result for PILEDRIVER, tau = .15, is the first accurate estimate of tau for this event, and the shortest estimated delay time in the literature. The delay time for CANNIKIN, .55 sec, is significantly shorter than twice the observed uphole time: 1.0 sec. This result is unexplained, but it may be related to a change of reflection coefficient with frequencymore »

- Authors:

- Publication Date:

- Research Org.:
- Teledyne Geotech, Alexandria, VA (USA). Seismic Data Lab.

- OSTI Identifier:
- 5010106

- Report Number(s):
- AD-A-079531

- DOE Contract Number:
- F08606-78-C-0007

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; NUCLEAR EXPLOSION DETECTION; SEISMIC DETECTION; CHEMICAL EXPLOSIVES; DEPTH; SEISMIC ARRAYS; SEISMIC WAVES; DETECTION; DIMENSIONS; EXPLOSIVES; MEASURING INSTRUMENTS; 450300* - Military Technology, Weaponry, & National Defense- Nuclear Explosion Detection

### Citation Formats

```
Shumway, R H, and Blandford, R R.
```*On detecting and estimating multiple arrivals from underground nuclear explosions. Technical report*. United States: N. p., 1978.
Web.

```
Shumway, R H, & Blandford, R R.
```*On detecting and estimating multiple arrivals from underground nuclear explosions. Technical report*. United States.

```
Shumway, R H, and Blandford, R R. Thu .
"On detecting and estimating multiple arrivals from underground nuclear explosions. Technical report". United States.
```

```
@article{osti_5010106,
```

title = {On detecting and estimating multiple arrivals from underground nuclear explosions. Technical report},

author = {Shumway, R H and Blandford, R R},

abstractNote = {Nine explosions were used to study the problem of specifying the number and characteristics of the arrival phases of nuclear explosion. Tentative identification of the amplitudes and time delays of the multiple arrivals are given. The method used is to scan the likelihood (L) for a single reflection model over amplitude (a) and time delay (tau). The likelihood is constructed in the frequency domain using von Seggern and Blandford's (1972) source signal spectrum and a noise spectrum estimated from a time window preceding the signal. The results demonstrated that pP was present along with additional multiple arrivals indicated by other peaks in the likelihood function, L. In the case of MAST and PILEDRIVER, the likelihood estimate for tau was found to be clearly superior to tau = 1/f sub n, where f sub n is the first null frequency. The result for PILEDRIVER, tau = .15, is the first accurate estimate of tau for this event, and the shortest estimated delay time in the literature. The delay time for CANNIKIN, .55 sec, is significantly shorter than twice the observed uphole time: 1.0 sec. This result is unexplained, but it may be related to a change of reflection coefficient with frequency which is not included in the model. Comparison of theoretical and observed WWSSN long-period explosion P waves provides evidence for such a variable reflection coefficient. Fair to good agreement was obtained between predicted and observed explosion periods measured on WWSSN long-period film and on LRSM short-period data which was deconvolved to appear as if recorded on the WWSSN long-period system.},

doi = {},

url = {https://www.osti.gov/biblio/5010106},
journal = {},

number = ,

volume = ,

place = {United States},

year = {1978},

month = {5}

}