Array analysis of regional Pn and Pg wavefields from the Nevada Test Site

Technical Report · Sat Jun 01 04:00:00 EDT 1991

DOI:https://doi.org/10.2172/5231875· OSTI ID:5231875

Leonard, M A ^[1]

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1. California Univ., Berkeley, CA (United States). Dept. of Geology and Geophysics Lawrence Berkeley Lab., CA (United States)

Small-aperture high-frequency seismic arrays with dimensions of a few kilometers or less, can improve our ability to seismically monitor compliance with a low-yield Threshold Test Ban Treaty. This work studies the characteristics and effectiveness of array processing of the regional Pn and Pg wavefields generated by underground nuclear explosions at the Nevada Test Site. Waveform data from the explosion HARDIN (m{sub b} = 5.5) is recorded at a temporary 12-element, 3-component, 1.5 km-aperture array sited in an area of northern Nevada. The explosions VILLE (m{sub b} = 4.4) and SALUT (m{sub b} = 5.5) are recorded at two arrays sited in the Mojave desert, one a 96-element vertical-component 7 km-aperture array and the other a 155-element vertical-component 4 km-aperture array. Among the mean spectra for the m{sub b} = 5.5 events there are significant differences in low-frequency spectral amplitudes between array sites. The spectra become nearly identical beyond about 6 Hz. Spectral ratios are used to examine seismic source properties and the partitioning of energy between Pn and Pg. Frequency-wavenumber analysis at the 12-element array is used to obtain estimates of signal gain, phase velocity, and source azimuth. This analysis reveals frequency-dependent biases in velocity and azimuth of the coherent Pn and Pg arrivals. Signal correlation, the principal factor governing array performance, is examined in terms of spatial coherence estimates. The coherence is found to vary between the three sites. In all cases the coherence of Pn is greater than that for Pg. 81 refs., 92 figs., 5 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5231875
• Report Number(s): LBL-31035; ON: DE92000840
• Country of Publication: United States
• Language: English

Related Subjects

350300 -- Arms Control-- Verification-- (1987-)
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
450300* -- Military Technology
Weaponry
& National Defense-- Nuclear Explosion Detection
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
AMPLITUDES
COMPILED DATA
COMPUTER GRAPHICS
COMPUTERIZED SIMULATION
DATA
DATA ANALYSIS
DETECTION
DETONATION WAVES
EXPLOSIONS
FORECASTING
GROUND MOTION
INFORMATION
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MONITORING
MOTION
NATIONAL ORGANIZATIONS
NEVADA TEST SITE
NON-PROLIFERATION TREATY
NUCLEAR EXPLOSIONS
NUMERICAL DATA
READOUT SYSTEMS
SEISMIC ARRAYS
SEISMIC DETECTION
SEISMIC P WAVES
SEISMIC S WAVES
SEISMIC WAVES
SHOCK WAVES
SIMULATION
SPECTRA
TREATIES
UNDERGROUND EXPLOSIONS
US DOE
US ORGANIZATIONS
VARIATIONS