Effects of heterogeneities on the propagation, scattering and attenuation of seismic waves and the characterization of seismic source. Final report, 1 December 1982-30 November 1985

Technical Report · Tue Jan 01 00:00:00 EST 1985

OSTI ID:6086721

Aki, K; Cormier, V F; Toksoz, M N

During this reporting period, work was completed on testing alternative measures of body-wave magnitude. It was found that alternative measures of body waves magnitude often exhibit as much scatter as classical measures of magnitude, although coda magnitudes usually have slightly less scatter than spectral and classical magnitudes. In the cases investigated, these differences were usually not statistically significant. Another completed task was an investigation of the intrinsic attenuation of the Earth's mantle selected paths from the Sea of Okhotsk to Regional Seismic Test Network (RSTN) and Global Digital Seismic Network (GDSN) Stations in North America. It was concluded that the intrinsic attenuation in the mantle beneath eastern North America is both depth and frequency dependent and that spectral and time domain studies of attenuation can be reconciled in the frequency band up to 2 Hz. The focus of the project was then divided between source problems related to scattering and seismic wave propagation in three-dimensional, heterogeneous media. A significant result was that short period and broadband waveforms can improve the depth-resolution-determined earthquakes and underground nuclear explosions, forming a powerful discriminant. Scattering was studied theoretically and observationally. The significant result of that work is that the Earth's lithosphere must possess multiple scales of heterogeneity in order to explain both the amplitude and phase fluctuations at large arrays as well as the shapes of local S coda.

• Research Organization: Massachusetts Inst. of Tech., Cambridge (USA). Earth Resources Lab.
• OSTI ID: 6086721
• Report Number(s): AD-A-182752/6/XAB
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
EARTHQUAKES
SEISMIC DETECTION
NUCLEAR EXPLOSION DETECTION
SEISMIC ARRAYS
SEISMIC WAVES
WAVE PROPAGATION
ATTENUATION
DEPTH
DIGITAL SYSTEMS
EARTH MANTLE
NORTH AMERICA
RESOLUTION
SCATTERING
SEISMOLOGY
SPECTRA
UNDERGROUND
VARIATIONS
DETECTION
DIMENSIONS
LEVELS
MEASURING INSTRUMENTS
SEISMIC EVENTS
580201* - Geophysics- Seismology & Tectonics- (1980-1989)
450300 - Military Technology
Weaponry
& National Defense- Nuclear Explosion Detection