Earthquake characteristics and earthquake-explosion discrimination. Semi-annual technical report No. 6, 1 May-31 Oct 77
Two major advances have been made in the research on synthesis of long-period S waves at distances less than 40 degrees: the incorporation of inelastic attenuation and the development of a code to include a representation of the source function. The large effects on the waveforms of rapid variations of velocity in the upper mantle can be calculated and separated from the effects of anelasticity. Examples of synthetic seismograms are included to illustrate the effects of attenuation on the displacement waveforms, as well as the effects of the response of a typical long-period seismograph system. The application of Green's Function techniques to elastodynamics has led to methods for treating a variety of problems in wave propagation and earthquake source representations. The complete theory is given. There is evidence that specific anelastic attenuation, expressed as Q, is frequency dependent. Q models of the Earth based on free oscillations, surface waves and body waves show that in the broad frequency band covered by the input data, Q increases with frequency. The important conclusions is that the P and S attenuation data can only be reconciled by including a bulk loss mechanism, in addition to a shear loss mechanism. Although the results are not unique, this suggests that the bulk loss mechanism is operative in the upper mantle, perhaps within the asthenosphere.
- Research Organization:
- Cooperative Inst. for Research in Environmental Science, Boulder, CO (USA)
- OSTI ID:
- 5900777
- Report Number(s):
- AD-A-129772/0
- Country of Publication:
- United States
- Language:
- English
Similar Records
Seismic wave propagation and earthquake characteristics in Asia. Semiannual technical report No. 2, 1 May--31 Oct 1975
Earthquake characteristics and earthquake-explosion discrimination. Semi-annual technical report no. 3, 1 Nov 75-30 Apr 76
Related Subjects
450300* -- Military Technology
Weaponry
& National Defense-- Nuclear Explosion Detection
DETECTION
DIFFERENTIAL EQUATIONS
EARTH MANTLE
EARTHQUAKES
EQUATIONS
EXPLOSIONS
MEASURING INSTRUMENTS
NUCLEAR EXPLOSION DETECTION
PARTIAL DIFFERENTIAL EQUATIONS
SEISMIC ARRAYS
SEISMIC DETECTION
SEISMIC DETECTORS
SEISMIC EVENTS
SEISMIC S WAVES
SEISMIC WAVES
SEISMOGRAPHS
UNDERGROUND EXPLOSIONS
WAVE EQUATIONS
WAVE PROPAGATION