Basic Research in Nuclear Test Monitoring: Seismic Wave Scattering from Irregular Interfaces.

• Main Authors: Schultz, Craig A., Dainty, Anton M., Toksoez, M. N.
• Other Authors: MASSACHUSETTS INST OF TECH CAMBRIDGE
• Format: Text
• Language: English
• Published: 1994
• Subjects: Seismology; Nuclear Weapons; *NUCLEAR EXPLOSION TESTING; *SEISMIC WAVES; *PRIMARY WAVES(SEISMIC WAVES); *SEISMIC ARRAYS; INTERFACES; ACOUSTIC WAVES; SEISMIC DETECTION; BACKSCATTERING; EARTH CRUST; ANGLE OF INCIDENCE; SEISMIC VELOCITY; MOHOROVICIC DISCONTINUITY; SEISMOGRAPHS; NORESS(NORWEGIAN EXPERIMENTAL SMALL SUBARRAY); ARCESS(ARCTIC EXPERIMENTAL SMALL SUBARRAY); FINESA(FINNISH EXPERIMENTAL SEISMIC ARRAY); NYNEX ARRAY; PE61102F; WUAFOSR2309AS; Arctic
• Online Access: http://www.dtic.mil/docs/citations/ADA290174; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA290174

We report on two investigations of seismic wave scattering from irregular interfaces. The first is a laboratory study of the scattering of ultrasonic waves incident on a glass surface etched to produce a highly irregular 3-D interface. We find that 2-D numerical simulations predict the 3-D experimental results well at small incident angles. Both numerical and experimental results strongly support the presence of enhanced backscattering. The second study is an analysis of regional P wave coda observed from events recorded at the Scandinavian NORESS, FINESA, and ARCESS arrays and the New England NYNEX array. The F-K spectra of the P coda are dominated by on-azimuth energy with apparent velocities between Pn (or faster) and Lg. Following this analysis, reflection coefficients calculated with a boundary integral scheme are used to study the role irregular interfaces play in the creation of regional P coda. We find that observed crustal scattering in these regions is strikingly consistent with P-P and P-SV scattering from the 2-D irregular Moho and even more consistent with scattering from a 2-D irregular near surface interface. (MM)