Accession Number:

ADA169965

Title:

Teleseismic Waveform Modeling Incorporating the Effects of Known Three-Dimensional Structure Beneath the Nevada Test Site.

Descriptive Note:

Technical rept. no. 2, 1 Aug 85-31 Jan 86,

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE EARTH RESOURCES LAB

Personal Author(s):

Report Date:

1986-04-14

Pagination or Media Count:

42.0

Abstract:

Calculations were performed in 3-D models of the upper 75 - 100 km. of the crust ad mantle beneath the NORSAR array, a model for a region in the northerm California Zandt, 1981, and a model generated by random perturbations to a 1-D velocity structure. In both the NORSAR and Zandt models, azimuthal variations in travel time were found to be on the order of a factor of 2 and variations in teleseismic amplitude were found to be on the order of several 0.1s of a second. These models has a maximum of 4 to 8 velocity fluctuation over scale lengths of 10 to 100 km. The results obtained with a random model show that a model having a maximum velocity fluctuation as small as 0.8 percent is capable of producing caustics and multipaths at teleseismic range. The production of multipaths strongly depends on the anisotropy of the distribution of scale lengths, i.e., the ratio of characteristic vertical and horizontal scale length. The multipaths of the random model, however, occurred over too small an area and were too closely spaced in arrival time to be resolve with standard seismograph systems operating in the 0.01 to 4 Hz. band.

Subject Categories:

  • Geology, Geochemistry and Mineralogy
  • Seismology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE