Experimental Studies of Stochastic Geologic Influences On Near-Source Ground Motions
- Steven R. Taylor,
- Howard J. Patton and
- Paul G. Richards
Published Online: 18 MAR 2013
Copyright 1991 by the American Geophysical Union.
Explosion Source Phenomenology
How to Cite
Reinke, R. E. and Stump, B. W. (1991) Experimental Studies of Stochastic Geologic Influences On Near-Source Ground Motions, in Explosion Source Phenomenology (eds S. R. Taylor, H. J. Patton and P. G. Richards), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM065p0063
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875900315
Online ISBN: 9781118663820
- Underground nuclear explosions—Detection—Congresses;
Analysis of accelerograms recorded at the same ranges but multiple azimuths from small-scale (5–100 lbs) high explosive experiments revealed wide (as large as 20 dB in the amplitude modulus of the Fourier transform) variations in response for frequencies higher than 30–40 Hz. Additional experiments were performed which ruled out source asymmetry or instrumental irregularity as the cause of these variations. The observations suggest that scattering by geologic inhomogeneity is responsible for the frequency-dependent spatial variability in ground motion. Modeling of the physical processes responsible for this variability requires a statistical description of the subsurface heterogeneity. One set of experiments was designed to accomplish this. Cone penetrometer testing was employed to directly probe the subsurface where a set of high explosive experiments was performed. High-resolution surface seismic surveys were performed at the site to characterize the deterministic and stochastic wave propagation effects. A statistical description of the subsurface is being developed from this data set and will be used in a simulation of wave propagation in random media. Although this paper deals specifically with travel paths a few tens of meters in length and random media scale lengths on the order of a fraction of a meter to a few meters in length, other examples in the literature suggest that random geologic variability exerts a significant influence on the complete spectrum of wave propagation from the near-field to teleseismic ranges and frequencies.