Article,
A model for the shape of the fourier amplitude spectrum of acceleration at high frequencies
Bulletin of the Seismological Society of America, 74 (5): 1969--1993 (Oct 1, 1984)
Abstract
At high frequencies f the spectrum of S-wave accelerations is characterized
by a trend of exponential decay, e-pikf. In our study, the spectral
decay parameter k shows little variation at a single station for
multiple earthquakes at the same distances, but it increases gradually
as the epicentral distance increases. For multiple recordings of
the San Fernando earthquake, k increases slowly with distance, and
k is systematically smaller for sites on rock than for sites on alluvium.
Under the assumption that the Fourier spectrum of acceleration at
the source is constant above the corner frequency (an omega-2 source
model), the exponential decay is consistent with an attenuation model
in which Q increases rapidly with depth in the shallow crustal layers.
