M. Hoshiba, SEPARATION OF SCATTERING ATTENUATION AND INTRINSIC ABSORPTION IN JAPAN USING THE MULTIPLE LAPSE TIME WINDOW ANALYSIS OF FULL SEISMOGRAM ENVELOPE, J GEO R-SOL, 98(B9), 1993, pp. 15809-15824
Two seismic wave attenuation factors, scattering attenuation (Q(s)-1)
and intrinsic absorption (Q(i)-1), can be determined from estimates of
two parameters, the reciprocal of extinction length L(e)-1=(Q(s)-1+Q(
i)-1).omega/v and seismic albedo B0=Q(s)-1/(Q(s)-1+Q(i)-1), where omeg
a and v are angular frequency and seismic wave velocity, respectively.
These parameters are measured using the multiple lapse time window an
alysis method over frequency bands of 1-2, 2-4, and 4-8 Hz from 16 sta
tions located throughout Japan. In the analysis, time-integrated seism
ic wave energy from earthquakes having hypocentral distances less than
120 km and focal depths less than 40 km are compared with simulations
of multiple isotropic scattering based on the assumption of spatial u
niformity of Q(s)-1 and Q(i)-1. The modified coda normalization method
is used to correct for sources and site effects, where the spatially
non uniform distribution of the coda wave energy is considered. The L(
e)-1 estimates do not have a distinct frequency dependence. but the B0
estimates do: 0.2-0.7 for 1-2 Hz and 0.1-0.3 for 4-8 Hz. The results
mean that Q(s)-1 is similar to Q(i)-1 for 1-2 Hz but is 3-5 times smal
ler for 4-8 Hz and that the frequency dependence of Q(s)-1 is larger t
han Q(i)-1. Analyses using different components of motion and differen
t window lengths give nearly the same results. Coda attenuation (Q(c)-
1) estimates based on the single scattering approximation are nearly e
qual to intrinsic absorption Q(i)-1 rather than to total attenuation (
Q(s)-1+Q(i)-1) for Japan.