SEPARATION OF SCATTERING ATTENUATION AND INTRINSIC ABSORPTION IN JAPAN USING THE MULTIPLE LAPSE TIME WINDOW ANALYSIS OF FULL SEISMOGRAM ENVELOPE

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.