@article{epos1357,
          volume = {97},
          number = {4},
           month = {August},
          author = {T. I. Allen and P. R. Cummins and T. Dhu and J. F. Schneider},
           title = {Attenuation of Ground-Motion Spectral Amplitudes in Southeastern Australia},
       publisher = {Seismological Society of America},
            year = {2007},
         journal = {Bulletin of the Seismological Society of America},
           pages = {1279--1292},
             url = {https://episodesplatform.eu/eprints/1357/},
        abstract = {A dataset comprising some 1200 weak- and strong-motion records from
84 earthquakes is compiled to develop a regional ground-motion model for south-
eastern Australia (SEA). Events were recorded from 1993 to 2004 and range in size
from moment magnitude 2.0 {\ensuremath{<}}= M {\ensuremath{<}}= 4.7. The decay of vertical-component Fourier
spectral amplitudes is modeled by trilinear geometrical spreading. The decay of low-
frequency spectral amplitudes can be approximated by the coef?cient of R{\^{ }}(-1.3)
(where
R is hypocentral distance) within 90 km of the seismic source. From approximately
90 to 160 km, we observe a transition zone in which the seismic coda are affected
by postcritical re?ections from midcrustal and Moho discontinuities. In this hypo-
central distance range, geometrical spreading is approximately R{\^{ }}0.1. Beyond
160 km, low-frequency seismic energy attenuates rapidly with source?receiver distance, having a geometrical spreading coef?cient of R{\^{ }}(-1.6). The associated regional
seismic-quality factor can be expressed by the polynomial: log Q(f) = 3.66 - 1.44
log f + 0.768 (log f){\^{ }}2 + 0.058 (log f){\^{ }}3
for frequencies 0.78 {\ensuremath{<}}= f {\ensuremath{<}}= 19.9 Hz.
Fourier spectral amplitudes, corrected for geometrical spreading and anelastic attenuation, are regressed with M to obtain quadratic source scaling coef?cients. Modeled vertical-component displacement spectra ?t the observed data well. Amplitude
residuals are, on average, relatively small and do not vary with hypocentral distance.
Predicted source spectra (i.e., at R = 1 km) are consistent with eastern North American (ENA) models at low frequencies (f less than approximately 2 Hz) indicating
that moment magnitudes calculated for SEA earthquakes are consistent with moment
magnitude scales used in ENA over the observed magnitude range.
The models presented represent the ?rst spectral ground-motion prediction equations developed for the southeastern Australian region. This work provides a useful
framework for the development of regional ground-motion relations for earthquake
hazard and risk assessment in SEA.}
}