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Some empirical relations for attenuation of ground-motion spectral amplitudes in Southwestern Western Australia

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Created 14/01/2025

Updated 14/01/2025

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A dataset comprising some 260 seismograph and accelerograph records from 67 events of the Burakin 2001-02 earthquake sequence was compiled to develop regional ground-motion models for southwestern Western Australia. Events range in size from moment magnitude 2.3 - M - 4.6. The decay of spectral amplitudes can be approximated by a geometrical spreading coefficient of R-1.05 within 80 km of the source. The associated model for the regional seismic quality factor can be expressed as Q(f) = 290f1.09. These attenuation parameters are subsequently used to evaluate average source parameters for the 67 earthquakes. For the observed magnitude range, data demonstrates a seismic moment (M0) - local magnitude (ML) relation following: log M0 = 1.14 ML + 10.45, where M0 is in N-m. Average corner frequencies for these events do not vary significantly with M0 particularly for events M > 3.0, chiefly ranging between 2-3 Hz. This gives rise to anomalously low stress drops for lower magnitudes (M < 4.0) that increase at larger magnitudes.

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Title Some empirical relations for attenuation of ground-motion spectral amplitudes in Southwestern Western Australia
Language eng
Licence Not Specified
Landing Page https://devweb.dga.links.com.au/data/dataset/1d9c1d99-5e46-4351-b92c-acaf76ff89df
Contact Point
Geoscience Australia
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
Data Portal Data.gov.au