Data Sources

Sources of information

Crustal Model

The crustal model builds on a wide variety of information:

• Refraction surveys: providing velocity models (mostly P wavespeed) and discontinuity mapping
• Receiver-function studies: S velocity profiles with some P information and definition of discontinuities derived from the wavetrain following the P wave arrivals from distant earthquakes.
• Reflection surveys: definition of base of sediments and crustal discontinuities, time information can be calibrated through refraction or receiver-function studies
• Crustal tomography: using passive seismic studies, in particular the exploitation of ambient noise via cross-correlation between stations to extract high-frequency surface wave signals
• Gravity interpretation: based on reflection models as a guide to density
• The database of sediment thickness across Australia (OZ SEEBASE)

Some supplementary information was drawn from global models
     + The global sediment map at 1 degree resolution (Laske & Masters)
     + The global crustal model CRUST2.0 (Bassin et al., 2000) with 2 degree resolution (2°x2°).

Mantle Model

The mantle model builds on existing tomographic studies of the Australian region:

• Surface wave tomography: extraction of S wave velocity models from the large amplitude surface waves generated by regional earthquakes recorded at Australian and regional stations. Several different styles have been used and good results are available to 300 km depth
• Full waveform tomography: works with longer wavelengths and consequently lower resolution but provides information to 700 km for S wavespeed.
• P and S wave delay time tomography: valuable for providing definition of structure to greater depth and also for calibration of how to convert an S wavespeed model into a P wavespeed model

In addition the model has been tested against a compilation of P and S wave travel times for well characterised events. The global model S40RTS is used as a background to allow modelling of a distant earthquake by accounting for structure outside the Australian Plate.

Detail on the construction process and the particular data employed will be found in the various papers.

Last updated 14 August 2018