The 2012 Australia National Seismic Hazard Model

The 2012 Australia national seismic hazard model is described in the reports by Burbidge (2012) and Leonard et al. (2013). We present here a description of the OpenQuake-engine implementation of the model.

The seismic source model consists of three different layers of seismic sources: continental-scale background zones, regional-scale area sources, and small-scale (hot spots) zones describing localized seismic sequences. Background zones (which contain holes where regional scale sources are defined) are implemented as gridded seismicity models, which are collections of NRML pointSource objects. Regional-scale sources and hot-spot zones are instead modeled as NRML areaSource objects.

The whole source model is divided into the following sub-models:

  • Background and regional cratonic model
  • Background and regional not-cratonic model
  • Hot spots cratonic model
  • Hot spots non-cratonic model

The map below depicts the annual occurrence rate per source (between minimum and maximum magnitudes) for the different source models included in the hazard model. Click the show map layers icon to view different source models and base layer maps.

operating instructions

Various functions are available as part of the map.

mouse/touch operation
  • moving by grabbing the map with a mouse-click you can move the map around
  • overview map using the + button in the bottom right of the map you can expand an overview map
  • zooming in and out using the + and - buttons in the top left of the map you can obtain more or less detail in the map
  • switching themes or maps clicking on the ≡ icon on the right-hand side of the map you can view and select available maps and themes
  • retrieving information the map may contain elements that contain more information, by clicking these a popup will show this information
  • fullscreen display using the ✈ button the map can be maximized to fullscreen display, use the ✕ button to return to page display.
keyboard operation

Keyboard operation becomes available after activating the map using the tab key (the map will show a focus indicator ring).

  • moving using the arrow keys you can move the map
  • overview map using the + button in the bottom right of the map you can expand an overview map
  • zooming in and out using the + and - buttons in the top left of the map or by using the + and - keys you can obtain more or less detail in the map
  • switching themes or maps clicking on the ≡ icon on the right-hand side of the map you can view and select available maps and themes
  • retrieving information the map may contain elements that contain more information, using the i key you can activate a cursor that may be moved using the arrow keys, pressing the enter will execute an information retrieval. press the i or the escape key to return to navigation mode
  • fullscreen display using the ✈ button the map can be maximized to fullscreen display, use the ✕ button to return to page display.

It's possible that some of the functions or buttons describe above have been disabled by the page author or the administrator

 

Total occurrence rate
(number of events / year)
  • < 1e-6
  • 1e-6 - 1e-5
  • 1e-5 - 1e-4
  • 1e-4 - 1e-3
  • 1e-3 - 1e-2
  • 1e-2 - 1e-1
  • 1e-1 - 1
  • 1 - 10
  • >= 10









The ground motion model distinguishes between two main tectonic regions:

  • Cratonic
  • Non-cratonic

For each tectonic region, the model considers multiple ground motion prediction equations organized in a logic tree structure.

Reference site condition

The reference site condition for the 2012 Australia national seismic hazard map is defined as generic rock assumed to have a Vs30 = 760 m/s. The Atkinson and Boore 2006 and the Chiou and Youngs 2008 GMPEs accept Vs30 as a prediction variable. The Allen 2012 and Somerville et. al. 2009 models are instead calibrated for Vs30 equal to 820 m/s and 865 m/s, respectively. For calculation purposes, the default site conditions are assumed consistent with the generic rock conditions.

Hazard maps

The figures below represent hazard maps for peak ground acceleration, for 10% and 2% probability of exceedance in 50 years, as computed by the OpenQuake-engine. Hazard maps are computed following the methodology described by Burbidge (2012). Separate hazard calculations are done for the background and regional model and for the hot spots model. Where the hot spots model predicts higher hazard level than the background and regional model, the mean of the two is taken.

Comparison against Geoscience Australia (GA) hazard results

The figure below shows the comparison between hazard map values for two return periods (RP) of 500 and 2500 years for the capital cities of Australia. GA reference values were taken from table 2, page 36 in Leonard et. al. (2013).

  • Burbidge, D. R. (2012). The 2012 Australian Earthquake Hazard Map. Record 2012/071. Geoscience Australia. Canberra.Download .pdf
  • Leonard, M., Burbidge, D. and Edwards, M. (2013). Atlas of seismic hazard maps of Australia: seismic hazard maps, hazard curves and hazard spectra. Record 2013/41. Geoscience Australia: Canberra. Download .pdf
  • Leonard, M. (2010). Earthquake Fault Scaling: Self-Consistent Relating of Rupture Length, Width, Average Displacement, and Moment Release. Bulletin of the Seismological Society of America, 100(5A), 1971–1988. doi:10.1785/0120090189. Journal website
  • McPherson, A.A. & Hall, L.S., 2007. Development of the Australian National Regolith Site Classification Map. 1 ed. Record 2007/007. Geoscience Australia, Canberra. Link

This table summarises the main characteristics of the original implementation of this model

1 Datasets availability
1.1 Earthquake catalogue Not available. The procedure used to create the catalogue is well described in Chapter 2 of Burbidge (2012)
1.2 Geological database A database of faults is available but this hazard model does not include fault sources.
1.3 Strong-motion database Not available. In Chapter 5 of Burbidge (2012) there is a comprehensive comparison between candidate GMPEs and recorded data.
1.4 Site characterization database We assume the Regolith map of McPherson et al. (2007) has been used
Notes
2 Methodology for model development
2.1 Scientific participation (SSHAC levels) and review process Level 2
2.2 Documentation describing model preparation See Burbidge (2012)
2.3 Codes used for model preparation Not available
Notes
3 PSHA input model
3.1 Seismic Source Model
3.1.1 Area sources Included
3.1.2 Grid sources Not included
3.1.3 Crustal faults Not included
3.1.4 Subduction faults Not included
3.1.5 Non-parametric ruptures Not included
3.1.6 Magnitude-area scaling relationships Leonard (2010)
3.2 Ground Motion Model
3.2.0 Tectonic regionalisation The model defines two tectonic provinces: cratonic and non-cratonic.
3.2.1 Models for active shallow seismicity Not explicity included
3.2.2 Models for subduction interface Not included
3.2.3 Models for subduction intraslab Not included
3.2.4 Models for stable continental regions Included
3.2.5 Models for deep non-subduction sources Not included
3.2.6 Models for volcanic areas Not included
3.3 Site Response Model
3.3.1 Based on GMPEs Yes, hazard is computed for a reference soil condition corresponding to NEHRP B/C boundary (Vs30=760 m/s)
3.3.2 Based on site-response analysis No
3.4 Epistemic uncertainties
3.4.1 Seismic Source Model Not explicitly included (Mmax determined by weighted average of three studies).
3.4.2 Ground Motion Model Included using a logic tree (see the ground motion model section)
3.4.3 Site Response Model Not included
Notes
4 Hazard Input Description
4.1 Hazard input document Not avaliable
4.2 Input files Not available
Notes
5 Calculation
5.1 Software GA’s Earthquake Risk Model (EQRM)
Notes The EQRM sofware can be downloaded here
5.2 Results
5.2.1 Hazard curves Available for the major cities
5.2.2 Hazard maps Available
5.2.3 Uniform hazard spectra Available for the major cities
5.2.4 Disaggregation Not available
5.2.5 Stochastic event sets The methodology adopted for the calculation of hazard uses stochastic event sets but these are not presented as results of the analysis
5.2.6 Ground motion fields As per “stochastic event sets”
Notes

The OpenQuake-engine input model (NRML format) can be downloaded at the link provided below - Please read the license and disclaimer attached to the model.

N.B. This is a model adapted by GEM Hazard Team to the OpenQuake-engine from the original model developed by Geoscience Australia. This explains minor differences you might encounter between the results presented in the OpenQuake platform and those disseminated by the original Organisation.

Download

  • australia_2012_intro.txt
  • Last modified: 2016/10/07 10:14
  • by Armando Scarpati