The 2018 National Seismic Hazard Assessment for Australia

Transcription

1 Record 2018/32 ecat The 2018 National Seismic Hazard Assessment for Australia Model input files T. Allen, J. Griffin, and D. Clark APPLYING GEOSCIENCE TO AUSTRALIA S MOST IMPORTANT CHALLENGES

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3 The 2018 National Seismic Hazard Assessment for Australia Model Input Files GEOSCIENCE AUSTRALIA RECORD 2018/32 T. Allen, J. Griffin and D. Clark

4 Department of Industry, Innovation and Science Minister for Resources and Northern Australia: Senator the Hon Matthew Canavan Secretary: Dr Heather Smith PSM Geoscience Australia Chief Executive Officer: Dr James Johnson This paper is published with the permission of the CEO, Geoscience Australia Commonwealth of Australia (Geoscience Australia) 2018 With the exception of the Commonwealth Coat of Arms and where otherwise noted, this product is provided under a Creative Commons Attribution 4.0 International Licence. ( Geoscience Australia has tried to make the information in this product as accurate as possible. However, it does not guarantee that the information is totally accurate or complete. Therefore, you should not solely rely on this information when making a commercial decision. Geoscience Australia is committed to providing web accessible content wherever possible. If you are having difficulties with accessing this document please clientservices@ga.gov.au. ISSN X (PDF) ISBN (PDF) ecat Bibliographic reference: Allen, T., Griffin, J. and Clark, D The 2018 National Seismic Hazard Assessment for Australia: model input files. Record 2018/32. Geoscience Australia, Canberra.

5 Contents 1 Introduction Fault-Source Model Fault Model Shapefile OpenQuake-Engine Input File Area Source Models Area Source Shapefiles OpenQuake-engine Input Files Smoothed Seismicity Models Regional Seismotectonic Models Plate Margin Source Model Final NSHA18 Input Files Source Model Logic Tree Ground Motion Logic Tree Job Configuration Files Site List Files Additional Data Files Model Summary Files Source Zone Statistics Source Zone Earthquake Lists Summary Acknowledgements References Appendix A Example NSHA18 Job Configuration File Insert document title here iii

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7 1 Introduction This Geoscience Australia Record contains technical data and input files that, when used with the Global Earthquake Model s (GEM s) OpenQuake-engine probabilistic seismic hazard analysis software (Pagani et al., 2014), will enable end users to explore and reproduce the 2018 National Seismic Hazard Assessment (NSHA18) of Australia (Allen et al., 2018a). This report describes the NSHA18 input data only and does not discuss the scientific rationale behind the model development. These details are provided in Allen et al. (2018a) and references therein. A range of products are provided in the accompanying data package. These include: A shapefile of the simplified national fault-source model and its attributes (Clark et al., 2016); Area-source-model shapefiles with zone-specific attribute data (Section 3.1); Area-source-model summary files (Section 8.1) showing : o o o Mapped b-values; Maps of area-normalised earthquake rates; Comma separated value (csv) files of shapefile attribute data. Within an area-source model, zone-specific information, including: o Observed and forecast earthquake magnitude-frequency information (Section 8.2); o o Lists of earthquakes that both passed and failed magnitude completeness tests (Section 8.3); Earthquake occurrence parameterisation for the offshore plate margins seismic sources (see Sections 6 and 8.2; Davies and Griffin, 2018; Griffin and Davies, 2018). OpenQuake-engine source-model files for: o Regional and background area sources (Section 3.2); o Smoothed seismicity sources (Section 4); o Seismotectonic sources models that combine regional models and faults (Section 5); o Smoothed seismicity models incorporating the national fault source model. OpenQuake-engine logic tree files for (Section 7.1 and 7.2): o Seismic-source models (Section 7.1); o Ground-motion models (Section 7.2). Additional OpenQuake-engine inputs (Section 7.4), including: o o Site list for generating the NSHA18 hazard grid; Standards Australia s AS (Standards Australia, 2007) and other locality site locations in csv and shapefile format. The different data types are discussed briefly below. The accompanying data package directory structure follows the same structure and numbering as used in this document and is illustrated in Figure 1. For instructions on installing and running the OpenQuake-engine, readers are referred to Model Input Files 1

8 Pagani et al. (2018). The NSHA18 calculations were completed using the source-model files described in this Record using Version 3.1 of the OpenQuake-engine. Figure 1: Folder structure for the NSHA18 data inputs package. The Model Name is defined in Section 3 and Zone Name refers to the individual source zones within a source model. 2 The 2018 National Seismic Hazard Assessment

9 2 Fault-Source Model The NSHA18 has, for the first time, incorporated a national fault source model (NFSM) in the calculation of seismic hazard values for Australia (Clark et al., 2016). The model includes some 356 onshore faults and 23 offshore faults, which are modelled as simplified planes and are assigned a general dip and rake direction. Fault dips are obtained preferentially from seismic-reflection profiles, or are otherwise inferred from surface geology and geomorphology. Alternatively, fault dip is estimated using fault geometries from similar neotectonic settings as a proxy. The base of seismogenic rupture for the fault model is generally taken as the regional maximum seismogenic depth modelled in the distributed seismicity sources (see Section 3.1). Slip rates are calculated from: 1) displaced strata of known age; 2) estimated from surface expression combined with knowledge of landscape modification rates (e.g., erosion and/or deposition), and/or; 3) are estimated by proxy from similar neotectonic settings. In a small number of instances slip rate data are available from paleoseismic trenching investigations (e.g., Quigley et al., 2006; Clark et al., 2011; Clark et al., 2015). These data provide a snapshot of the last few events on the fault, and typically capture slip rates during an active period on the fault (SL_RT_ST; Table 1). Data from displaced strata or geomorphic surfaces of known age can provide fault slip estimates over longer time intervals, potentially spanning active and quiescent periods on the fault (i.e., long-term slip rates; SL_RT_LT; Table 1) (e.g., Sandiford, 2003; Gardner et al., 2009). The majority of features in the Australian Neotectonic Features Database are not associated with explicit fault displacement data. In these instances, the height of a scarp feature might be used as a proxy for vertical displacement, with guidance from better documented features within the same neotectonic domain as to how much expression is likely to be neotectonic (UP_RT_ST/UP_RT_LT; Table 1). An understanding of the landscape modification rates (i.e., erosion and deposition) is crucial to accurate estimates of long term slip rates for these features. A ±20% uncertainty is reasonable for slip-rate estimates. 2.1 Fault Model Shapefile The shapefile hosting simplified NFSM is available in the electronic data package accompanying this record. A description of the shapefile attribute fields is listed in Table OpenQuake-Engine Input File Data from the NFSM shapefile were converted to OpenQuake-engine Extensible Markup Language (xml) format. Whilst this file is not used independently in the NSHA18 hazard model, it has utility in being able to isolate the effects of the fault-source model. The earthquake magnitude-frequency distributions (MFDs) for fault sources were modelled as either Gutenberg Richter (1944), Youngs and Coppersmith (1985) characteristic earthquake, or maximum magnitude recurrence (i.e., single M max ruptures only, with approximately periodic recurrence). Each of the occurrence model types were implemented and weights, determined from the expert elicitation workshop (Griffin et al., 2018), were used to collapse the occurrence rates of earthquakes onto an incremental MFD by calculating the weighted mean rate for each magnitude bin of the distribution. Model Input Files 3

10 Table 1: Simplified Fault Source Model Attributes as derived from the Australian Neotectonic Feature Database. NFSM Field Name Length Dip dip_dir SL_RT_ST SL_RT_LT UP_RT_ST UP_RT_LT Comment Description Fault name Length of simplified fault (km) Fault dip (often assumed from analogue features) Direction of fault dip Short-term slip rate in m/million years (zero if unknown) Long-term slip rate in m/million years Short-term uplift rate in m/million years (zero if unknown) Long-term uplift rate in m/million years Comments field 4 The 2018 National Seismic Hazard Assessment

11 3 Area Source Models Two types of area source zones are modelled in the NSHA18: background and regional source models. Background area source models capture broad geographic areas and allow for large earthquakes to occur anywhere within these areas with equal probability. These are models that have 20 or fewer zones on a national scale. In contrast, regional area-source models assume that the spatial distribution of seismicity is non-uniform at the scale of background source zones. These source models typically have 30 or more zones. The background and regional area source models used in the NSHA18 are listed in Table 2, together with their associated weights (Allen et al., 2018a; Griffin et al., 2018). In this data package, the area source models are provided in two formats: 1) spatially enabled shapefiles with complete zone-specific parameterization within the shapefile attributes, and; 2) xml-formatted files as used with the OpenQuake-engine (Pagani et al., 2018). These file types are described in the sections below. Table 2: List of Geoscience Australia and third-party source models considered for use in the NSHA18 together with their assigned weights from the Expert Elicitation Workshop (Griffin et al., 2018). Model Name Model Type Inter-Class Weight Intra-Class Weight Reference AUS Dimas et al. (2016) DIM-AUS Regional Dimas and Venkatesan (2016) NSHM Burbidge (2012) and Leonard et al. (2012) ARUP* Mote et al. (2017) Leonard Leonard (2008) Neotectonic Domains Background Clark et al. (2012) NSHM12 Background Burbidge (2012) and Leonard et al (2012) Sinadinovski & McCue Sinadinovski and McCue (2016) Cuthbertson Cuthbertson (2016) Adaptive Smoothing Smoothed Griffin et al. (2016) Fixed Kernel Smoothing Seismicity Griffin et al. (2016) Risk Frontiers Hall et al. (2007) AUS6 with NFSM Dimas et al. (2016) DIM-AUS with NFSM Seismotectonic Dimas and Venkatesan (2016) NSHM12 with NFSM Griffin et al. (2016) and Clark et al. (2016) Cuthbertson Cuthbertson (2016) 2018 update Adaptive Smoothing Smoothed Griffin et al. (2016) Seismicity with Fixed Kernel Smoothing NFSM Griffin et al. (2016) Risk Frontiers Hall et al. (2007) 2018 update * The Arup source model has two branches comprising two equally weighted alternatives (Mote et al., 2017). In the NSHA18, earthquake recurrence for each earthquake source is described in terms of an asymptotically-truncated Gutenberg-Richter (1944) magnitude-frequency distribution (MFD) following: Model Input Files 5

12 NN(mm) = NN 0 ee ββββ 1 ee ββ(mm mmmmmm mm) (1) where N is the cumulative number of earthquakes greater than magnitude m, M max is the maximum magnitude asymptote of the MFD, N0 is equivalent to N(m=0) and β is a constant related to the Gutenberg and Richter (1944) b-value, where β = b ln(10). Here, we assume m is equivalent to moment magnitude M W. 3.1 Area Source Shapefiles All area-source models were converted from their original format to Environmental Systems Research Institute (ESRI) shapefile format (ESRI, 1998). They were subsequently all processed in the following uniform manner: 1. Area source zones were parsed and converted to a consistent shapefile format that preserved the original source boundaries provided by the model authors; 2. Each source model was adjusted to: 2.1. append the northern plate margin source model, and; 2.2. add a 500 km buffer from the Australian coastline (excluding offshore territories); 3. The area of the original and adjusted source zones were calculated to determine an earthquake rate adjustment factor; 4. Based on the centroid of individual source zones within a source model relative to the Neotectonic Domains source model (Clark et al., 2012), source models are systematically assigned with: 4.1. Tectonic region type (e.g., cratonic, non-cratonic, extended); 4.2. Maximum magnitude (M max) distribution with appropriate weights from the expert elicitation workshop (Griffin et al., 2018); 4.3. Preferred hypocentral depth and corresponding probability density function including the upper and lower seismogenic depths (Table 3); 4.4. Preferred fault nodal plane and corresponding probability density function based on the maximum horizontal stress vectors, S Hmax (Rajabi et al., 2017); 5. Based on centroid of individual source zones within a source model relative to the magnitude of completeness zones (Allen et al., 2018b), source models are systematically assigned with a multi-corner (M C) model; 6. For all background area source models, b-values for combined sources of similar tectonic region type were calculated using the NSHA18-Cat (Allen et al., 2018b). Zone-specific activity rates, N0, were then calculated using the fixed region-type b-values. The uncertainties in both the N0 and b-values are also assigned at this time; 7. For all regional area source models, b-values were assigned using the b-values calculated for the Neotectonic Domains model (Clark et al., 2012) for corresponding target tectonic region types. The maximum magnitude, M max, of each area source zone is assigned based on the tectonic region type. In calculating the Gutenberg-Richter magnitude-frequency statistics for each source zone, the M max logic tree was assigned via a lookup table as shown in Table 4. The M max values for the plate 6 The 2018 National Seismic Hazard Assessment

13 margin source model (see Section 6) were adopted from their respective original source models (Ghasemi et al., 2016; Davies et al., 2017; Irsyam et al., 2017). The area source model shapefiles were developed for each of the background and regional area source models listed in Table 2. A description of the shapefile attributes is provided in Table 5 and they are available in the electronic data package accompanying this record. See Allen et al. (2018a) for further details on the source model development. Table 3: Hypocentral depths (in km) and associated weights for each tectonic region type. Tectonic Region Type Depth 1 (Weight 1) Depth 2 (Weight 2) Depth 3 (Weight 3) Cratonic 2.5 (0.25) 5.0 (0.5) 10 (0.25) Non-Cratonic 5.0 (0.25) 10.0 (0.5) 15 (0.25) Extended Crust 5.0 (0.25) 10.0 (0.5) 15 (0.25) Oceanic Crust 10 (1.0) Subduction Interface hm (1.0)* Shallow Active Crust 10 (1.0) * The preferred depths for intraslab area sources use the median of the upper and lower seismogenic depths (hm). Table 4: Maximum magnitude (Mmax) lookup table and weights assigned for the NSHA18 based on a zone s tectonic region type (Griffin et al., 2018). Tectonic Region Type Mmax Mmax Weight Cratonic Non-cratonic Extended Model Input Files 7

14 Table 5: Definition of area-source model shapefile attributes. Attribute Definition SRC_NAME CODE Name of source area Abbreviated area source name DOMAIN Neotectonic Domain class as defined by Clark et al. (2012) CLASS Modified Neotectonic Domains class (Clark et al., 2012) used to aggregate seismic sources for b-value calculation AREA Area of source zone in km 2 DEP_BEST Preferred depth of earthquakes in the source zone in km DEP_UPPER Lower depth of earthquakes in the source zone in km. No data = DEP_LOWER Upper depth of earthquakes in the source zone in km. No data = USD LSD OW_LSD MIN_MAG MIN_RMAG MMAX MMAX_WGTS Upper seismogenic depth of zone (in km) constraining hypocentre searches and fault pseudo-ruptures Lower seismogenic depth of zone (in km) constraining hypocentre searches and fault pseudo-ruptures Overwrites LSD to include historical earthquakes in zone statistics if hypocentres are not included in any other three-dimensional volume Minimum magnitude used in seismic hazard input model Minimum magnitude considered for the MFD regression Array of Mmax values considered for each source as determined from the expert elicitation workshop (Griffin et al., 2018) Array of weights corresponding to Mmax values as determined from the expert elicitation workshop (Griffin et al., 2018) N0_BEST N0_LOWER N0_UPPER RATE_ADJ_F BVAL_BEST BVAL_LOWER BVAL_UPPER BVAL_FIX BVAL_FIX_S Preferred number of earthquakes per year with magnitude greater than or equal to zero Number of earthquakes per year with magnitude greater than or equal to zero for the lower curve Number of earthquakes per year with magnitude greater than or equal to zero for the upper curve Rate adjustment factor to correct earthquake occurrence rates for revision of source zone boundaries to merge common plate margin (Griffin and Davies, 2018) and continental buffer zones (Allen et al., 2018a). The factor is the ratio of the modified-tooriginal zone areas Gutenberg-Richter b-value - best estimate Gutenberg-Richter b-value - lower curve (i.e. higher b-value) Gutenberg-Richter b-value - upper curve (i.e. lower b-value) Fixed b-value from the Neotectonic Domains source model (Clark et al., 2012) for the regional and the plate margin source models. Equals if a free calculation. Fixed b-value uncertainty (± 1 standard deviation) from the Neotectonic Domains source model (Clark et al., 2012) for regional and the plate margin source models. Equals if a free calculation. PREF_STK Predefined preferred rupture strike in degrees from north. No data = PREF_DIP Predefined preferred rupture dip in degrees. No data = PREF_RKE Predefined preferred rupture rake in degrees. No data = SHMAX Average maximum horizontal stress direction (degrees from north) 8 The 2018 National Seismic Hazard Assessment

15 Attribute SHMAX_SIG SCALING_REL ASP_RATIO TRT GMM_TRT YCOMP MCOMP CAT_YMAX CAT_FILE Definition Standard deviation of average maximum horizontal stress direction. A minimum value of 15 is assigned Magnitude-area rupture scaling relationship used for pseudo-ruptures Aspect ratio for pseudo-rupture length-width scaling Tectonic Region Type Simplified mapping of TRTs to a ground-motion logic tree Zone-specific magnitude completeness years corresponding to MCOMP Zone-specific completeness magnitudes corresponding to YCOMP Maximum year of catalogue (in decimal years) Catalogue file used for source zone MFD 3.2 OpenQuake-engine Input Files The OpenQuake-engine source-model files for area-source models were developed directly from the shapefiles summarised in Section 3.1. A script was written to use the shapefiles to export OpenQuake-engine xml source model inputs. Through this process, the plate margin fault model (Griffin and Davies, 2018) is also appended to each of the seismic source models. The script can generate the following model sets: 1) best: a single model that provides the best fitting MFD and preferred M max; 2) multimod: 15 independent xml files that explore the full epistemic uncertainty of the MFD using three b-value branches (labelled as bb, bu, bl for best, upper and lower b-value) and five M max branches (labelled as m1-m5), or; 3) collapsed: a single xml file that collapses the 15 MFD branches to a single incremental MFD. The latter option allows for the epistemic uncertainty of the MFD to be considered in the mean hazard calculation, while having the benefit of significantly improving the computational efficiency. For each of these options, a source model logic tree is also output. In implementing the multimod option, simplifications were made to the weights for M max, assigning consistent weights for each tectonic region type (i.e., assigned weights are 0.1, 0.2, 0.4, 0.2, 0.1 for m1-m5, respectively). If this simplification was not made for this Option 2, 375 end branches would be required to perfectly replicate the mean rates given in Option 3. This was not considered practical, particularly given the source-model logic trees from Options 2 and 3 produce nearly identical hazard results. The OpenQuake-engine seismic source files were developed for each of the background and regional area source models listed in Table 2. End users are referred to the OpenQuake-engine user manual for more information on the file formats (Pagani et al., 2018). These source models are available in the electronic data package accompanying this record. The collapsed-rate files are duplicated in the final_nsha18_input_files folder (see Section 7). For further details on the source model development, see Allen et al. (2018a). Model Input Files 9

16 4 Smoothed Seismicity Models Smoothed seismicity models provide spatially-varying earthquake occurrence rates that are derived by smoothing the observed rates of instrumental earthquake occurrence across a given smoothing kernel (e.g., Frankel, 1995; Helmstetter et al., 2007). An advantage of smoothed seismicity models is that they are purely data-driven and have less dependence on the interpretation of the model developer. OpenQuake-engine-compliant files for the smoothed seismicity models were implemented both with and without the addition of the fault-source model. In these xml-formatted files, the models are implemented assuming single point sources, each associated with incremental occurrence rates, and a rupture nodal plane geometry logic tree. The respective weights for the smoothed seismicity, both with and without the NFSM are provided in Table 2. For smoothed seismicity models that embed the NFSM, the model was integrated using a purely additive approach. These files are found in the final_nsha18_input_files folder and are referenced in Section The 2018 National Seismic Hazard Assessment

17 5 Regional Seismotectonic Models Seismotectonic models used in the NSHA18 are those that include shallow crustal faults for continental Australia. There are three seismotectonic models combining regional area sources with the national fault database (AUS6, DIM-AUS and NSHM12). Three methods for integrating fault source models with surrounding area sources were proposed and weighted during the expert elicitation workshops (Griffin et al. 2018). These were additive, moment balancing and geometrical filtering methods. The latter two approaches are intended to avoid doublecounting seismicity in the long-term hazard forecasts. Allen et al. (2018a) discusses the rationale and the technical details regarding the geometrical filtering approach. The weights for parameterising the fault integration into the seismotectonic source models were calibrated through the expert elicitation workshop (Griffin et al., 2018). The weights of the each of the seismotectonic source models are given in Table 2. These files are found in the final_nsha18_input_files folder and are referenced in Section 7. Model Input Files 11

18 6 Plate Margin Source Model Earthquakes to the north of Australia in the eastern Indonesia and Papua New Guinea (PNG) regions have the potential to generate significant ground shaking in northern Australia. This has particular significance for northern Australian communities and infrastructure projects, with several large earthquakes in the Banda Sea (approximately 400 km away) having caused ground shaking-related damage in Darwin over the historical era (Vanden Broek, 1980; Hearn and Webb, 1984; McCue, 2013). A common plate margin area seismic source model was adapted from other recent regional assessments of seismic hazard in PNG (Ghasemi et al., 2016) and Indonesia (Irsyam et al., 2017). These plate margin area sources were stitched to the boundary of each of the source models developed for continental Australia. The plate margin model extends to a distance of more than 800 km from the mainland Australian coastline. This distance is based on the ground-motion model integration distance for the offshore plate margin region recommended by the expert elicitation panel (Griffin et al., 2018). Earthquake MFDs for the shallow crustal plate margin and intraslab area-source zones are calculated using the International Seismological Centre (ISC)-GEM catalogue (Version 5; Storchak et al., 2013). The completeness magnitude considered for this catalogue in the region of interest was magnitude M W 5.75 (Allen et al., 2018b), for earthquakes occurring since Major subduction interface and crustal faults were augmented to the plate margin area source model. Parameterisation of these fault sources was enabled through the aforementioned regional seismic hazard assessments for PNG and Indonesia, in addition to fault-source models compiled through the global tsunami hazard assessment (Davies et al., 2017). Further discussion on the parameterisation of the plate margin source model is provided in Griffin and Davies (2018) and Allen et al. (2018a). OpenQuake-engine xml-formatted seismic source models that are stitched to all continental Australian models are extracted and provided independently in the downloadable data package. 12 The 2018 National Seismic Hazard Assessment

19 7 Final NSHA18 Input Files This section provides an overview of the final model input files and directory structure used to calculate the NSHA18. It discusses the source-model logic tree, and provides reference to the final source-model files. It also discusses the ground-motion-model logic tree, provides an example of the typical OpenQuake-engine job initiation file, and provides details on the site files used to calculate hazard values for specific localities, as well as the site list used for the hazard map grids. For more information on the format of the OpenQuake-engine input files, readers are referred to Pagani et al. (2018) 7.1 Source Model Logic Tree In total, the NSHA18 implements 19 independent seismic source models, with the Arup source model comprising two equally weighted alternatives (Mote et al., 2017). The weight assigned to each source model is defined in Table 2. The final source model logic tree used in the NSHA18 is illustrated in Figure 2. Reference to the final source-model files available in the final_nsha18_input_files folder is given in Table 6. The final weights provided in the OpenQuake-engine source model logic tree file are the product of the inter-model class weight and the intra-model class weight (see Table 2). 7.2 Ground Motion Logic Tree In the absence of dedicated ground-motion model (GMM) logic trees for all tectonic region types, a simplified mapping of tectonic region to three ground-motion model logic trees was used (Table 7). Mapping of the extended and oceanic crustal GMMs to non-cratonic GMMs was justified given that they are more likely to be representative of non-cratonic regions than of cratonic crust. The subduction/banda Sea logic tree represents a mélange of GMMs from different tectonic regions and includes models originally defined for subduction intraslab, shallow active crust and stable continental regions. The intent for including this mix of models from different tectonic environments is to capture the uncertainty in both the source and attenuation properties of these earthquakes. The weight assigned to each GMM in each tectonic region type is defined in Table 8. These weights are reflected in the OpenQuake-engine GMM logic tree file referenced in Table Job Configuration Files An example of the job configuration file that could be used to run the NSHA18 within the OpenQuakeengine (Version 3.1) is provided in Appendix A. These files define the area of interest for the hazard calculation, the parameterisation for the earthquake rupture forecasts, reference to the seismic source and GMM logic trees and the definition of the ground motion intensity measure types for which the seismic hazard forecasts are calculated. The file also specifies the output types required and destination paths. Model Input Files 13

20 Figure 2: Final seismic source model logic tree used in the NSHA18. Citations for individual seismic source models are provided in Table 2. Table 6: Final list of files in 7_final_nsha18_input_files folder. 14 The 2018 National Seismic Hazard Assessment

21 Model Input Files 15

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23 Table 7: Simplified mapping of tectonic region types to three ground-motion model logic trees. Tectonic Region Type Cratonic Non-cratonic Extended Oceanic Active Shallow Crust Subduction Interface Subduction Intraslab GMM Region Cratonic Non-cratonic Subduction Table 8: Final ground-motion model weights applied in the NSHA18, modified from the GMC expert elicitation workshop. Model Name* Allen2012 Tectonic Region Type Intra- Region Weight Reference Allen (2012) AtkinsonBoore Atkinson and Boore (2006) Non-cratonic, BooreEtAl2014 Extended, Boore et al. (2014) ChiouYoungs2008SWISS01 Oceanic and Edwards et al. (2016) Active Crust ChiouYoungs Chiou and Youngs (2014) SomervilleEtAl2009NonCratonic Somerville et al. (2009) Allen Allen (2012) AtkinsonBoore Atkinson and Boore (2006) AtkinsonBoore2006Modified Atkinson and Boore (2011) BooreEtAl2014 Cratonic Boore et al. (2014) ChiouYoungs Chiou and Youngs (2014) SomervilleEtAl2009YilgarnCraton Somerville et al. (2009) ZhaoEtAl2006AscSWISS Edwards et al. (2016) AbrahamsonEtAl2015SSlab Abrahamson et al. (2016) Allen Allen (2012) AtkinsonBoore Atkinson and Boore (2006) AtkinsonBoore2006Modified2011 Subduction Atkinson and Boore (2011) AtkinsonBoore2003SSlab Atkinson and Boore (2003) BooreEtAl Boore et al. (2014) SomervilleEtAl2009NonCratonic Somerville et al. (2009) Integration Distance 400 km 400 km 1000 km * Model name refers to the OpenQuake-engine ground-motion model oq-hazardlib class (Pagani et al., 2018). 7.4 Site List Files The NSHA18 has generated site-specific hazard values for localities within the AS and other key sites (Figure 3). Additionally, seismic hazard is calculated for a uniform grid spaced at 15-km intervals across the Australian continent between E and a latitude range between 7-47 S. The number of sites in oceanic regions is reduced by randomly sampling points outside of the Australian continent to help optimise the hazard computation, while still providing constraint to interpolate offshore hazard contours. In total, hazard outputs are calculated for more than 54,000 grid Model Input Files 17

24 points over the Australian territory and surrounding areas (Figure 4). Both the AS locality site list and gridded sites are provided in the electronic data package (Table 6). Figure 3: Spatial distribution of tabulated settlements indicated in the AS (Table 3.2 in Standards Australia, 2007), as well as additional sites of interest. 18 The 2018 National Seismic Hazard Assessment

25 Figure 4: Spatial distribution of sites used to generate gridded hazard maps for the NSHA18. Model Input Files 19

26 8 Additional Data Files The preceding discussion has largely focused on input source model and logic tree files developed to run the probabilistic NSHA18 within the OpenQuake-engine. However, a number of intermediary files were generated through the model testing and evaluation phases. This section describes several of these output datasets, particularly as they pertain to the area-source models. They are intended to provide more transparency on the data and methods used to define earthquake MFDs for each areasource model contributed to the NSHA18. The data package provides a folder for each source model in which the summary files and intermediary zone specific data are stored. 8.1 Model Summary Files The shapefiles described in Section 3.1 embed all of the source model parameters specific to any source zone. Whilst simple to view, the authors recognize that some end-users will prefer to view these attributes in common spreadsheet software. Consequently, the data embedded within the shapefiles have been exported to csv format. These files have a naming convention of <Model>_SSM_Summary.csv, where Model is the model s name as defined in Table 2. The quality of the MFD fit to catalogue data for any given source zone is important to provide confidence and reassurance in the model s ability to forecast the future rates of large-magnitude earthquakes. The rates of these large earthquakes are sensitive to the estimate of the b-value. Whilst this information, together with the uncertainties in the earthquake rates, is provided in the model summary csv files, it is also informative to see these data mapped. Figure 5 shows an example of one of these maps for one of the background seismic source models. For the background source models, earthquake recurrence statistics are combined for pre-defined source zone classes, largely based upon the Neotectonic Domains (Clark et al., 2012). A single b-value for each zone class is then calculated. In addition to the maps of b-values, the annualized recurrence rates for earthquakes with a given moment magnitude are calculated for each source zone, and then normalized to an area of 10,000 km 2. Annualized earthquake rate maps are generated for each area source model for M W 5.0, 6.0 and 7.0 earthquakes, respectively. An example of an earthquake rate map is shown in Figure 6. The combined number of area sources, for Geoscience Australia and third-party contributed source models, numbered almost 340. For each of these source zones, a visual inspection of the MFD was generated. These files comprise the MFD fit to the earthquake epicentres enveloped by the zone, plots showing the magnitude completeness information, a plot showing the cumulative number of earthquakes M W 3.5 within the zone since the year 1900, a histogram of earthquake hypocentral depths, and a small map providing the geospatial reference for the zone. An example of these plots is provided in Figure 7. All of these maps and MFD fits are merged into a single pdf file with the file naming convention of <Model>_MFD.MERGE.pdf. 20 The 2018 National Seismic Hazard Assessment

27 Figure 5: Example map of the Gutenberg-Richter b-value as calculated for the Arup area-source model (Mote et al., 2017). Model Input Files 21

28 Figure 6: Annualised rate of MW 6.0 earthquakes for the Arup area-source model (Mote et al., 2017) normalised for an area of 10,000 km 2. Figure 7: Example Gutenberg and Richter (1944) MFD calculation for the Flinders and Mt Lofty Ranges zone for the Arup source model showing: earthquakes that pass (red) and don t pass (blue) the catalogue completeness model (top left) for use in the MFD calculations; cumulative count of earthquakes with Mw 3.5 (bottom left); fitted Gutenberg-Richter MFDs including b-value uncertainty (centre); and hypocentral depth distribution (top right) and spatial distribution (bottom right) of the catalogue. 22 The 2018 National Seismic Hazard Assessment

29 Model Input Files 23

30 8.2 Source Zone Statistics In addition to the source model summary files discussed above, the MFD statistics for each source zone of each area source model are also provided. These files summarise the observed and fitted Gutenberg-Richter MFD statistics for each source zone, and also give an area-normalized estimate of the earthquake rates so that source zones with different areas can be more meaningfully compared. A description of these files is provided in Table 9. These files are provided in the source model-specific directory structure following: <Model>/<Zone Code> Table 9: Description of the observed and fitted Gutenberg-Richter MFD statistics for each source zone. Abbreviation MAG N_OBS N_CUM BIN_RTE CUM_RTE MFD_FIT Definition List of magnitude bins from the minimum magnitude considered for fitting the MFD. The listed magnitude represents the lower bin edge with a width of 0.1 magnitude unit Number of earthquakes within magnitude bin width within the zone Cumulative number of earthquakes with magnitudes within and less than the given bin The zone-specific annual earthquake rate within the magnitude bin. This is the number of observations divided by the completeness period for that magnitude bin Rate Cumulative number of earthquakes within and less than the given bin The idealized Gutenberg-Richter MFD fitted to the observed data using the Weichert (1980) algorithm MFD_FIT_AREA_NORM The fitted Gutenberg-Richter MFD normalized to an area of 10,000 km 2 24 The 2018 National Seismic Hazard Assessment

31 8.3 Source Zone Earthquake Lists Also provided with the zone-specific information are lists of earthquakes that have both passed and failed magnitude completeness tests (Allen et al., 2018b). As with the source zone statistics files, this information is found in the following directory structure: <Model>/<Zone Code>. The files with earthquakes passing completeness testing are appended with _passed.dat and the file of events failing completeness is appended with _failed.dat. Each line of these respective files uses the following format: MW CAN The data attributes corresponding to the specified columns in the data file are described in Table 10. Table 10: Format of source zone-specific lists of earthquakes that have either passed or failed magnitude completeness testing. Character Column Description 1-4 Earthquake year 6-7 Earthquake month 9-10 Earthquake day Hour and minute of earthquake Longitude Latitude Hypocentral depth (zero if unknown) Preferred moment magnitude from NSHA18-Cat (Allen et al., 2018b) Preferred magnitude type (e.g. MW) 47-end Authority. See Allen et al. (2018b) for more details Model Input Files 25

32 9 Summary The 2018 National Seismic Hazard Assessment of Australia is one of the most complex, if not the most complex, seismic source models built to date for any national-scale seismic hazard assessment. The data package associated with this Geoscience Australia Record is provided to allow end users review and interrogate the NSHA18 model parameterisation. To run the full NSHA18 requires significant computational resources, and would likely be beyond the capability of users without access to high-end parallel computing infrastructure. However, elements of the NSHA18 can be run in isolation of the full model to enable exploration of model sensitivities. The release of these data ensures that the data used in the generation of the NSHA18 and its derivative products is transparent, discoverable and has well-defined provenance. This is essential to benchmark future seismic hazard studies in Australia. 26 The 2018 National Seismic Hazard Assessment

33 10 Acknowledgements Matt Gale is thanked for his GIS support in stitching the northern plate boundary seismic source model to all candidate area source models used in the NSHA18. Matt also provided support in developing shapefile metadata for the area source models. The Geoscience Australia NSHA18 team is particularly grateful to the Global Earthquake Model team, in particular Marco Pagani, Michele Simionato and Graeme Weatherill (now at GFZ) for their continued development, maintenance and support of the OpenQuake-engine. Hyeuk Ryu and Jonathan Bathgate are thanked for their internal reviews and thoughtful comments of this document. Most figures in the Record were generated using Python 2.7 matplotlib (matplotlib.org/) and the matplotlib basemap toolkit (matplotlib.org/basemap/). Model Input Files 27

34 11 References Abrahamson, N., N. Gregor, and K. Addo (2016). BC Hydro ground motion prediction equations for subduction earthquakes, Earthq. Spectra 32, 23-44, doi: /051712EQS188MR. Allen, T., J. Griffin, M. Leonard, D. Clark, and H. Ghasemi (2018a). The 2018 National Seismic Hazard Assessment for Australia: model overview, Geoscience Australia Record 2018/27, Canberra, doi: /Record Allen, T. I. (2012). Stochastic ground-motion prediction equations for southeastern Australian earthquakes using updated source and attenuation parameters, Geoscience Australia Record 2012/69, Canberra, pp 55. Allen, T. I., M. Leonard, H. Ghasemi, and G. Gibson (2018b). The 2018 National Seismic Hazard Assessment for Australia: earthquake epicentre catalogue, Geoscience Australia Record 2018/30, Canberra, doi: /Record Atkinson, G. M., and D. M. Boore (2003). Empirical ground-motion relations for subduction-zone earthquakes and their application to Cascadia and other regions, Bull. Seism. Soc. Am. 93, , doi: / Atkinson, G. M., and D. M. Boore (2006). Earthquake ground-motion prediction equations for eastern North America, Bull. Seism. Soc. Am. 96, , doi: / Atkinson, G. M., and D. M. Boore (2011). Modifications to existing ground-motion prediction equations in light of new data, Bull. Seism. Soc. Am. 101, , doi: / Boore, D. M., J. P. Stewart, E. Seyhan, and G. M. Atkinson (2014). NGA-West 2 equations for predicting PGA, PGV, and 5%-damped PSA for shallow crustal earthquakes, Earthq. Spectra 30, , doi: /070113EQS184M. Burbidge, D. R., Ed. (2012). The 2012 Australian Earthquake Hazard Map, Geoscience Australia Record 2012/71. Chiou, B. S.-J., and R. R. Youngs (2014). Update of the Chiou and Youngs NGA model for the average horizontal component of peak ground motion and response spectra, Earthq. Spectra 30, , doi: /072813EQS219M. Clark, D., M. Cupper, M. Sandiford, and K. Kiernan (2011). Style and timing of late Quaternary faulting on the Lake Edgar fault, southwest Tasmania, Australia: Implications for hazard assessment in intracratonic areas; In Audemard M., F. A., Michetti, A. M., and McCalpin, J. P., Eds., Geological criteria for evaluating seismicity revisited: Forty years of paleoseismic investigations and the natural record of past earthquakes, Geological Society of America. 479, doi: / (05). Clark, D., M. Leonard, J. Griffin, M. Stirling, and T. Volti (2016). Incorporating fault sources into the Australian National Seismic Hazard Assessment (NSHA) 2018, Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria. Clark, D., A. McPherson, M. Cupper, C. D. N. Collins, and G. Nelson (2015). The Cadell Fault, southeastern Australia: a record of temporally clustered morphogenic seismicity in a low-strain intraplate region; In Landgraf, A., Kübler, S., Hintersberger, E., and Stein, S., Eds., Seismicity, fault rupture and earthquake hazards in slowly deforming regions, Geological Society, London, Special Publications. 432, , doi: /SP Clark, D., A. McPherson, and R. Van Dissen (2012). Long-term behaviour of Australian stable continental region (SCR) faults, Tectonophys , 1-30, doi: /j.tecto Cuthbertson, R. J. (2016). Automatic determination of seismicity rates in Australia, Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria. Davies, G., and J. Griffin (2018). The 2018 Australian probabilistic tsunami hazard assessment: hazard from earthquake generated tsunamis, Geoscience Australia Record 2018/41, Canberra, doi: /Record The 2018 National Seismic Hazard Assessment

35 Davies, G., J. Griffin, F. Løvholt, S. Glimsdal, C. Harbitz, H. K. Thio, S. Lorito, R. Basili, J. Selva, E. Geist, and M. A. Baptista (2017). A global probabilistic tsunami hazard assessment from earthquake sources; In Scource, E. M., Capman, N. A., Tappin, D. R., and Wallis, S. R., Eds., Tsunamis: Geology, hazards and risks, Geological Society, London. 456, doi: /SP Dimas, V.-A., G. Gibson, and R. Cuthbertson (2016). Revised AUS6 model: Significant changes & approaches to the seismotectonic model, Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria. Dimas, V.-A., and S. Venkatesan (2016). Seismotectonic model for the Australian Plate beyond borders, Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria. Edwards, B., C. Cauzzi, L. Danciu, and D. Fäh (2016). Region-specific assessment, adjustment, and weighting of ground-motion prediction models: Application to the 2015 Swiss seismic-hazard maps, Bull. Seism. Soc. Am. 106, , doi: / Environmental Systems Research Institute (1998). ESRI shapefile technical description: An ESRI White Paper, Environmental Systems Research Institute, Redlands, CA, pp 28. Frankel, A. (1995). Mapping seismic hazard in the central and eastern United States, Seism. Res. Lett. 66, 8-21, doi: /gssrl Gardner, T., J. Webb, C. Pezzia, T. Amborn, R. Tunnell, S. Flanagan, D. Merritts, J. Marshall, D. Fabel, and M. L. Cupper (2009). Episodic intraplate deformation of stable continental margins: evidence from Late Neogene and Quaternary marine terraces, Cape Liptrap, Southeastern Australia, Quaternary Sci. Rev. 28, 39-53, doi: /j.quascirev Ghasemi, H., C. McKee, M. Leonard, P. Cummins, M. Moihoi, S. Spiliopoulos, F. Taranu, and E. Buri (2016). Probabilistic seismic hazard map of Papua New Guinea, Nat. Hazards 81, , doi: /s Griffin, J., and G. Davies (2018). Earthquake sources of the Australian plate margin: revised models for the 2018 national tsunami and earthquake hazard assessments, Geoscience Australia Record 2018/31, Canberra, doi: /Record Griffin, J., M. Gerstenberger, T. Allen, D. Clark, P. Cummins, R. Cuthbertson, V.-A. Dimas, G. Gibson, H. Ghasemi, R. Hoult, N. Lam, M. Leonard, T. Mote, M. Quigley, P. Somerville, C. Sinadinovski, M. Stirling, and S. Venkatesan (2018). Expert elicitation of model parameters for the 2018 National Seismic Hazard Assessment: Summary of workshop, methodology and outcomes, Geoscience Australia Record 2018/28, Canberra, doi: /Record Griffin, J., T. Volti, D. Clark, H. Ghasemi, M. Leonard, and T. Allen (2016). Development of the 2018 Australian National Seismic Hazard Assessment (NSHA), Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria. Gutenberg, B., and C. F. Richter (1944). Frequency of earthquakes in California, Bull. Seism. Soc. Am. 34, Hall, L., F. Dimer, and P. Somerville (2007). A spatially distributed earthquake source model of Australia, Australian Earthquake Engineering Society 2007 Conference, Wollongong, New South Wales. Hearn, S. J., and J. P. Webb (1984). Continental-scale felt effects of the large Banda Sea earthquake of 4 November 1963, Bull. Seism. Soc. Am. 74, Helmstetter, A., Y. Y. Kagan, and D. D. Jackson (2007). High-resolution time-independent grid-based forecast for M 5 earthquakes in California, Seism. Res. Lett. 78, 78-86, doi: /gssrl Irsyam, M., S. Widiyantoro, D. H. Natawidjaja, I. Meilano, A. Rudyanto, S. Hidayati, W. Triyoso, N. R. Hanifa, D. Djarwadi, L. Faizal, and Sunarjito (2017). Peta Sumber dan Bahaya Gempa Indonesia Tahun 2017, Kementerian Pekerjaan Umum dan Perumahan Rakyat, pp 376 (in Bahasa Indonesia). Leonard, M. (2008). One hundred years of earthquake recording in Australia, Bull. Seism. Soc. Am. 98, , doi: / Leonard, M., A. McPherson, and D. Clark (2012). Source zonation; In Burbidge, D. R., Ed. The 2012 Australian Earthquake Hazard Map. Geoscience Australia Record 2012/71, McCue, K. (2013). Darwin Northern Territory an earthquake hazard, Australian Earthquake Engineering Society 2013 Conference, Hobart, Tasmania. Model Input Files 29

36 Mote, T. I., M. L. So, and J. W. Pappin (2017). Arup NSHM - Australian National Seismic Hazard Model, Australian Earthquake Engineering Society 2017 Conference, Canberra, ACT. Pagani, M., D. Monelli, G. Weatherill, L. Danciu, H. Crowley, V. Silva, P. Henshaw, R. Butler, M. Nastasi, L. Panzeri, M. Simionato, and D. Vigano (2014). OpenQuake Engine: An open hazard (and risk) software for the Global Earthquake Model, Seism. Res. Lett. 85, , doi: / Pagani, M., V. Silva, A. Rao, M. Simionato, and R. Gee (2018). The OpenQuake-engine user manual Global Earthquake Model (GEM) Open-Quake Manual for Engine version 3.0.1, pp 198, doi: /GEM.OPENQUAKE.MAN.ENGINE Quigley, M. C., M. L. Cupper, and M. Sandiford (2006). Quaternary faults of south-central Australia: palaeoseismicity, slip rates and origin, Aust. J. Earth. Sci. 53, , doi: / Rajabi, M., M. Tingay, O. Heidbach, R. Hillis, and S. Reynolds (2017). The present-day stress field of Australia, Earth-Sci. Rev., doi: /j.earscirev Sandiford, M. (2003). Neotectonics of southeastern Australia: linking the Quaternary faulting record with seismicity and in situ stress; In Hillis, R. R., and Müller, R. D., Eds., Evolution and dynamics of the Australian Plate. Boulder, CO, Geological Society of America. Geol. Soc. Australia Spec. Publ. 22, and Geol. Soc. America Spec. Pap. 372, Sinadinovski, C., and K. McCue (2016). A proposed PSHA source zone for Australia, Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria. Somerville, P., R. Graves, N. Collins, S.-G. Song, S. Ni, and P. Cummins (2009). Source and ground motion models for Australian earthquakes, Australian Earthquake Engineering Society 2009 Conference, Newcastle, New South Wales. Standards Australia (2007). Structural design actions, part 4: Earthquake actions in Australia, Standards Australia AS , Sydney, NSW, pp 52. Storchak, D. A., D. Di Giacomo, I. Bondár, E. R. Engdahl, J. Harris, W. H. K. Lee, A. Villaseñor, and P. Bormann (2013). Public release of the ISC GEM global instrumental earthquake catalogue ( ), Seism. Res. Lett. 84, , doi: / Vanden Broek, P. H. (1980). Engineering geology of Darwin East, NT, Bureau of Mineral Resources Geology and Geophysics Bulletin 203. Weichert, D. H. (1980). Estimation of the earthquake recurrence parameters for unequal observation periods for different magnitudes, Bull. Seism. Soc. Am. 80, Youngs, R. R., and K. J. Coppersmith (1985). Implications of fault slip rates and earthquake recurrence models to probabilistic seismic hazard estimates, Bull. Seism. Soc. Am. 75, The 2018 National Seismic Hazard Assessment