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  • <p>A new finite volume algorithm to solve the two dimensional shallow water equations on an unstructured triangular mesh has been implemented in the open source ANUGA software, which is jointly developed by the Australian National University and Geoscience Australia. The algorithm supports discontinuous-elevation, or 'jumps' in the bed profile between neighbouring cells. This has a number of benefits compared with previously implemented continuous-elevation approaches. Firstly it can preserve stationary states at wet-dry fronts without using any mesh porosity type treatment. It can also simulate very shallow frictionally dominated flow down sloping topography, as typically occurs in direct-rainfall flood models. In the latter situation, mesh porosity type treatments lead to artificial storage of mass in cells and associated mass conservation issues, whereas continuous elevation approaches with good performance on shallow frictionally dominated flows tend to have difficulties preserving stationary states near wet-dry fronts. The discontinuous elevation approach shows good performance in both situations, and mass is conserved to a very high degree, consistent with floating point error. <p>A further benefit of the discontinuous-elevation approach, when combined with an unstructured mesh, is that the model can sharply resolve rapid changes in the topography associated with e.g. narrow prismatic drainage channels, or buildings, without the computational expense of a very fine mesh. The boundaries between such features can be embedded in the mesh using breaklines, and the user can optionally specify that different elevation datasets are used to set the elevation within different parts of the mesh (e.g. often it is convenient to use a raster DEM in terrestrial areas, and surveyed channel bed points in rivers). <p>The discontinuous elevation approach also supports a simple and computationally efficient treatment of river walls. These are arbitrarily narrow walls between cells, higher than the topography on either side, where the flow is controlled by a weir equation and optionally transitions back to the shallow water solution for sufficiently submerged flows. This allows modelling of levees or lateral weirs much finer than the mesh size. <p>A number of benchmark tests are presented illustrating these features of the algorithm, along with its application to urban flood hazard simulation and comparison with field data. All these features of the model can be run in serial or parallel, on clusters or shared memory machines, with good efficiency on 10s - 100s of cores depending on the number of mesh triangles and other case-specific details.

  • Bookmark developed during the year of the 30th anniversary of the Newcastle earthquake and used to raise awareness of earthquakes and to provide information on what to do in an earthquake. As Geoscience Australia jointly operates the Joint Australian Tsunami Warning Centre with the Bureau of Meteorology, the bookmark also provides information on tsunami safety. Geoscience Australia identifies and characterises potentially tsunamigenic earthquakes and this information is used to initiate the tsunami warning chain.

  • Tsunamis pose considerable risk to coastal communities around the globe and understanding this risk is a key aspect of emergency management and risk reduction. This paper explores the nature and extent of tsunami hazard to NSW coastal communities and informs tsunami emergency planning and management. We outline the results of recent risk scoping which have examined sources of tsunami hazard, and tsunami history together with results of inundation studies for selected sites and discuss the level of tsunami risk to these NSW communities. We also outline how the results have complimented research by the Australian Bureau of Meteorology in confirming tsunami warning thresholds for NSW. Work undertaken to date indicates the coast of NSW has a moderate tsunami hazard level. Whilst historical impact of tsunami inundation in NSW has been relatively minor, and generally restricted to marine based events, the modelling of selected earthquake generated events indicates the potential for land inundation particularly at high (rare) return periods. Low lying populated communities around estuary foreshores are particularly at risk although results also indicate the potential for inundation of open coast sites at very high (very rare) return periods. The results confirm the need for and support the ongoing collaborative development of emergency management arrangements for tsunami.

  • Using the wind multiplier code (https://pid.geoscience.gov.au/dataset/ga/82481) and an appropriate source of classified terrain data, wind multipliers for all of Queensland at (approximately) 25 metre resolution were created. The wind multipliers have been used to guide impact assessments as part of the Severe Wind Hazard Assessment for Queensland.

  • Tropical cyclone return period wind hazard layers developed using the Tropical Cyclone Risk Model. The hazard layers are derived from a catalogue of synthetic tropical cyclone events representing 10000 years of activity. Annual maxima are evaluated from the catalogue and used to fit a generalised extreme value distribution at each grid point.

  • Hot emissions of mainly sulphur dioxide and carbon dioxide took place from a mound in Koranga open cut, near Wau, following a landslide at the end of May, 1967. Rocks of the Holocene volcano, Koranga, are exposed in the open cut. The emissions lasted about three months, and ceased on 13 August after another landslide removed the active mound. During the period of activity, recorded temperatures ranged up to 680°C; no anomalous seismic or tilt phenomena were recorded. The cause of the activity is not known, but it is thought that the high temperatures and gases may have been the result of the spontaneous combustion of reactive sulphides and carbonaceous material present in the altered rocks of Koranga volcano.

  • One-dimensional shear-wave velocity (VS ) profiles are presented at 50 strong motion sites in New South Wales and Victoria, Australia. The VS profiles are estimated with the spectral analysis of surface waves (SASW) method. The SASW method is a noninvasive method that indirectly estimates the VS at depth from variations in the Rayleigh wave phase velocity at the surface.

  • The TCRM Stochastic Event Catalogue contains artificially generated tropical cyclone tracks and wind fields representing 10000 years of tropical cyclone activity. The catalogue is stored by year, with a track file and wind field file. The wind field file contains the maximum wind speed from all events occuring in the corresponding track file (i.e. it represents annual maximum wind speeds).

  • An understanding of the vulnerability of the built environment to ground shaking is vital to the impact and risk assessment process. The vulnerability of Unreinforced Masonry (URM) buildings to earthquake hazard as been repeatedly demonstrated around the world. A portion of Australia's building stock is made up of legacy URM buildings dating from before the First World War. These buildings are typical of inner-city suburbs and the centres of country towns. The Kalgoorlie Earthquake of 20 April, 2010 offered the best opportunity to study the vulnerability of Australian URM buildings to ground shaking since the Newcastle Earthquake in 1989. The Kalgoorlie earthquake caused shaking of MMI intensity VI in Boulder and intensity V in Kalgoorlie. Damage was principally confined to turn-of-the-century URM buildings with only slight damage observed in more modern cavity masonry domestic residential buildings. Geoscience Australia led a post-event field survey to record damage to buildings in Boulder - Kalgoorlie. The survey recorded street-view imagery of the entire urban area and subsequently a detailed survey template was complete during a door-to-door foot survey. The foot survey targeted the entire population of turn-of-the-century buildings in Boulder-Kalgoorlie together with a sample of modern cavity masonry domestic residential buildings. The aim of the foot survey was to capture sufficient information to enable the calculation of a damage index (or loss ratio) for each surveyed building. The survey and subsequent analysis revealed an average damage index for turn-of-the-century URM buildings of 0.062 in Boulder (MMI VI) and 0.019 in Kalgoorlie (MMI V). These values are slightly higher than those reported post-Newcastle for ? . Difficulties encountered with computing damage indices for individual buildings are enumerated and recommendations are presented to improve future post-earthquake population surveys.

  • Through Australian Department of Foreign Affairs and Trade, Geoscience Australia has been working closely with the Government of Papua New Guinea technical agencies (Rabaul Volcano Observatory, Port Moresby Geophysical Observatory, and Engineering Geology Branch) since September 2010 to enhance their capabilities to monitor and assess natural hazards. The objective of this program is to support the Government of Papua New Guinea in developing fundamental information and practices for the effective response and management of natural hazard events in PNG. Earthquakes as natural hazards are one of the key focus points of this project, as they continue to cause loss of life and widespread damage to buildings and infrastructure in Papua New Guinea. The country’s vulnerability to earthquakes is evident from the significant socio-economic consequences of recent major events in Papua New Guinea, e.g., a magnitude 7.5 earthquake that occurred in the Hela Province of Papua New Guinea in 2018. Earthquake risk is likely to increase significantly in the years to come due to the growth in population and urbanization in Papua New Guinea. However, earthquake risk, unlike hazard, can be managed and minimized. One obvious example would be minimizing earthquake risk by constructing earthquake-resistant structures following building standards. The high level of earthquake hazard of Papua New Guinea has been long recognised and the suite of building standards released in 1982 contained provisions to impart adequate resilience to buildings based on the best understanding of seismic hazard available at that time. However, the building standards and incorporated seismic hazard assessment for Papua New Guinea has not been updated since the 1980s. The integration of modern national seismic hazard models into national building codes and practices provides the most effective way that we can reduce human casualties and economic losses from future earthquakes. This report aims at partially fulfilling this task by performing a probabilistic seismic hazard assessment to underpin a revision of the earthquake loading component of the building standards of Papua New Guinea. The updated assessment offers many important advances over its predecessor. It is based on a modern probabilistic hazard framework and considers an earthquake catalogue augmented with an additional four decades-worth of data. The revised assessment considers advances in ground-motion modelling through the use of multiple ground-motion models. Also, for the first time, the individual fault sources representing active major and microplate boundaries are implemented in the input hazard model. Furthermore, the intraslab sources are represented realistically by using the continuous slab volume to constrain the finite ruptures of such events. This would better constrain the expected levels of ground motion at any given site in Papua New Guinea. The results suggest a high level of hazard in the coastal areas of the Huon Peninsula and the New Britain–Bougainville region, and a relatively low level of hazard in the southern part of the New Guinea Highlands Block. In comparison with the seismic zonation map in the current design standard, it can be noted that the spatial distribution used for building design does not match the bedrock hazard distribution of this study. In particular, the high seismic hazard of the Huon Peninsula in the revised assessment is not captured in the current seismic zoning map, leading to a significant under-estimation of hazard in PNG’s second-largest city, Lae. It can also be shown that in many other regions and community localities in PNG the hazard is higher than that regulated for the design of buildings having a range of natural periods. Thus, the need for an updated hazard map for building design has been confirmed from the results of this study, and a revised map is developed for consideration in a revised building standard of Papua New Guinea.