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On 23 March 2012, at 09:25 GMT, a MW 5.4 earthquake occurred in the eastern Musgrave Ranges region of north-central South Australia, near the community of Ernabella (Pukatja). Several small communities in this remote part of central Australia reported the tremor, but there were no reports of injury or significant damage. This was the largest earthquake to be recorded on mainland Australia for the past 15 years and resulted in the formation of a 1.6 km-long surface deformation zone comprising reverse fault scarps with a maximum vertical displacement of over 0.5 m, extensive ground cracking, and numerous rock falls. The maximum ground-shaking is estimated to have been in the order of MMI VI. The earthquake occurred in non-extended Stable Continental Region (SCR) cratonic crust, over 1900 km from the nearest plate boundary. Fewer than fifteen historic earthquakes worldwide are documented to have produced co-seismic surface deformation (i.e. faulting or folding) in the SCR setting. The record of surface deformation relating to the Ernabella earthquake therefore provides an important constraint on models relating surface rupture length to earthquake magnitude. Such models may be employed to better interpret Australia's rich prehistoric record of seismicity, and contribute to improved estimates of seismic hazard.

This paper describes the methods used to define earthquake source zones and calculate their recurrence parameters (a, b, Mmax). These values, along with the ground motion relations, effectively define the final hazard map. Definition of source zones is a highly subjective process, relying on seismology and geology to provide some quantitative guidance. Similarly the determination of Mmax is often subjective. Whilst the calculation of a and b is quantitative, the assumptions inherent in the available methods need to be considered when choosing the most appropriate one. For the new map we have maximised quantitative input into the definition of zones and their parameters. The temporal and spatial Poisson statistical properties of Australia's seismicity, along with models of intra-plate seismicity based on results from neotectonic, geodetic and computer modelling studies of stable continental crust, suggest a multi-layer source zonation model is required to account for the seismicity. Accordingly we propose a three layer model consisting of three large background seismicity zones covering 100% of the continent, 25 regional scale source zones covering ~50% of the continent, and 44 hotspot zones covering 2% of the continent. A new algorithm was developed to calculate a and b. This algorithm was designed to minimise the problems with both the maximum likelihood method (which is sensitive to the effects of varying magnitude completeness at small magnitudes) and the least squares regression method (which is sensitive to the presence of outlier large magnitude earthquakes). This enabled fully automated calculation of a and b parameters for all sources zones. The assignment of Mmax for the zones was based on the results of a statistical analysis of neotectonic fault scarps.

Natural hazards pose a serious threat to the lives and livelihoods of people living in developing countries throughout the Asia-Pacific region. One of the key mechanisms for reducing the impact of these events is to build capacity in these countries to mitigate for natural hazards. An improved understanding of natural hazards and the implementation of reliable, widely-tested computational models for assessing hazard will ultimately assist in disaster preparedness and response. Geoscience Australia (GA) in collaboration with the Australian Agency for International Development (AusAID) conducted a six day pre-IGC natural hazard modelling workshop for ASEAN and Pacific country delegates. The aim of the workshop was to improve their understanding of computational modelling techniques for volcanic ash, earthquake, tsunami and tropical cyclone hazards. The outcomes and lessons learnt will be discussed. Forty delegates from ASEAN and Pacific countries were invited to attend and receive training in one of four hazard modelling software programs relevant to the region: python-FALL3D (volcanic ash), ANUGA (tsunami), OpenQuake (earthquake) or TCRM (tropical cyclone). Relevance to their current employment area and the capacity to share the knowledge obtained through the training with colleagues were key criteria in selecting participants. Take home versions of the modelling software on USB stick and access to ongoing technical assistance from GA staff ensure that participants will be able to continue utilising the modelling software after the workshop. The knowledge gained will ultimately build the capacity of participants who have the responsibility of planning for potential natural hazards in their home countries.

The Australian Flood Studies Database is available on line by Geoscience Australia via the Australian Flood Risk Information Portal. The database provides metadata on Australian flood studies and information on flood risk with a digital version where available. The purpose of the document is to guide new users in data entry and uploading of flood studies to a level acceptable for inclusion in the database.

Geoscience Australia, the Western Australian Department of Planning and the Western Australian Planning Commission have collaborated through this study to develop a regional-scale inundation model capable of simulating combined storm tide and riverine flood scenarios within current and future climate conditions (sea-level rise influences only). Modelling scenarios were applied to the Busselton region of Western Australia.

Stochastic finite-fault ground-motion prediction equations (GMPEs) are developed for the stable continental region of southeastern Australia (SEA). The models are based on reinterpreted source and attenuation parameters for small-to-moderate magnitude local earthquakes and a dataset augmented with ground-motion records from recent well-recorded moderate-magnitude earthquakes relative to those used in prior studies (Allen et al., 2007). The models are applicable for median horizontal-component ground-motions for earthquakes 4.0 <= MW <= 7.5 and at rupture distances less than 400 km. Careful analysis of well-constrained Brune stress drops indicates a dependence on hypocentral depth. It is speculated that this is the effect of an increasing crustal stress profile with depth. However, rather than a continuous increase, the change in stress drop appears to indicate a discrete step near 10 km depth. Average Brune stress drops for SEA earthquakes shallower and deeper than 10 km are estimated to be 23 MPa and 50 MPa, respectively. These stress parameters are subsequently input into the stochastic ground-motion simulations for the development of two discrete GMPEs for shallow and deep events. The GMPEs developed estimate response spectral accelerations similar to the Atkinson and Boore (2006) GMPE for eastern North America (ENA) at short rupture distances (less than approximately 100 km). However, owing to higher attenuation observed in the SEA crust (Allen and Atkinson, 2007), the SEA GMPEs estimate lower ground-motions than ENA models at larger distances. These differences become most obvious at distances greater than 200 km. A correlation between measured near-surface shear-wave velocity (VS30) and the site-dependent diminution term (K0) was developed from the limited data available to determine the average site condition to which the GMPEs are applicable. Assuming the correlation holds, a VS30 of approximately 820 m/s is obtained assuming an average path-independent diminution term K0 of 0.006 s from SEA seismic stations. Consequently, the GMPE presented herein can be assumed to be appropriate for rock sites of B to BC site class in the modified National Earthquake Hazards Reduction Program (Wills et al., 2000; Building Seismic Safety Council, 2003) site classification scheme. The response spectral models are compared against moderate-magnitude (4.0 <= MW <= 5.3) earthquakes from eastern Australia. Overall the SEA GMPEs show low median residuals across the full range of spectral period and distance. In contrast, ENA models tend to overestimate response spectra at larger distances. Because of these differences, the present analysis justifies the need to develop Australian-specific GMPEs where ground-motion hazard from a distant seismic source may become important.

This report is a major risk assessment project based on metropolitan Perth, the capital city of Western Australia. Completed in June 2005, the report is the final publication in Geoscience Australia's Cities Project. Approximately 72% of Western Australia's population of around 1.3 million live in the Perth metropolitan area. Significant areas of Perth are situated along the banks of the flood prone Swan River and close to Australia's most active earthquake zone. There are several limestone belts to the north and south of Perth where karst systems have been discovered and the city's coastline suffers from coastal erosion as a result of high winds and fierce storms. The study aimed at estimating the impact on the Perth community of several sudden-onset natural hazards. The natural hazards considered are both meteorological and terrestrial in origin. The hazards investigated most comprehensively are riverine floods in the Swan and Canning Rivers, severe winds in metropolitan Perth, and earthquakes in the Perth region. Some socioeconomic factors affecting the capacity of the citizens of Perth to recover from natural disaster events have been analysed and the WA data compared with data from other Australian states. Additionally, new estimates of earthquake hazard have been made in a zone of radius around 200km from Perth, extending east into the central Wheatbelt. The susceptibility of the southwest WA coastline to sea level rise from climate change has also been investigated. A commentary on the tsunami risk to WA coastline communities is also included. A postage and handling fee will be associated with the distribution of this product.

This isoseismal data shows the distribution of the shaking effects of earthquakes that were felt in Australia between 1841 and 2003. The data was captured from maps collated in the Geoscience Australia record "Atlas of Isoseismal Maps of Australian Earthquakes" compiled by K.F. McCue and supplimented with data from recent Centre for Earthquake Research Australia (CERA) reports and other unpublished data. Data present include felt values (points) and isoseismal contours (lines) from 405 earthquake events in an attributed GIS Dataset.

This set of Australian landslide images illustrates the causes of landslides, both large and small, and other earth movements. A set of 15 slides with explanatory text; includes images of Thredbo, NSW, Sorrento Vic., Gracetown WA and Tasmania.