Slope failures with associated submarine slides, sediment accumulation along contourite drifts and focus seepage features have been interpreted from new sub-bottom profiler, multibeam bathymetry, side-scan sonar, echo-sounder data together with geochemical analyses of sediment samples along the continental slope off Western Australia. The processes recognised show the implication of slope instability and hydrocarbon seepage in shaping the continental slope geomorphology. The spatial correlation between regional seafloor features and reactivation of pre-existing faults suggests tectonics and seismic activity being the main potential triggering parameters for slope processes offshore northern Perth Basin. Geomechanical models have been used to test potential up-fault leakage using the present-day stress field and the results correlate with the seepage features observed in the study area. The marine survey results provide additional support for the presence of an active petroleum system in the northern Perth Basin; and combined with geomechanical models, the study helps reducing petroleum exploration and geohazards riks.

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.

This user guide describes the important instructions for using the Tasmanian Extreme Wind Hazard Standalone Tool (TEWHST). It aims to assist the Tasmanian State Emergency Service (SES) to view the spatial nature of extreme wind hazard (and how it varies depending on the direction of the extreme wind gusts). This information indicates detailed spatial texture for extreme hazard, which can provide guidance for understanding where the local-scale hazard (and impact) is expected to be the greatest for any particular event depending on the intensity and directional influence of the broad-scale severe storm. The tool provides spatial information at the local scale (25 metre resolution) of the return period extreme wind hazard (3-second gust at 10 metre height; variation with direction) where the broad-scale regional hazard is provided by the Australian and New Zealand Wind Loading Standard (AS/NZS 1170.2, 2002).

The Australian continent is actively deforming at a range of scales in response to far-field stresses associated with plate margins, and buoyancy forces associated with mantle dynamics. On the smallest scale (101 km), fault-related deformation associated with far-field stress partitioning has modified surface topography at rates of up to ~100 m / Myr. This deformation is evidenced in the record of historical earthquakes, and in the pre-historic record in the landscape. Paleoseismological studies indicate that few places in Australia have experienced a maximum magnitude earthquake since European settlement, and that faults in most areas are capable of hosting potentially catastrophic earthquakes with magnitudes in excess of 7.0. New South Wales is well represented in terms of its pre-historic earthquake record. Seismogenic faulting in the last 5-10 million years is thought to be responsible for locally generating up to 200 m of the contemporary topographic relief of the Eastern Highlands. Faults west of Sydney belonging to the Lapstone Structural Complex, and faults beneath the greater Sydney region, have been demonstrated to be associated with infrequent damaging earthquakes. . Decisions relating to the siting and construction of the built environment should therefore be informed with knowledge of the local neotectonics.

to follow

The inventory of over 200 fault scarps captured in GA's Australian neotectonics database, when grouped according to the spatial divisions prescribed in the recently published neotectonics domain model, allows for estimates of maximum magnitude earthquake (Mmax) to be calculated across the SCR crust of Australia. The 75th percentile value of fault scarp length for all features within a given domain was used in calculations using the average of a range of published relations. Results range between Mw 7.0 - 7.5 ± 0.2 magnitude units (Table 1), demonstrating that potentially catastrophic earthquakes are possible Australia-wide. These data form the basis for future seismic hazard assessments, including those for building design codes, both in Australia and analogous SCRs worldwide.

Geoscience Australia (GA) is currently undertaking a process of revising the Australian National Earthquake Hazard Map using modern methods and an updated catalogue of Australian earthquakes. This map is a key component of Australia's earthquake loading standard, AS1170.4. Here we present an overview of work being undertaken within the GA Earthquake Hazard Project and how it contributes to the next generation earthquake hazard map. Fundamental to any Probabilistic Seismic Hazard Assessment (PSHA) is knowledge of the recurrence and maximum magnitude of historic and pre-historic earthquakes. Palaeoseismological investigation of neotectonic features observed in the Australian landscape has lead to the development of a catalogue, from which we have derived a domains model to characterise the occurrence and style of seismicity for large intraplate earthquakes. The domains model suggests that earthquakes ranging between MW 7.0-7.5±0.2 can occur anywhere across the continent. In addition to gathering information on the pre-historic record, more rigorous statistical analyses of the spatial distribution of the historic catalogue are also being undertaken. Earthquake magnitudes in Australian catalogues were determined using disparate magnitude formulae, with many local magnitudes determined using Richter attenuation coefficients prior to about 1990. Consequently, efforts are underway to standardise magnitudes for specific regions and temporal periods. Finally, we will review the general procedure for updating the national earthquake hazard map, including consideration of Australian-specific ground-motion prediction equations. We will also examine the sensitivity of hazard estimates to the assumptions of certain model components in the hazard assessment.

Ground Motion Prediction Equations (GMPE) are a fundamental component of any seismic hazard analysis.

Abstract to go here

To achieve the RELACS Program's aim of improving the capabilities of the Rabaul Volcanological Observatory to locate and interpret volcano-related earthquake activity near Rabaul, a program of seismic field observation was undertaken in the Rabaul area by a consortium of institutions with significant experience in seismic work, viz AGSO, ANU, and the Universities of Hokkaido and Wisconsin. This Record describes post survey data processing of RELACS field data undertaken at the ANU, the University of Hokkaido and AGSO 1998-99. It also includes CDs of data files containing information on seismic recording stations, seismic shots, some earthquake locations, the arrival times of seismic waves, and seismic record files from stations in the international SUDS format.