Legacy product - no abstract available

Legacy product - no abstract available

The Global Earthquake Model (GEM) is a public/private partnership to develop a global understanding of earthquake risk. Its purpose is to establish an independent, uniform standard for calculating and communicating earthquake risk, and to use this information to reduce earthquake losses worldwide. The 5-year program, which was formally incorporated in late 2008, has a budget of 35 million Euros, of which about 21 million Euros have been identified. The program will focus on three main modules: earthquake hazard, earthquake risk and socio-economic impact. In March 2009, Geoscience Australia hosted a kick-off meeting for GEM1, the first phase of the GEM program. GEM1 is aimed at developing an initial set of hazard and risk products as a proof of concept based on available tools, databases and information. Over 30 scientists and engineers from 18 countries participated in the workshop. At the first GEM Outreach meeting held in Hohenkammer, Germany in June 2009, there were approximately 120 participants from over 40 countries. This meeting was the first opportunity to explore the development of a series of regional initiatives that will be necessary to complement the development of core capability. I will present an overview of the development of GEM, including some of the main issues and priorities, as well the opportunities for and potential benefits of Australian participation.

This report contains information on earthquakes of Richter magnitude 3 or greater that were reported in the Australian region during 1990. It is the eleventh of an annual series compiled by the Australian Geological Survey Organisation (AGSO), using data from AGSO and various seismological agencies in Australia. Its purposes are to aid the study of earthquake risk in Australia, and to provide information on Australian and world earthquakes for scientists, engineers and the general public. The report has six main sections: Australian region earthquakes; Isoseismal maps; Network operations; Accelerograph data; Principal world earthquakes; and Monitoring of nuclear explosions.

Stress Tensor reconstructions are presented for seven domains withinthe Australian crust based on formal inversion of four or more earthquake focal mechanisms in close geographic proximity. The data for inversion was sourced from a set of sixty-nine quality-ranked focal mechanisms forming part of the recently compiled AGSO focal mechanism database. When analysed in conjunction with in situ stress data held by the Australian Stress Map project, the new data makes possible for the first time a rigorous comparison of the Australian continental stress field at near-surface and seismogenic depths. A more complete picture of the character of the Australian intraplate stress field is thereby made available. The tensor data agrees well with in situ determinations in western, northern and far southeastern Australia suggesting that the continental stress field is homogeneous between shallow and seismogenic depth in these areas. Plate boundary forces are considered to be the dominant source of stress. In contrast, the results for the Sydney Basin and Flinders Ranges imply significant heterogeneity and influence by more localised sources of stress.

The Indonesia Earthquake Hazard Program (IEHP) is a four-year project aimed at enhancing the capacity of the Government of Indonesia (GoI) to undertake earthquake hazard and risk assessments. The IEHP is a joint collaboration between the Australia-Indonesia Facility for Disaster Reduction (AIFDR), the GoI, Indonesian Universities and Geoscience Australia.

Australia boasts arguably the richest Quaternary faulting record of all the world's SCR crust. Extensive consultation with the earth science community, and recent advances in digital elevation model coverage, have allowed the compilation of an inventory of over 200 landscape features consistent with fault scarps relating to Quaternary surface breaking earthquakes. This record, together with a growing database of palaeoseismicity data, permits analysis of the long term behaviour of SCR faults in different geologic settings. Details of variations in palaeoearthquake magnitude (including maximum magnitude), recurrence characteristics (given appropriate scaling relations and assumptions relating to landscape modification rates) and spatial relationships between scarps in different deforming regions are recoverable. A common characteristic across Australia appears to be the temporal clustering of large earthquakes. Active periods of earthquake activity comprising a finite number of large events are separated by much longer periods of seismic quiescence. This episodic behaviour poses problems for probabilistic seismic hazard assessments (PSHAs) in that it implies that recurrence of large earthquake events is not random (Poisson). The points critical to understanding the hazard posed by such faults, and modelling this hazard probabilistically, become: 1) is the SCR fault in question about to enter an active period, in the midst of an active period, or in a quiescent period, 2) how many large events might constitute an active period, and how many previous ruptures has the fault generated in its current active period (should it be in one), and 3) what is the 'average' recurrence interval in an active period, and what is the variability around this average. This 'average' can be incorporated statistically into PSHAs, and must be considered when palaeoearthquake catalogues are combined with historic records.

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. South Australia 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 generating more than 30-50% of the contemporary topographic relief separating the highlands of the Flinders and Mt Lofty Ranges from adjacent plains, and perhaps as much as a third of the strain budget of the entire continent is accommodated there. Adelaide itself straddles several faults which are arguably some Australia's most active. Decisions relating to the siting and construction of the built environment should therefore be informed with knowledge of the local neotectonics.

Legacy product - no abstract available

In plate boundary regions moderate to large earthquakes are often sufficiently frequent that robust estimates of fundamental seismic parameters such as the recurrence intervals of large earthquakes and maximum credible earthquake (Mmax) can be made. The same is not true for the Stable Continental Regions (SCRs) of the world. Large earthquakes are so infrequent that the data distributions upon which recurrence and Mmax estimates are based are heavily skewed towards magnitudes below Mw 5.0, and so require significant extrapolation up to magnitudes for which damaging ground-shaking might be expected. The rarity of validating evidence from palaeo-surface rupturing earthquakes limits the confidence with which extrapolated statistical parameters may be applied. Herein we present an earthquake catalogue containing, 150 palaeo-earthquakes, from 60 palaeo-earthquake features, based upon a >100 ka record of palaeo-earthquakes recorded in the Precambrian Shield of southwest Western Australia. From this data we show that Mmax for non-extended-SRC is well constrained at M7.22 and M7.65 for extended-SCR. In non-extended-SRC the earthquakes are likely episodic with periods of quiescence of 10-100ka in between active phases. The largest earthquakes are likely to occur on pre-existing faults. We expect these results might apply to most areas of non-extended-SCR worldwide.