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  • We have used data recorded by a temporary seismograph deployment to infer constraints on the state of crustal stress in the Flinders Ranges in south-central Australia. Previous stress estimates for the region have been poorly constrained due to the lack of large events and limited station coverage for focal mechanisms. New data allowed 65 events with 544 first motions to be used in a stress inversion to estimate the principal stress directions and stress ratio.While our initial inversion suggested that stress in the region was not homogeneous, we found that discarding data for events in the top 2km of the crust resulted in a well-constrained stress orientation that is consistent with the assumption of homogeneous stress throughout the Flinders Ranges. We speculate that the need to screen out shallow events may be due to the presence in the shallow crust of either: (1) small-scale velocity heterogeneity that would bias the ray parameter estimates, or (2) heterogeneity in the stress field itself, possibly due to the influence of the relatively pronounced topographic relief. The stress derived from earthquakes in the Flinders Ranges show an oblique reverse faulting stress regime, which contrasts with the pure thrust and pure strike slip regimes suggested by earlier studies. However, the roughly E-W direction of maximum horizontal compressive stress we obtain supports the conclusion of virtually all previous studies that the Flinders Ranges are undergoing E-W compression due to orogenic events at the boundaries of the Australian and Indian Plates.

  • Legacy product - no abstract available

  • Legacy product - no abstract available

  • 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.

  • 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.

  • A 'shake-map' represents the spatial distribution of macroseismic intensity resulting from an earthquake. These maps are often used to determine potential humanitarian consequences from scenario earthquakes, or in near-real time following the detection of an event. In the absence of dense strong-motion networks to calibrate real-time ground-shaking in many of the most vulnerable regions of the world, shake-maps are commonly generated using either Intensity Prediction Equations (IPEs) or Ground-Motion Prediction Equations (GMPEs) combined with Ground-Motion to Intensity Conversion Equations (GMICEs). There are several empirical models available to estimate the spatial distribution of intensity for an earthquake of given magnitude and location. However, these models can predict very different estimates of shaking intensity given the same input parameters; particularly at near-source distance ranges - the most critical distances for impact assessments. Consequently, the application of different shaking hazard model inputs can result in significantly different impacts. High-dimensional information visualisation techniques are used to study the mutual differences among different empirical intensity prediction models. We applied the Self-Organising Map (SOM) technique to project empirical prediction models onto a two-dimensional 'map' to visually compare the similarities and differences between models. The results clearly demonstrate the sensitivity of ground shaking to the selection of intensity prediction models. The effects of these sensitivities on earthquake impact assessments are investigated using a scenario event in Sumatra region, Indonesia.

  • This is the third volume of the isoseismal atlas compiled by Australian Geological Survey Organisation (AGSO) and contains an additional 119 Australian isoseismal maps of earthquakes that occurred between 1841and 1990. The atlas contains at least one map in every decade since the 1840s. A loose leaf binder format was adopted so additional maps could be inserted at a later time. Isoseismal maps in volume 3 and not in the first two volumes include those for: - the largest recorded earthquake in continental Australia - offshore WA on 19 November 1906 magnitude Ms 7.2 - the largest known earthquake in Eastern Australia - north east of Tasmania on 12 May 1885 magnitude MI 6.8 - the largest earthquake on Eyre Peninsula South Australia - 16 April 1887 magnitude ML(I) 5.7. - several small to moderate but important earthquakes in or near the major urban areas of Melbourne, Adelaide and Newcastle and - three Indonesian earthquakes felt in Northern Australia. Major earthquakes in the Indonesian Banda Arc shake tall buildings in Adelaide and Perth, some of which have generated tsunamis that sweep Australia's northwest coast which is why they are included in the atlas.

  • Legacy product - no abstract available