Legacy product - no abstract available

A dataset comprising some 260 seismograph and accelerograph records from 67 events of the Burakin 2001-02 earthquake sequence was compiled to develop regional ground-motion models for southwestern Western Australia. Events range in size from moment magnitude 2.3 - M - 4.6. The decay of spectral amplitudes can be approximated by a geometrical spreading coefficient of R-1.05 within 80 km of the source. The associated model for the regional seismic quality factor can be expressed as Q(f) = 290f1.09. These attenuation parameters are subsequently used to evaluate average source parameters for the 67 earthquakes. For the observed magnitude range, data demonstrates a seismic moment (M0) - local magnitude (ML) relation following: log M0 = 1.14 ML + 10.45, where M0 is in N-m. Average corner frequencies for these events do not vary significantly with M0 particularly for events M > 3.0, chiefly ranging between 2-3 Hz. This gives rise to anomalously low stress drops for lower magnitudes (M < 4.0) that increase at larger magnitudes.

A bullentin outlining the seismicity and earthquake risk in Eastern Australia. The topics covered include:The Structure of the Crust and Upper Mantle Beneath Southeastern Australia. Seismic Risk in New South Wales. Geological Appreciation of the Seismicity of the Southern Portion of the Sydney Basin . The Picton Earthquake of 9 March 1973: A Seismic View of the Source. Effects of the 1973 Picton and Other Earthquakes in Eastern Australia Appendix 1: Claim Details Provided by the Fire and Underwriters Association of New South Wales. Some Structural Damage Caused by the 1973 Picton Earthquake. Seismotectonics of South Australia and Earthquake Trends. The Eden Fault and Its Effect on the Development of Adelaide. Progress Report on Seismic Zoning in Australia. Dynamic Response of Black Mountain Tower to Estimated Ground Motions. Seismic Considerations Affecting the Safety of Nuclear Plant. The Role of Local Geology in Seismic Intensity Predictions. Seismic Effects on Nuclear Power Plants The Effect of Large Dams on Earthquake Risk.

Legacy product - no abstract available

The Meeberrie earthquake is the largest known onshore Australian earthquake. Its magnitude was ML 7.2 and it was felt over a wide area of Western Australia as shown on the isoseismal map below, from Port Hedland in the north to Albany and Norseman in the south. Damage from the earthquake was small because of the low population density in the epicentral region, but the shaking at Meeberrie homestead was very severe; all the walls of the homestead were cracked, several rainwater tanks burst, and widespread cracking of the ground occurred. Minor non-structural damage was reported in Perth more than 500km away from the epicentre.

Australia boasts arguably the richest Quaternary faulting record in all of the world's stable continental region (SCR) crust. Significant variation in Quaternary fault scarp length, vertical displacement, relation to other faults and to topography, justifies the division of the continent according to fault character. Six onshore 'neotectonic domains' are recognised. Each domain relates to a distinct underlying crustal type and architecture, which can be broadly assigned to the classes: cratonic, non-cratonic and extended. In general, as has previously been recognised, higher activity is associated with extended crust than with non-extended crust. Application of this domains model permits greater confidence in identifying analogous systems elsewhere in the world. A common characteristic across Australia appears to be the temporal clustering of large earthquakes - periods of earthquake activity comprising a finite number of large events are separated by much longer periods of seismic quiescence. In several instances there is evidence for deforming regions at scales of several hundred kilometres switching on and off over the last several million years. What is not clear from the limited available paleoseismic data is whether successive active periods are comparable in terms of slip, number of events, magnitude of events, etc. Irrespective, this apparent bimodal recurrence behaviour poses problems for probabilistic seismic hazard assessment (PSHA) in that it implies that large earthquake recurrence is not random (i.e. Poissonian). The points critical to understanding the hazard posed by SCR faults, and modelling this hazard probabilistically, become: 1) is the fault in question 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 ruptures has the fault generated so far in its current active period (should it be in one); and 3) what is the mean recurrence interval in an active period, and what is the variability around this mean? This data might be, with caution, incorporated statistically into PSHAs. Keywords: intraplate, neotectonics, palaeoseismology, temporal clustering

We describe a weighted-average approach for incorporating various types of data (observed peak ground motions and intensities, and estimates from ground motion prediction equations) into the ShakeMap ground motion and intensity mapping framework. This approach represents a fundamental revision of ShakeMap technique, particularly as it pertains to processing ground motion and intensity data. Combining ground motion and intensity data onto composite ShakeMaps proves invaluable for loss calibration of historical events as well as for loss estimation in near-real time applications. In addition, the increased availability of near-real-time macroseismic intensity data, the development of new relationships between intensity and peak ground motions, and new relationships to directly predict intensity from earthquake source information, have facilitated the inclusion of intensity measurements directly into the ShakeMap computations. Our approach allows for the possible combination of all of the following data sources and estimates: 1) nearby observations (ground motion measurements and reported intensities), 2) converted observations from intensity to ground motion (or vice-versa), and 3) estimated peak ground motions from prediction equations (or numerical estimates).

Legacy product - no abstract available

Legacy product - no abstract available

Joint seismic tomography exploiting P and S wave arrivals conducted before the 2011 Offshore Tohoku earthquake reveals an area comparable to the faulting surface for the 2011 March 11 event with different properties from other areas along the shallow part of the subduction zone. The differences are revealed by using a measure R of the relative variations in shear wavespeed and bulk-sound speed. Within the faulting area there are patches on the subduction zone with slightly reduced S wavespeed, and thus negative R, that appear to separate portions of the rupture with very different character. On the down-dip side there is strong short-period radiation, whilst the largest slip occurs up-dip with most energy release at longer periods. Segmentation of the slip process can be imaged by back projection of seismograms from the US Array; the areas of greatest energy release at short periods lie down-dip from the negative R anomalies. The main seismic moment release from broad-band seismograms lies on the updip side of the same anomalies. The structural variations on the subduction zone thus separate two regions with fundamental differences in the rupture process, stronger long-period radiation up-dip and stronger short-period radiation down-dip. These variations are likely to reflect features brought into the subduction zone, which may have acted as asperities that allowed this event to build up 30-40 m of strain in the near trench zone, making it much bigger than expected. Thus minor changes in the character of the subducted plate can have a significant influence on the behaviour of a great earthquake.