earthquakes
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This paper discusses two of the key inputs used to produce the draft National Earthquake Hazard Map for Australia: 1) the earthquake catalogue and 2) the ground-motion prediction equations (GMPEs). The composite catalogue used draws upon information from three key catalogues for Australian and regional earthquakes; a catalogue of Australian earthquakes provided by Gary Gibson, Geoscience Australia's QUAKES, and the International Seismological Centre. A complex logic is then applied to select preferred location and magnitude of earthquakes depending on spatial and temporal criteria. Because disparate local magnitude equations were used through time, we performed first order magnitude corrections to standardise magnitude estimates to be consistent with the attenuation of contemporary local magnitude ML formulae. Whilst most earthquake magnitudes do not change significantly, our methodology can result in reductions of up to one local magnitude unit in certain cases. Subsequent ML-MW (moment magnitude) corrections were applied. The catalogue was declustered using a magnitude dependent spatio-temporal filter. Previously identified blasts were removed and a time-of-day filter was developed to further deblast the catalogue.
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Pakistan has experienced several devastating earthquakes resulting in a large number of casualties and building damage. During the last six years, two damaging earthquakes struck different parts of the country, i.e., 2005 Kashmir earthquake and 2008 Baluchistan earthquake. They have provided an opportunity to assess the building performance under strong earthquakes, and have informed the development of a building inventory database. A comprehensive and accurate database of building inventory is a crucial part of earthquake risk assessment methodology and appropriate definition of building classification leads to a more accurate attribution of building vulnerability. For the present study area in Pakistan, typical building types are identified and, for the first time, a detailed database of the building inventory has been compiled for the country. The distribution of typical building types in all tehsils (administrative regions) of the country has been mapped in Geographical Information System (GIS) environment. The developed database has been validated in six field surveys, carried in selected cities of Pakistan. Results from these field surveys demonstrated the damage cases and identified the damage contributing parameters along with type of failure mechanisms which were observed in the above mentioned events. Furthermore, damage scenarios have been developed to estimate the extent of damage in the study area at micro and macro levels. The study presented here provides useful data layers for earthquake risk assessment at a national level in Pakistan and has a close relation with the recent developments in the field of earthquake risk assessment, i.e., USGS's Prompt Assessment of Global Earthquakes for Response (PAGER) and the Global Earthquake Model (GEM).
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System will not accept abstract. See TRIM link: D2011-143376
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The EQRM is Geoscience Australia's tool for conducting probabilistic seismic hazard and risk assessments. In this report we summarise the sensitivity of EQRM risk estimates to a range of input parameters. The importance of aleatory uncertainity is explored separately for the following components of the EQRM: synthetic earthquake catalogue generation, attenuation, regolith amplification and damage modelling. Different sampling techniques are analysed for incorporating aleatory uncertainty. Event and hazard based approaches to risk estimation are compared. Finally, we demonstrate the impact of using different attenuation models on risk estimates.
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The Sydney Basin encloses a significant proportion of the Australian population, and the 1989 M5.6 Newcastle earthquake demonstrated that the basin is not immune from the impact of even relatively modest earthquakes. In spite of this, few investigations have been conducted to identify and characterise potential geologic sources of strong ground shaking. A recent major study of the southern part of the basin commented that - The available data are less complete than ideal for the purposes of probabilistic seismic hazard analysis. - Essentially, the extreme infrequency of large earthquake events in intraplate regions, such as Australia, means that the short historic record of seismicity is poorly suited to the task of assessing seismic hazard. Hence, geologic, geomorphic and paleoseismic knowledge has a vital role to play in obtaining constraint on the probable location and recurrence of large and damaging earthquakes near Sydney. In April 2005 a one day workshop at the University of Sydney brought together a diverse range of researchers with experience in the geology and geomorphology of the Sydney Basin, neotectonics and seismic hazard science. A series of seminars were presented covering geology, geomorphology, seismicity and seismic hazard. These served as a nucleation point for subsequent discussion, and the drafting of the papers presented herein. This proceedings volume contains within its covers tools for understanding large earthquake occurrence within the Sydney Basin and compiles 12 papers addressing landscape and structural developement, and seismic hazard aspects, of the Lapstone Structural Complex west of Sydney. Hence, it represents a framework upon which future advances in our understanding of the seismic hazard posed to Australia's largest population centre may be based.
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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.
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Legacy product - no abstract available
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The Earthquake hazard map of Australia 1991 was prepared by members of the Standards Australia Working Group BD/6/4/1 based on the hazard analysis of Gaull, Michael-Leiba and Rynn (1990). Reference: Probabilistic earthquake risk maps of Australia, Australian Journal of Earth Sciences,37, 169-187.