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.

Probabilistic seismic hazard assessment (PSHA) is an important tool for reducing earthquake fatalities through land use planning, emergency management training based on credible earthquake scenarios, and improved building codes. The application of PSHA in Indonesia has seen rapid developmetn in the last few years, with development of a PSHA for Sumatra by Petersen et al. (2004), followed by PSHA of Java and Sumatra by Irsyam et al. (2008) and the most recent all-Indonesia PSHA developed by a group of Indonesian scientists known as "Team-9". These recent PSHA's for Indonesia show a generally increasing level of earthquake hazard, with the increase mainly associated with the new information avaialble on the earthquake activity of crustal faults, and, too a lesser extent, on intraslab earthquake activity. As part of a project to strengthen the Government of Indonesia's capacity to produce better PSHA's, we have used some of teh most recent information availble on earthquake activity and site response in the Indonesia province of Central Java. Our PSHA is implemented using an event-based approach to the calculation of seismic hazard, and it relised on geologic information on the slip rates of active crustal faults to define earthquake sources, and also on topography and surface geology informaiton to estimate site amplification. We will discuss our results in the context of extending its application to all of Indonesia.

The Asia-Pacific region is home to well over half the world's population and is also the focus of some of earth's most intense geological activity. It is no surprise therefore that geological hazards, in particular earthquake and volcano hazards, make the Asia-Pacific region the scene of som e of the worlds most lethal natural disasters. While this is evident form a perusal of historical data relating to natural disasters, it is not clear how well such historical data can be used as a guide for high -impact events that might be expected in the future. This uncertainty is due to (1) how poorly extreme geological events having long recurrence intervals are represented in the relatively short historical record, and (2) the failure of the historical record to account for recent demographic trends, in particular the explosive growth of population in the Asia -Pacific region and its rapid urbanisation during the 20 th century. We present here two novel techniques for assessing the potential impacts of volcanic and earthquake events on human population in the Asia Pacific region. For volcanic risk, we have calculated the frequency of large eruptions, aggregated for the countries of the Asia -Pacific region, using data provided by the Smithsonian Institution's Global Volcanism Program. These eruption frequ encies have been combined with an analysis of population data for the region to estimate the average number of people who might be affected, in the broad sense of death, injury or loss of essential services, by a major volcanic eruption. For earthquake, risk, we have considered that the potential future high -impact events will be driven by the probability that an earthquake might occur in or adjacent to one of the many megacities of the Asia -Pacific region. Earthquake probabilities near megacities are cal culated from catalogue data, and these are combined with a rough criterion for damage based on earthquake ground motion, to asses potentially affected populations. We present preliminary results of these analyses, which suggest the potential for earthquakes and volcanoes in the Asia-Pacific region to cause future `mega-disasters', for which affected populations may be much larger than the numbers indicated by the historical record.

Legacy product - no abstract available

Seismicity in the Australian region in 1989 was about average and the largest earthquake was that at Newcastle, which at magnitude ML 5.6, is the modal or most frequent annual maximum magnitude for mainland Australia. Another earthquake near Mt Olga, Northern Territory on 28 May had a similar size but their effects were dramatically different. Few people even felt the Mt Olga earthquake and only minor damage was reported by national park rangers at the tourist centre. The earthquake at Newcastle highlighted the difference between earthquake hazard and earthquake risk.

The Australian Seismological Report 2008 provides a summary of earthquake activity for Australia for 2008. It also provides a summary of earthquakes of Magnitude 5+ in the Australian Region, as well as an summary of Magnitude 6+ earthquakes worldwide. It has dedicated state and territory earthquake information including: largest earthquakes in the year; largest earthquakes in the state; and tables detailing all earthquakes detected by Geoscience Australia during the year. There are also contributions from Gary Gibson and Environmental Systems and Services describing Seismic Networks and providing Earthquake locations.

This story maps steps through Australia's history of significant earthquakes, plotted on an interactive story map. The map provides information on earthquakes, beginning with geological evidence of events that occurred up to 70 000 years ago, through to the earthquakes that have affected Australian communities in recent years.

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.

Each year in Australia there are on average one earthquake of magnitude 5.3 or greater and about 200 of magnitude 3 or greater, excluding aftershocks. The larger ones are a threat to life and property as was so tragically demonstrated by the 1989 Newcastle earthquake. Analysis of the small ones will yield clues to the cause, location and style of future large ones. This report contains information on the 1994 earthquakes and is the fifteenth compiled by the Australian Geological Survey Organisation (and its predecessor Bureau of Mineral Resources) since 1980. 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 new section on tsunamis has been added.