For Indonesian Geophyscis conference (HAGI)

The paucity of ground-motion data in Stable Continental Regions (SCRs) remains a key limitation when developing relations that seek to predict effects of strong ground-shaking from large damaging earthquakes. It is desirable to combine data from more than one SCR in order to increase database size, but this raises questions as to whether the source and attenuation properties of the SCRs are equivalent. We merge recently - compiled spectralamplitude databases from small-to-moderate events (moment magnitudes 2.0< - 5.0<) in both southeastern Australia and eastern North America in order to compare the key characteristics of ground motion in these two regions. Both are SCRs, but are widely separated, spatially and in tectonic history.

We describe the use of a temporary seismometer deployment to monitor local earthquakes in the Flinders Ranges, South Australia. 16 seismograph stations were deployed over a 200 x 100 km area, which is one of the most seismically active regions in Australia. The instrumentation consisted of short-period and broadband Guralp seismometers combined with Reftek and Kelunji data loggers, which sample data continuously at 100-200 sps. Analysis of data from the period Sept.-Dec., 2003, resulted in the determination of hypocentres for over 175 earthquakes, most of which could not be located using PIRSA's permanent network. 54 of these earthquakes had depths resolved at 10 km or greater, and the proportion of deep events appears to increase from the southern to the northern part of the Flinders Ranges. The largest earthquake, ML-4, occurred near Hawker on 22 November, 2003, and has a depth of 17±2 km, and a well-resolved normal focal mechanism.

One of Australia's most serious natural disasters occurred when an earthquake shook Newcastle in New South Wales, leaving 13 people dead and injuring more than 160. The damage bill has been estimated at around A$4 billion dollars, including an insured loss of over A$1 billion. All the result of just a few seconds of earthquake ground shaking at 10:27am on 28 December 1989 (McCue and others, 1990). The consequences of this moderate earthquake to Newcastle (Pop. 300 000), an industrial city on Australia's east coast, could so easily have been avoided with the hindsight of history and the application of relatively inexpensive earthquake engineering principles.

The Mw 7.1 New Zealand earthquake was the largest earthquake in New Zealand in 60 years and occurred in the sparsely populated Fiordland region of New Zealand. The earthquake caused no deaths and only minor damage in the town of Te Anau, although it was felt through out most of the south island of New Zealand. Surprisingly, it was felt in Sydney, 1800 kilometre away, with some people evacuating buildings. People in Sydney did not feel body or surface waves but felt the T phase from the event. Human perception of a T phase is very rare, with the 1977 Mw8.1 Tonga event being felt in Tahiti 2600 km away (Talandier and Okal 1979), being one of the few well documented instances. The Sydney recording of T phase, whilst larger than the body waves, would still be considered weak motion and not normally felt. I suggest that for someone to have felt this event required the coincident of several factors which enhanced the resulting shaking.

This poster shows earthquakes occurring in Australia in 2011 with a background of earthquakes occurring in Australia over the past 10 years. Also included are images produced as part of the analysis of the Bowen Earthquake and its associated aftershocks as well as the yearly summary of earthquake occurrences in Australia.

Legacy product - no abstract available

Probabilistic seismic-hazard analyses (PSHAs) require an estimate of Mmax, the magnitude (M) of the largest earthquake that is thought possible within a specified area. In seismically active areas such as some plate boundaries, large earthquakes occur frequently enough that Mmax might have been observed directly during historic times. In less active regions like Australia, and most of the Central and Eastern United States and adjacent Canada (CEUSAC), large earthquakes are much less frequent and generally Mmax must be estimated indirectly. By virtue of a fortuitous combination of climatic conditions, geology and geomorphology, Australia boasts arguably the richest Quaternary faulting record of all the world's SCR crust. Extensive consultation amongst the geological 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 across Australia. Variations in the character of these scarps, when considered together with large-scale geological and geophysical variations, justify the division of the continent into six onshore 'neotectonic domains'. Within each domain, mean Mmax has been calculated from the 75th percentile scarp length by averaging the earthquake magnitudes predicted by several published relations. Results range between M7.0-7.5±0.2. While this approach is inherently conservative, extreme values relating to multiple event scarps, which cannot be confidently discriminated without field validation, are removed. Consequently, in several cases our data represent an underestimate of 0.1-0.2 magnitude units relative to calculations based upon rare palaeoseismic data. Nevertheless, our findings indicate the potential for M>7.0 earthquakes across Australia, and by proxy analogous crust in the CEUSAC and elsewhere, and thereby have the potential to significantly reduce uncertainty in PSHAs.

In an unpublished report Taylor (1955) suggested that both tectonic earthquakes and volcanic activity are related to prevailing conditions of regional stress. The diagnostic value of this relationship lies in the fact that abnormal stress conditions make their presence known first by tectonic earthquakes and later by volcanic eruption. This theory was developed as a result of intensive research following upon study of the new Hebrides volcanic arc and recent volcanism. Bougainville Island, with a deep trough (Planet Deep) situated west of and orientated parallel to its line of volcanoes, exhibits a similar structural pattern to the New Mebride4s Islands and it was considered by Taylor that the relationship between tectonic earthquakes and volcanic eruptions might also apply here. As a possible means of diagnosis an analysis of earthquakes and volcanic activity in the Bougainville area was undertaken to discover whether a positive relationship existed fro Mt. Bagana, and if so, whether there were indications of impending eruption of the Lake Loloru Crater.

Earthquakes are a threat to life and property in Australia as demonstrated by the 1989 Newcastle earthquake (McCue & others, 1990). This report contains information on earthquakes of Richter magnitude 3 or greater reported in the Australian region during 1992. It is the thirteenth of an annual series compiled by the Australian Geological Survey Organisation (AGSO), using data from AGS0 and contributing 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; Accelerograph data; Principle world earthquakes; and Monitoring of nuclear explosions.