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Intraplate earthquakes in Australia
DAN CLARK, ANDREW MCPHERSON, AND T. ALLEN
Abstract
Relative to other intraplate areas of the world, Australia has a short recorded his-
tory of seismicity, spanning only a couple of centuries. As a consequence, there
is significant uncertainty as to whether patterns evident in the contemporary
seismic record are representative of the longer term, or constitute a bias result-
ing from the short sampling period. This problem can, in part, be overcome
by validation against Australia's rich record of morphogenic earthquakes -
Australia boasts arguably the richest late Neogene to Quaternary faulting record
of any stable continental region. Long-term patterns in large earthquake occur-
rence, both temporal and spatial, can be deduced from the landscape record
and used to inform contemporary earthquake hazard science. Seismicity source
parameters such as large earthquake recurrence and magnitude vary across the
Australian continent, and can be interpreted in a framework of large-scale neo-
tectonic domains defined on the basis of geology and crustal setting. Temporal
and spatial clustering of earthquakes is apparent at the scale of a single fault,
and at the 1,000 km scale of a domain. The utility of the domains approach,
which ties seismicity characteristics to crustal architecture and geology, is
that behaviours can be extrapolated from well-characterised regions to poorly
known analogous regions, both within Australia and worldwide.
2.1 Introduction
The Australian continent resides entirely within the Indo-Australian Plate, and is clas-
sified as a Stable Continental Region (SCR) in terms of its plate tectonic setting and
seismicity (Johnston et al ., 1994 ; Schulte and Mooney, 2005 ) . Such settings host approx-
imately 0.2% of the world's seismic moment release (Johnston, 1994 ) , and moderate to
large earthquakes are rare. Analysis of focal mechanisms from SCR crust (Zoback, 1992 ;
 
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