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100 km wide zone, which could be accommodated by 10 faults
with slip rates consistent with the current topography and neotectonic faulting record (e.g.,
that half of the current relief of the Flinders Ranges, and a non-negligible proportion of
the relief in the Eastern Highlands (SESZ,
Figure 2.1
)
, might plausibly have been built
since the inception of the current stress regime. In contrast, similar seismogenic strain rates
activity in the SWSZ has increased dramatically in only the last 50 years (Michael-Leiba,
250 m/Ma across the
2.2.2 Seismogenic depth
subset of the Australian earthquake catalogue for detailed hypocentral depth analysis using
only depth values whose uncertainty was either less than the depth itself, or less than 5 km.
More than 75% of epicentres from the current earthquake catalogue are rejected using these
criteria. The selected data correlate with the regions of highest station density in the ANSN
(i.e., southern Australia).
The concentration of epicentres in the SWSZ (
Figure 2.1
)
occurs in non-extended
very shallow (see
Figure 2.3
)
, with 95% of events found to have occurred within the upper
earthquakes in the last five decades (
Figure 2.1
;
Table 2.1
)
. The largest of these earthquakes
(1968 Meckering;
Figure 2.1
- 9) is calculated to have initiated at 1.5 km depth and to
have ruptured both upwards to the surface and down to
Fredrich
et al
.,
1988
)
, while the smallest (2008 Katanning;
Figure 2.1
- 15) ruptured from
in the SWSZ (e.g., shallow depth) are typical of what might be expected throughout non-
extended cratonic crust in Australia. However, Australia's deepest known earthquakes are
also from this crustal setting: the 1989 Uluru earthquake (
Figure 2.3
- 1), with a calculated
Sea, north of the Northern Territory coastline (
Figure 2.3
- 2), which had a depth of 39 km