stress orientations and active fault kinematics of the vienna basin fault system, austria
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AIM Annual Meeting, Bratislava, 29-30.09.2010
Stress orientations and active fault kinematics of the Vienna Basin Fault System, Austria
K. Decker (1), G. Burmester (2) & W. Lenhardt (3)
(1) University Vienna (2) Fronterra Geosciences, Vienna, Austria(3) ZAMG Vienna
AIM Annual Meeting, Bratislava, 29-30.09.2010
Introduction
Local setting and fault kinematics
Active tectonics
2D and 3D geometry of active faults of the Vienna Basin Fault System Seismicity, FPS and aktive fault kinematics
Stress orientations
Stress data (SH) from high-quality FMI and caliper analyses SH orientation and evidence for stress partitioning at active faults
Conclusions
Outline
AIM Annual Meeting, Bratislava, 29-30.09.2010
Active faults in the Vienna Basin
NE-striking strike-slip fault at the SE margin of the Miocene
pull-apart
Moderate seismicity
N-striking normal splay faults branching off the strike-slip
system
No historical seismicity
AIM Annual Meeting, Bratislava, 29-30.09.2010
Decker et al. 2005, QSRHinsch et al. 2005, QSR
Hinsch & Decker 2004, Terra NovaSalcher et al. submitted, Basin Research
Data Background
AIM Annual Meeting, Bratislava, 29-30.09.2010
Segment boundaries defined by fault bends and branchlines of major normal faults
„Rough“ strike-slip fault with marked changes of fault strike at depth
Strike-Slip Fault Kinematics
Most of the extension at releasing bends is transferred to normal faults
Normal faults are linked to the strike-slip system via a common detachment
AIM Annual Meeting, Bratislava, 29-30.09.2010
Most of the extension at releasing bends is transferred to normal faults
Normal faults are linked to the strike-slip system via a common detachment
Normal Branch Faults
Segment boundaries defined by fault bends and branchlines of major normal faults
„Rough“ strike-slip fault with marked changes of fault strike at depth
AIM Annual Meeting, Bratislava, 29-30.09.2010
3D fault geomoetry
AIM Annual Meeting, Bratislava, 29-30.09.2010
Quaternary fault map
Quaternary faults
ZAMG 2008
NE-striking seismic strike-slip fault at the SE margin of the
Miocene pull-apart basin
Section 1
N-striking normal splay faults branching off the strike-slip
system
Section 2
Section 3
Section 3
AIM Annual Meeting, Bratislava, 29-30.09.2010
Decker et al., QSR 2005
230 prel.250 prel.242 ± 29
208 ± 23
232 ± 41261 ± 32 295 ± 32
259 ± 26278 ± 29284 ± 28292 ± 35
OSL ages (Feldspar)J. LOMAX
Normal Branch Faults
AIM Annual Meeting, Bratislava, 29-30.09.2010
Markgrafneusiedl Fault cutting the
Gänserndorf Terrace (250 ky) and overlying
loess (20 - 15 ky)
AIM Annual Meeting, Bratislava, 29-30.09.2010
Spatial fault data from Quaternary fault maps (surface) and 2D/3D seismic
Hölzel et al., Marine Petrol Geol. 2010Hölzel et al., AJES 2008
- 1 0 0 0
1 0 1 01 2 k m1 2 k m2 0 2 03 0 3 04 0 4 0
6 0 6 05 0 5 0
S t r e n g t h ( M p a )
V i e n n a B a s i nS t y r i a n B a s i nT a u e r n W i n d o w
G e n s e r e t a l . 1 9 9 6 S a c h s e n h o f e r1 9 9 6 L a n k r e i j e r( 1 9 9 8 )
Depth (km)
00 01 0 0 01 0 0 0 1 0 0 0
d r yw e t
L i t h o s p h e r i c s t r e n g t h m o d e l l i n g
2 00 4 0 6 0N o . o f e v e n t s
F o c a l d e p t h s o f e a r t h q u a k e s
- 1 0 0 0
1 0 1 01 2 k m1 2 k m2 0 2 03 0 3 04 0 4 0
6 0 6 05 0 5 0
S t r e n g t h ( M p a )
V i e n n a B a s i nS t y r i a n B a s i nT a u e r n W i n d o w
G e n s e r e t a l . 1 9 9 6 S a c h s e n h o f e r1 9 9 6 L a n k r e i j e r( 1 9 9 8 )
Depth (km)
00 01 0 0 01 0 0 0 1 0 0 0
d r yw e t
L i t h o s p h e r i c s t r e n g t h m o d e l l i n g
2 00 4 0 6 0N o . o f e v e n t s
F o c a l d e p t h s o f e a r t h q u a k e s
Faults root in the Alpine-Carpathian floor thrust Hypocenter depths < 12 km (90 % of events)
3D fault geomoetry
AIM Annual Meeting, Bratislava, 29-30.09.2010
Quaternary faults
ZAMG 2008
NE-striking seismic strike-slip fault at the SE margin of the
Miocene pull-apart basin
N-striking normal splay faults branching off the strike-slip
system
Seísmicity and active fault kinematics
AIM Annual Meeting, Bratislava, 29-30.09.2010
Mostly N to NNW-trending P-axes
Strike-slip >> Normal faulting
Few but reliable contradicting data (blue beachballs)
FPS and fault kinematics
AIM Annual Meeting, Bratislava, 29-30.09.2010
FPS and fault kinematics
Preferred nodal plane highlights N to NE-striking sinistral faults
In line with makroseimick data (orientation of inner isoseismals)
Few contradicting data (blue beachballs)
AIM Annual Meeting, Bratislava, 29-30.09.2010
Borehole breakout on opposing sides of the borehole wall (180°)
Induced tensile fractures 90° to borehole breakout, inclined and often with stair stepping appearance
Induced centerline fractures 90° to borehole breakout, vertical
Stress data (SH orientations)
FMI examples: breakouts and induced tensile fractures
FMI Acoustic Acoustic traveltime
AIM Annual Meeting, Bratislava, 29-30.09.2010
FMI Acoustic FMI Acoustic
Stress data (SH)FMI examples
Induced tensile fractures 90° to borehole breakout, inclined and often with stair stepping appearance
Borehole breakout on opposing sides of the borehole wall (180°)
AIM Annual Meeting, Bratislava, 29-30.09.2010
Stress data (SH orientations)
Most data indicate N to NNW-oriented SH
Significant stress changes occur at normal faults slplaying from the sinistral wrench fault
AIM Annual Meeting, Bratislava, 29-30.09.2010
Stress data (SHmax orientations)
Significant stress change of ~ 40° at faults such as Steinberg Fault
Marsch et al., 1990: Decker et al., 2005
AIM Annual Meeting, Bratislava, 29-30.09.2010
Conclusions
Both FPS and stress data are consistent with geological / geodetic evidence for sinistral strike-slip faulting
Stress partitioning occurs at active faults delimiting the wrench zone to the NW
AIM Annual Meeting, Bratislava, 29-30.09.2010
Stress partitioning occurs at active faults delimiting the wrench zone to the NW
Thanks to OMV Austria (C. Astl, G. Arzmüller, H. Peresson)
Conclusions
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