Tectonics, In Situ Stress Stress, Faults and Rock Failure · Hori, M. and S. Nemat-Nasser,...
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Tectonics, In Situ Stress Stress, Faults and Rock Failure Thomas Doe Bill Dershowitz
Transcript of Tectonics, In Situ Stress Stress, Faults and Rock Failure · Hori, M. and S. Nemat-Nasser,...
Tectonics, In Situ Stress Stress, Faults and Rock Failure
Thomas DoeBill Dershowitz
Rocky Mountain Arsenal
Hori, M. and S. Nemat-Nasser, "Interacting Micro-Cracks Near the Tip in the Process Zone of a Macro-Crack," Journal of the Mechanics and Physics of Solids, Vol. 35, No. 5 (1987) 601-629.
Mohr Circles and Faults
J.C. Jaeger, NGW Cook, and RW Zimmerman, Fundamentals of Rock Mechanics, Blackwell, Fourth edition, 2007
Pore Pressure: Rocky Mountain Arsenal
Tectonic Plates
Evolution of Spreading Sea Floor —Atlantic Analog
Subduction Zone – Island Arc
http://www-wsm.physik.uni-karlsruhe.de/pub/introduction/introduction_frame.html
World Stress Map
North America Stresses
Pacific Northwest Tectonics
HOLOCENE FAULT SCARPS AND SHALLOW MAGNETIC ANOMALIES ALONG THE SOUTHERN WHIDBEY ISLAND FAULT ZONE NEAR WOODINVILLE, WASHINGTON By Brian L. Sherrod, Richard J. Blakely, Craig Weaver, Harvey Kelsey, Elizabeth Barnett, and Ray Wells USGSOpen-File Report 2005-1136 March 2005
Mohr Circles and Faults
J.C. Jaeger, NGW Cook, and RW Zimmerman, Fundamentals of Rock Mechanics, Blackwell, Fourth edition, 2007
Guri Venvik Ganerød a,b,*, Alvar Braathen b,c, Bjørn Willemoes-Wissing, Predictive permeability model of extensional faults in crystallineand metamorphic rocks; verification by pre-grouting in two sub-sea tunnels, Norway, Journal of Structural Geology 30 (2008) 993–1004
Guri Venvik Ganerød a,b,*, Alvar Braathen b,c, Bjørn Willemoes-Wissing, Predictive permeability model of extensional faults in crystallineand metamorphic rocks; verification by pre-grouting in two sub-sea tunnels, Norway, Journal of Structural Geology 30 (2008) 993–1004
Guri Venvik Ganerød a,b,*, Alvar Braathen b,c, Bjørn Willemoes-Wissing, Predictive permeability model of extensional faults in crystallineand metamorphic rocks; verification by pre-grouting in two sub-sea tunnels, Norway, Journal of Structural Geology 30 (2008) 993–1004
Further Illustrations of Stereonets
Critically Stressed FracturesSeismic Focal Mechanisms
Critically Stressed Fractures
Mark Zoback, Reservoir Geomechanics, Cambridge, 2007
Earthquake on a vertical plane
Edited from Cox and Hart. Plate Tectonics – How it works.
nctr.pmel.noaa.gov/education/ITTI/seismic/Focal_mech_USGS.ppt
Presenter
Presentation Notes
Most earthquakes are double couple, in this situation the first motions are more complex. If we consider a strike slip earthquake on a vertical fault, then the ground motion can be divided into 4 quadrants - 2 with compression and 2 with dilation. The divisions between the compression and dilation are called the “nodal planes”.
Earthquake Planes
USGS
nctr.pmel.noaa.gov/education/ITTI/seismic/Focal_mech_USGS.ppt
Presenter
Presentation Notes
These are examples of the simple cases of strike-slip and pure dip-slip (normal and thrust) motion on a fault. The upper images show block diagrams illustrating the fault motion and the lower images the corresponding fault plane solution. These are the types of diagrams that will be explained during this session.
With a lot of recordings we can reconstruct faults with any orientations
Cox and Hart. Plate Tectonics – How it works.nctr.pmel.noaa.gov/education/ITTI/seismic/Focal_mech_USGS.ppt
Presenter
Presentation Notes
With enough stations the sphere around the focus will define regions of dilation and compression that define the two nodal planes. This sphere is then represented as the focal mechanism diagram using the stereographic projection.
Example Focal mechanism diagrams on mid-ocean ridges
Stein and Wysession, An Introduction to seismology, earthquakes and Earth structurenctr.pmel.noaa.gov/education/ITTI/seismic/Focal_mech_USGS.ppt
Presenter
Presentation Notes
With real earthquakes the slip might be oblique, combining strike-slip with dip-slip, then we see a bechball that is a combination of the two.
Same N-S fault, different slip direction
Stein and Wysession, An Introduction to seismology, earthquakes and Earth structurenctr.pmel.noaa.gov/education/ITTI/seismic/Focal_mech_USGS.ppt
Presenter
Presentation Notes
These diagrams show how the focal mechanism solution changes with different slip direction on the same north-south fault.
Samuel Y. Johnson, Christopher J. Potter, John J. Miller, John M. Armentrout, Carol Finn and Craig S. WeaverThe southern Whidbey Island fault: An active structure in the Puget Lowland, Washington, Geological Society of America Bulletin 1996;108;334-354
Liquefaction Features, Whidbey Island
Samuel Y. Johnson, Christopher J. Potter, John J. Miller, John M. Armentrout, Carol Finn and Craig S. WeaverThe southern Whidbey Island fault: An active structure in the Puget Lowland, Washington, Geological Society of America Bulletin 1996;108;334-354
