Lec.25.pptx - 11/21/11 25. Faults (II) •  Slip...

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Unformatted text preview: 11/21/11 25. Faults (II) •  Slip along Faults •  Structure along faults –  Strike ­slip faul;ng –  Dip ­slip faul;ng •  Normal Faul;ng •  Reverse Faul;ng –  Oblique slip faul;ng –  Echelon paGerns –  Tail cracks –  Slickenlines •  Structure across faults –  Fractures –  Deforma;on bands •  How do natural faults form? –  Faulted Joints –  Faulted Dikes 11/21/11 GG303 1 Strike ­slip Faults 11/21/11 GG303 2 1 11/21/11 San Andreas Fault, CA Carrizo Plain hGp://en.wikipedia.org/wiki/File:San_Andreas_Fault_Aerial_View.gif 11/21/11 GG303 3 Offset of rows in plowed field 1979 Imperial Valley Earthquake hGp://www.smate.wwu.edu/teched/geology/eq ­faults.html 11/21/11 GG303 4 2 11/21/11 2.6 m fence offset 1906 San Francisco earthquake hGp://www.smate.wwu.edu/teched/geology/eq ­faults.html 11/21/11 GG303 5 Dip ­slip Faults: Normal Faults 11/21/11 abbasimehr.ir GG303 6 3 11/21/11 Faceted Spurs Deep Springs, CA 11/21/11 piG.edu GG303 7 Halemaumau sa[tp.soest.hawaii.edu 11/21/11 GG303 8 4 11/21/11 Kilauea Caldera 11/21/11 ged.rwth ­aachen.de GG303 9 Kilauea Caldera 11/21/11 rst.gsfc.nasa.gov GG303 10 5 11/21/11 Horsts and Grabens Rima Ariadaeus, Moon hGp://en.wikipedia.org/wiki/File:Fault ­Horst ­Graben.svg hGp://en.wikipedia.org/wiki/File:As10 ­31 ­4646.jpg 11/21/11 GG303 11 Dip ­slip Faults: Reverse Faults Reverse Fault, Himalaya From Grasemann et al., 2005 11/21/11 GG303 12 6 11/21/11 Oblique ­slip Faul;ng Pleasant Valley, Nevada, 1915 (M= 7.7) hGp://www.smate.wwu.edu/teched/geology/GeoHaz/eq ­faults/eq ­faults ­16.JPG 11/21/11 GG303 13 Structure Along Faults 11/21/11 GG303 14 7 11/21/11 Echelon fractures along Imperial Fault 1979 Imperial Valley Earthquake hGp://www.smate.wwu.edu/teched/geology/eq ­faults.html 11/21/11 GG303 15 MoleTrack, with Echelon Ridges 1976 Guatamala Earthquake 11/21/11 yuprocks.com GG303 16 8 11/21/11 Echelon Segments 2010 Christchurch Earthquake flutrackers.com 11/21/11 GG303 17 Echelon fractures in fault ­parallel bands Sierra Nevada, CA 11/21/11 GG303 18 9 11/21/11 Right step between two leP ­lateral fault segments, Sierra Nevada, CA 11/21/11 GG303 19 FoliaQon along fault, Sierra Nevada, CA 11/21/11 GG303 20 10 11/21/11 AlteraQon along fault, Sierra Nevada, CA 11/21/11 GG303 21 Fractures linking leP ­lateral faults, Sierra Nevada, CA 11/21/11 GG303 22 11 11/21/11 Tail cracks at the end of a fault trace Sierra Nevada, CA 11/21/11 GG303 23 Tail cracks at the end of a fault trace Grimsel Underground Laboratory 11/21/11 GG303 24 12 11/21/11 A mechanical explana;on for echelon structure along strike ­slip faults From Martel and Boger, 1998 11/21/11 GG303 25 Slickenlines, Sierra Nevada, CA 11/21/11 GG303 26 13 11/21/11 Structure Across Faults 11/21/11 GG303 27 Fractures in putaQve fault zone, Sierra Nevada, CA 11/21/11 GG303 28 14 11/21/11 Faults in Trench Exposures 11/21/11 murbachgeotech.com GG303 29 Fault Trench Log Hayward Fault, CA 11/21/11 geomaps.wr.usgs.gov GG303 30 15 11/21/11 Trench Log, San Andreas Fault, Pallet Creek, California hGp://3dparks.wr.usgs.gov/pp1515/chapter4/fig4 ­19.jpg 11/21/11 GG303 31 DeformaQon along a fault, Homestake Mine, South Dakota 11/21/11 GG303 32 16 11/21/11 Fault in a tunnel, Grimsel Underground Rock Laboratory, Switzerland 11/21/11 GG303 33 Deforma;on Bands, Utah 11/21/11 GG303 34 17 11/21/11 Deforma;on Bands, Utah 11/21/11 GG303 35 How Do Real Faults Form? hGp://www.geology.cwu.edu/facstaff/charlier/courses/g360/graphics/nor_fault.jpg hGp://courses.eas.ualberta.ca/eas421/diagramspublic/Mohrstressdiag.gif 11/21/11 GG303 36 18 11/21/11 How Do Real Faults with Nearly ­ straight Segmented Traces Form? From Joints? 11/21/11 GG303 37 How Do Real Faults with Nearly ­ straight Segmented Traces Form? From Dikes? From d’Alessio and Martel, 2005 Fault zones Fault zone Dike Regional Joints Dike A C B E D Host rock Aplite Dike Fractu res Slickenlines F G Martel and d'Alessio Figure 5 Development of strike-slip faults from dikes, Sequoia National Park, California 11/21/11 GG303 38 19 ...
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This note was uploaded on 12/05/2011 for the course GEOLOGY 300 taught by Professor Stephenmartel during the Fall '11 term at University of Hawaii, Manoa.

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