| Abstract: | The northern termination of the locked portion of the Hayward Fault near Berkeley, California, is found to coincide with the transition from strong Franciscan metagraywacke to melange on the western side of the fault. Both of these units are juxtaposed with various serpentinite, gabbro and graywacke units to the east, suggesting that the gouges formed within the Hayward Fault zone may vary widely due to the mixing of adjacent rock units and that the mechanical behavior of the fault would be best modeled by determining the frictional properties of mixtures of the principal rock types. To this end, room temperature, water-saturated, triaxial shearing tests were conducted on binary and ternary mixtures of fine-grained gouges prepared from serpentinite and gabbro from the Coast Range Ophiolite, a Great Valley Sequence graywacke, and three different Franciscan Complex metasedimentary rocks.
Friction coefficients ranged from 0.36 for the serpentinite to 0.84 for the gabbro, with four of the rock types having coefficients of friction ranging from 0.67-0.84. The friction coefficients of the mixtures can be predicted reliably by a simple weighted average of the end-member dry-weight percentages and strengths for all samples except those containing serpentinite. For the serpentinite mixtures, a linear trend between end-member values slightly overestimates the coefficients of friction in the midcomposition ranges. The range in strength for these rock admixtures suggests that both theoretical and numerical modeling of the fault should attempt to account for variations in rock and gouge properties. |
| Genre: | USGS Numbered Series |
| ProdID: | 98722 |
| Citation Author: | Morrow, Carolyn A.; Moore, Diane E.; Lockner, David A. |
| Citation Contributing Office: | Earthquake Hazards |
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| Citation Edition: | - |
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| Citation Language: | ENGLISH |
| Citation Larger Work Title: | |
| Citation LatN: | 0380600 |
| Citation LatS: | 0373000 |
| Citation LonE: | -1214800 |
| Citation LonW: | -1222400 |
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| Citation No Pagination: | N |
| Citation Number Of Pages: | |
| Citation Online Only Flag: | Y |
| Citation Phsyical Description: | iii, 17 p.; 2 Tables |
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| Citation Public Comments: | |
| Citation Publisher: | U.S. Geological Survey |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 2010-1184 |
| Citation Search Results Text: | Dependence of frictional strength on compositional variations of Hayward fault rock gouges; 2010; OFR; 2010-1184; Morrow, Carolyn A.; Moore, Diane E.; Lockner, David A. |
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| Citation Year: | 2010 |
| Type: | citation/reference |
| Text: | Dependence of frictional strength on compositional variations of Hayward fault rock gouges; 2010; OFR; 2010-1184; Morrow, Carolyn A.; Moore, Diane E.; Lockner, David A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/ofr_2010_1184.jpg |
| URL (INDEX PAGE): | http://pubs.usgs.gov/of/2010/1184/ |
| Date Other: | Wed, 22 Sep 2010 00:00 -0500 |
| Publisher: | U.S. Geological Survey |
