Newberg fault (Class A) No. 717
Last Review Date: 2016-03-22
citation for this record: Personius, S.F., compiler, 2002, Fault number 717, Newberg fault, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 05/07/2024 05:37 PM.
| Synopsis |
The Newberg fault is part of the Gales Creek-Mount Angel structural zone, a northwest-striking zone of dextral-reverse faults that has been active at least since the Miocene when they controlled the emplacement of Miocene Columbia River Basalt Group lava flows in the northern Willamette Valley. The fault primarily is mapped in the subsurface on the basis of water well, aeromagnetic, and gravity data. No unequivocal evidence of displacement in Quaternary deposits has been described, but most of the fault trace is covered by a thick sequence of silty sediment deposited by the Missoula floods which may have buried evidence of pre-latest Quaternary displacement. |
| Name comments |
The Newberg fault was mapped on the basis of water well data and named by Werner (1990 #3946) after the town of Newberg in the northern Willamette Valley; this fault is included in the Gales Creek-Mount Angel structural zone of Beeson and others (1985 #4022; 1989 #4023). Fault ID: This is fault number 30 of Geomatrix Consultants, Inc. (1995 #3593) and part of fault number 6 of Pezzopane (1993 #3544). |
| County(s) and State(s) |
YAMHILL COUNTY, OREGON |
| Physiographic province(s) |
PACIFIC BORDER |
| Reliability of location |
Good Compiled at 1:100,000 scale. Comments: The fault trace is from 1:100,000-scale compilation of Yeats and others (1996 #4291).
|
| Geologic setting |
The Newberg fault is part of the Gales Creek-Mount Angel structural zone, a northwest-striking zone of dextral-reverse faults that has been active at least since the Miocene when they controlled the emplacement of Miocene Columbia River Basalt Group lava flows in the northern Willamette Valley (Beeson and others, 1985 #4022; 1989 #4023). The fault primarily is mapped in the subsurface on the basis of water well, aeromagnetic, and gravity data (Werner, 1990 #3946; Yeats and others, 1991 #3953; 1996 #4291; Blakely and others, 2000 #4333).
|
| Length (km) | 5 km. |
| Average strike | N42°W |
| Sense of movement |
Right lateral, Reverse
Comments: The fault is part of the Gales Creek-Mount Angel structural zone, a dextral-reverse fault zone (Beeson and others, 1985 #4022; 1989 #4023).
|
| Dip Direction | Unknown |
| Paleoseismology studies |
|
| Geomorphic expression |
No fault scarps on Quaternary deposits have been described anywhere along the Newberg fault (Geomatrix Consultants Inc., 1995 #3593). However, S.K. Pezzopane (pers. commun., 1993, in Geomatrix Consultants Inc., 1995 #3593) describes lineaments in fluvial terraces and bedrock notches along a northwest trend to the east of Newberg, based on reconnaissance of small-scale (1:20,000 to 1:60,000) aerial photography. Unruh and others (1994 #3597) conducted the most comprehensive study of possible Quaternary activity on the Newberg fault; they examined large-scale (1:12,000) aerial photography, and conducted aerial and field reconnaissance along the trace of the fault. Unruh and others (1994 #3597) found no geomorphic evidence of faulting, and mapped the structure as Tertiary in age. Most of the fault trace is covered by a thick sequence of silty sediment deposited by the Missoula floods (O'Connor and others, 2001 #5121) which may have buried evidence of pre-latest Quaternary displacement.
|
| Age of faulted surficial deposits | No unequivocal evidence of displacement in Quaternary deposits has been described (Geomatrix Consultants Inc., 1995 #3593). |
| Historic earthquake | |
| Most recent prehistoric deformation |
undifferentiated Quaternary (<1.6 Ma)
Comments: Unruh and others (1994 #3597) found no geomorphic evidence of faulting, and mapped the structure as Tertiary in age. Pezzopane (1993 #3544) mapped the fault as active in the Quaternary (<1.8 Ma). Geomatrix Consultants, Inc. (1995 #3593) and Madin and Mabey (1996 #3575) compiled these faults as active in the middle and late Quaternary (<780 ka), based on similar trend and possible connection to the Mount Angel fault [873]. Given the equivocal evidence of Quaternary displacement, the Newberg fault is herein classified as Quaternary (<1.6 Ma) until further studies are conducted.
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| Recurrence interval | |
| Slip-rate category |
Less than 0.2 mm/yr
Comments: No detailed slip rate data have been published. Geomatrix Consultants, Inc. (1995 #3593) assigned slip rates of 0.005–0.01 mm/ yr and Wong and others (1999 #4073; 2000 #5137) assigned rates of 0.1–0.4 mm/yr to the Newberg fault. Given the lack of evidence of displacement in Quaternary deposits, low rates of slip are assumed. |
| Date and Compiler(s) |
2002
Stephen F. Personius, U.S. Geological Survey |
| References |
#4022 Beeson, M.H., Fecht, K.R., Reidel, S.P., and Tolan, T.L., 1985, Regional correlations within the Frenchman Springs member of the Columbia River Basalt Group—New insights into the middle Miocene tectonics of northwestern Oregon: Oregon Geology, v. 47, no. 8, p. 87-96. #4023 Beeson, M.H., Tolan, T.L., and Anderson, J.L., 1989, The Columbia River Basalt Group in western Oregon-Geologic structures and other factors that controlled flow emplacement patterns, in Reidel, S.P., and Hooper, P.R., eds., Volcanism and tectonism in the Columbia River Flood-Basalt Province: Geological Society of America Special Paper 239, p. 223-246. #4333 Blakely, R.J., Wells, R.E., Tolan, T.L., Beeson, M.H., Trehu, A.M., and Liberty, L.M., 2000, New aeromagnetic data reveal large strike-slip (?) faults in the northern Willamette Valley, Oregon: Geological Society of America Bulletin, v. 112, p. 1225-1233. #3593 Geomatrix Consultants, Inc., 1995, Seismic design mapping, State of Oregon: Technical report to Oregon Department of Transportation, Salem, Oregon, under Contract 11688, January 1995, unpaginated, 5 pls., scale 1:1,250,000. #3575 Madin, I.P., and Mabey, M.A., 1996, Earthquake hazard maps for Oregon: State of Oregon, Department of Geology and Mineral Industries Geological Map Series GMS-100, 1 sheet. #5121 O'Connor, J.E., Sarna-Wojcicki, A.M., Wozniak, K.C., Polette, D.J., and Fleck, R.J., 2001, Origin, extent, and thickness of Quaternary geologic units in the Willamette Valley, Oregon: U.S. Geological Survey Professional Paper 1620, 52 p., 1 pl., scale 1:250,000. #3544 Pezzopane, S.K., 1993, Active faults and earthquake ground motions in Oregon: Eugene, Oregon, University of Oregon, unpublished Ph.D. dissertation, 208 p. #3597 Unruh, J.R., Wong, I.G., Bott, J.D.J., Silva, W.J., and Lettis, W.R., 1994, Seismotectonic evaluation, Scoggins Dam, Tualatin Project, northwestern Oregon: Final Report prepared for U.S. Department of the Interior, Bureau of Reclamation, 206 p., 4 pls., scale 1:500,000. #3946 Werner, K.S., 1990, I. Direction of maximum horizontal compression in western Oregon determined by borehole breakouts II. Structure and tectonics of the northern Willamette Valley, Oregon: Oregon State University, unpublished M.S. thesis, 159 p., 5 pls., scale 1:100,000. #4073 Wong, I., Silva, W., Bott, J., Wright, D., Thomas, P., Gregor, N., Li, S., Mabey, M., Sojourner, A., and Wang, Y., 1999, Earthquake scenario and probabilistic ground shaking maps for the Portland, Oregon metropolitan area: Technical report to U.S. Geological Survey, under Contract 1434-HQ-96-GR-02727, 16 p., 12 pls. #5137 Wong, I., Silva, W., Bott, J., Wright, D., Thomas, P., Gregor, N., Li, S., Mabey, M., Sojourner, A., and Wang, Y., 2000, Earthquake scenario and probabilistic ground shaking maps for the Portland, Oregon, metropolitan area: State of Oregon, Department of Geology and Mineral Industries Interpretive Map Series IMS-16, 16 p. pamphlet, scale 1:62,500. #3953 Yeats, R.S., Graven, E.P., Werner, K.S., Goldfinger, C., and Popowski, T., 1991, Tectonics of the Willamette Valley, Oregon: U.S. Geological Survey Open-File Report 91-441-P, 47 p., 3 pls. #4291 Yeats, R.S., Graven, E.P., Werner, K.S., Goldfinger, C., and Popowski, T.A., 1996, Tectonics of the Willamette Valley, Oregon, in Rogers, A.M., Walsh, T.J., Kockelman, W.J., and Priest, G.R., eds., Assessing earthquake hazards and reducing risk in the Pacific Northwest: U.S. Geological Survey Professional Paper 1560, v. 1, p. 183-222. |