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Pacific Northwest Geologic Mapping and Urban Hazards

Ray E. Wells

Research Geologist

U.S. Geological Survey
345 Middlefield Road MS-973
Menlo Park, CA 94025

Telephone- (650) 329-4933
Fax- (650) 329-5490
Email- rwells@usgs.gov

SPECIALTIES:

Geologic mapping, Pacific Northwest geology and tectonics, geology of the Cascadia forearc, crustal deformation and neotectonics of convergent margins, structure of subduction zones, paleomagnetism

CURRENT WORK:

Ray's current work includes

PUBLICATIONS:

Wells, R. E., 1979, Drake Peak, a structurally complex rhyolite center in southeastern Oregon: U.S. Geological Survey Professional Paper, P-1124E, p. E1-E16.

Wells, R. E., 1979, Geologic map of the Cape Disappointment-Naselle River area, Pacific County, Washington: U.S. Geological Survey Open-file Report 79-389, scale 1:48,000 (superceded by pub. 15).

Wells, R. E., 1981, Geologic map of the eastern Willapa Hills, Cowlitz, Lewis, Pacific, and Wahkiakum Counties, Washington: U.S. Geological Survey Open-file Report 81-674, (one oversize sheet with text), scale 1:62,500.

Magill, J., Wells, R. E., Simpson, R. W., and Cox, A. V., 1982, Post 12 m.y. rotations of southwestern Washington: Journal of Geophysical Research, v. 87, p. 3761-3776.

Wells, R. E., 1982, Paleomagnetism and geology of Eocene volcanic rocks in southwest Washington: Constraints on mechanisms of rotation and their regional tectonic significance: Ph.D dissertation, Univ. of California, Santa Cruz, 165 pp.

Wells, R. E., Niem, A. R., MacLeod, N. S., Snavely, P. D., Jr., and Niem, W. A., 1983, Preliminary geologic map of the west half of the Vancouver (WA-OR) 1° x 2° Quadrangle, Oregon: U.S. Geological Survey Open File Report 83-591, (oversize sheet with interpretative text), scale 1:250,000.

Wells, R. E., Engebretson, D. C., Snavely, P. D., Jr., and Coe, R. S., 1984, Cenozoic plate motions and the volcano-tectonic evolution of western Oregon and Washington: Tectonics, v. 3, p. 275-294 .

Snavely, P. D., Jr., and Wells, Ray E., 1984, Tertiary volcanic and intrusive rocks on the Oregon and Washington continental shelf: U.S. Geological Survey Open-File Report 84-282, 17 p.

Wells, R. E., and Coe, R. S., 1985, Paleomagnetism and geology of Eocene volcanic rocks of southwest Washington, implications for mechanisms of tectonic rotation: Journal of Geophysical Research, v. 90, p. 1925-1947

Wells, R. E., 1985, Review of Methods in rock magnetism and paleomagnetism. Techniques and instrumentation, by D. W. Collinson: Marine Geology, v. 65, p. 192-193.

Wells, R. E., 1984, Paleomagnetic constraints on the interpretation of early Cenozoic Pacific Northwest paleogeography, in Nilsen, Tor H., ed., Geology of Upper Cretaceous Hornbrook Formation, Oregon and California: Pacific Section S.E.P.M., v. 42, p. 231-237.

Beck, M. E., Jr., Burmester, R. F., Craig, D. G., Gromme, C. S., and Wells, R. E., 1986, Paleomagnetism of middle Tertiary volcanic rocks from the Western Cascade Series, northern California: timing and scale of rotation in the southern Cascades and Klamath Mountains: Journal of Geophysical Research, v. 91, p. 8219-8230.

Gromme, C. S., Beck, M. E., Jr., Wells, R. E., and Engebretson, D. C., 1986, Paleomagnetism of the Tertiary Clarno Formation and its significance for the tectonic history of the Pacific Northwest: Journal of Geophysical Research, v. 19, p. 14,089-14,104.

Wells, R. E., and Heller, P. L., 1988, The relative contribution of accretion, shear, and extension to Cenozoic tectonic rotations in the Pacific Northwest: Geological Society of America Bulletin, v. 100, p. 324-338.

Wells, R. E., 1989, Geologic map of the Cape Disappointment-Naselle River area, Pacific and Wahkiakum Counties, Washington: U.S. Geological Survey Miscellaneous Investigations Map I-1832; one oversize sheet with interpretive explanation, scale 1:62,500; supercedes OF79-389.

Wells, R. E., 1989, Mechanisms of Cenozoic tectonic rotation, Pacific Northwest convergent margin, U.S.A.: in Kiessel, C. and Laj, C., Paleomagnetic rotations and continental deformation, NATO Advanced Study Institute v. C254, p. 313-325, Kluwer Publishers, Netherlands.

Wells. R. E., Simpson, R. W., Bentley, R. D., Beeson, M. H., Mangan, M. T., and Wright, T. L., 1989, Correlation of Miocene flows of the Columbia River Basalt Group from the central Columbia River Plateau to the coast of Oregon and Washington: in Hooper, P., and Reidel, S., eds., Volcanism and tectonism in the Columbia River flood basalt province, Geological Society of America Special Paper 239, p. 113-130.

Wells, R. E., 1989, Paleomagnetic rotations and the Cenozoic tectonics of the Cascade arc, Washington, Oregon, and California: in Muffler, L.P.J., Blackwell, D. D., and Weaver, C. A., eds., Geological, Geophysical and Tectonic setting of the Cascade Range: U.S. Geological Survey Open-File Report 89-178 (Red Book) p. 1-16.

Wells, R. E., and Hillhouse, J. W., 1989, Paleomagnetism and tectonic rotation of the lower Miocene Peach Springs Tuff - Colorado Plateau, Arizona: to Barstow, California: Geological Society of America Bulletin, v. 101, p. 846-863

Wells, R. E., 1989, Origin of the oceanic basalt basement of the Solomon Islands arc and its relationship to the Ontong Java Plateau--Insights from Cenozoic plate motion models: Tectonophysics, v. 165, p. 219-235; (reprinted in Vedder, J. G. and Bruns, T. R., eds., 1989, Geology and offshore resources of Pacific island arcs - Solomon Islands and Bouganville, Papua New Guinea Regions: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources Earth Science Series, v. 12, p. 7-22).

U.S. Geological Survey, 1989, Preliminary map of fractures formed in the Summit Road-Skyland Ridge area during the Loma Prieta, California earthquake of October 17, 1989: U.S. Geological Survey Open File Map 89-686. 1 Sheet, scale 1:12,000

Plafker, G. and Galloway, J. P., and 31 contributors, 1989, Lessons learned from the Loma Prieta, California earthquake of October 17, 1989: U.S. Geological Survey Circular 1045, 48p.

U.S. Geological Survey, 1990, Loma Prieta California Earthquake: An anticipated event. Science, v. 247, p. 286-293.

Ponti, D., Wells, R. E., Haugerud, R. A., Clark, M. M., and Hall, N. T., 1990, Surface rupture aspects in: Lee Benuska, editor, Loma Prieta earthquake reconnaissance report: Earthquake Spectra: supplement to v. 6, p. 13-24

Ponti, D. J., and Wells, R. E., 1990, Extent and origin of surface fractures in the Summit Road-Skyland Ridge area; in Schwartz, D. P., and Ponti, D. J., eds., Field Guide to Neotectonics of the San Andreas Fault System, Santa Cruz Mountains, in light of the 1989 Loma Prieta Earthquake: U.S. Geological Survey Open File Report 90-274, p. 27-30

Wells, R. E., 1990, Paleomagnetic rotations and the Cenozoic tectonics of the Cascade Arc, Washington, Oregon, and California: Journal of Geophysical Research v. 95, p. 19,409-19,417.

Snavely, P. D., Jr., and Wells, R. E., 1991, Cenozoic evolution of the continental margin of Oregon and Washington: in Rogers, A. and others, editors, Earthquake Hazards in the Pacific Northwest of the United States: U.S. Geological Survey Open File Report 91-441B, 50p.

Hillhouse, J. W., and Wells, R. E., 1991, Magnetic fabric, flow directions, and source area of the lower Miocene Peach Springs Tuff in Arizona, California and Nevada: Journal of Geophysical Research, v. 96, p. 12,443-12,460.

England, P. C., and Wells, R. E., 1991, Neogene rotations and semi-continuous deformation of the Pacific Northwest continental margin: Geology, v. 19, p. 978-981

Ponti, D. and Wells, R. E., 1991, Off-fault ground rupture in the Santa Cruz Mountains, California: Ridge top spreading vs. tectonic extension during the Loma Prieta earthquake: Bulletin of the Seismological Society of America, v. 81, p. 1480-1510 and one oversize sheet, scale 1;36,000.

Snyder, S. L., Felger, T. J., Blakely, R. J., and Wells, R. E., 1993, Aeromagnetic map of the Portland-Vancouver metropolitan area, Oregon and Washington: U. S. Geological Survey Open-File Report 93-211, one oversize sheet, scale 1:100,000.

Snavely, P. D. Jr., Wells, R. E., and Minasian, Dianne, 1993, The Cenozoic geology of the Oregon and Washington Coast Range and Road Log for the Northwest Petroleum Association 9th annual field trip - Cenozoic geology of coastal northwest Oregon: U. S. Geological Survey Open-File Report 93-189, 40p.

Snavely, P. D. Jr., Bukry, David, and Wells, R. E., 1993, Coccolith-bearing late middle Eocene kerogen shale, Tillamook Highlands, northwest Oregon Coast Range: U. S. Geological Survey Open-File Report 93-623, 13p.

Wiley, T. J., Sherrod, D. R., Keefer, D. K., Qamar, Anthony, Schuster, R. L., Dewey, J. W., Mabey, M. A., Black, G. L., and Wells R. E., 1993, Klamath Falls earthquakes, September 20, 1993-including the strongest quake ever measured in Oregon: Oregon Geology, v. 55, p. 127-134.

Wells, R. E., and the Cascadia Working Group, 1993, CASCADIA, Regional Lithospheric Studies of the Pacific Northwest: U. S. Geological Survey Open-File Report 93-706, 39p.

Wells, R. E., Snavely, P. D. Jr., Macleod, N. S., Kelly, M. M., and Parker, M. J., 1994, Geologic map of the Tillamook Highlands, northwest Oregon Coast Range: U. S. Geological Survey Open-File Report 94-21, 23p. and two oversize sheets, scale 1:62,500.

Blakely, R. J., Wells, R. E., Yelin, T. S., Madin, I. P., and Beeson, M. H., 1995, Tectonic setting of the Portland-Vancouver area, Oregon and Washington: Constraints from low-altitude aeromagnetic data: Geological Society of America Bulletin, v. 107, p. 1051-1062.

on-line Wells, R. E., Snavely, P. D. Jr., Macleod, N. S., Kelly, M. M., Parker, M. J., Fenton, Johanna, and Felger, Tracey, 1995, Geologic map of the Tillamook Highlands, northwest Oregon Coast Range-a digital database: U. S. Geological Survey Open-File Report 95-670.

Blakely, R.J., Yelin, T.S., and Wells, R. E., 1996, Airborne hunt for faults in the Portland-Vancouver area: U.S. Geological Survey Fact Sheet 105-96, 2 p.

Niem, A. R., Wells, R. E., and Ryu, In-Chang 1996, Structural and stratigraphic plays; in: Ryu, In-Chang, Niem, A. R., and Niem, W. A., 1996, Oil and gas potential of the southern Tyee Basin, southern Oregon Coast Range: Oregon Department of Geology and Mineral Industries Oil and Gas Investigations No.19, p. 109-124.

Snavely, P. D., Jr., and Wells, R. E., 1996, Cenozoic evolution of the continental margin of Oregon and Washington: in Rogers, A. and others, editors, Earthquake Hazards in the Pacific Northwest of the United States: U. S. Geological Survey Professional Paper 1560, p. 161-182.

Blakely, R. J., Christiansen, R. L., Guffanti, Marianne, Wells, R. E., Donnely-Nolan, Julie, Muffler, L. J. P., Clynne, M. A., and Smith, J. G., 1997, Gravity anomalies, Quaternary vents, and Quaternary faults in the southern Cascade Range, Oregon and California: Implications for arc and backarc evolution: Journal of Geophysical Research, v. 102, p. 22,513-22,528.

Parsons, Tom, Trehu, A. M., Luetgert, J. H., Miller, Kate, Kilbride, F., Wells, R. E., Fisher, M. A., Flueh, Ernst, ten Brink, U. S., and Christiansen, N. I., 1998, A new view into the Cascadia subduction zone and volcanic arc: Implications for earthquake hazards along the Washington margin: Geology, v. 26, p. 199-202.

Jayko, A. S., Prentice, C. S., Rymer, M., and Wells, R. E., 1998, Scenic Drive landslide of January-March 1998, La Honda, San Mateo County, California: U. S. Geological Survey Open File Report OF98-229, 1 oversize sheet.

online imageWells, R. E., Weaver, C. S., and Blakely, R. J., 1998, Fore arc migration in Cascadia and its neotectonic significance; Geology, v. 26, p. 759-762, http://geology.geoscienceworld.org/cgi/content/abstract/26/8/759.

Parsons, Tom, Wells, R. E., Fisher, M. A., Flueh, Ernst, ten Brink, U. S., 1999, Three-dimensional velocity structure of Siletzia and other accreted terranes in the Cascadia fore arc of Washington: Journal of Geophysical Research, v. 104, p. 18,015-18,039.

Fisher, M. W., Flueh, E.R., Scholl, D.S., Parsons, Tom, Wells, R. E., Trehu, Anne, ten Brink, Uri, and Weaver, C.S., 1999, Geologic processes of accretion in the Cascadia subduction zone west of Washington state: Journal of Geodynamics, v. 27, p.277-288.

on-lineHaeussler, P., Yount, J. C., and Wells, R. E., 1999, Geologic Map of the Uncas 7.5' Quadrangle, Jefferson and Clallam Counties, Washington: U.S. Geological Survey Open File Report OF99-421, scale 1:24,000.

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.

on-lineBlakely, R.J., Wells, R. E., and Weaver, C.S., 1999, Puget Sound aeromagnetic maps and data, U.S. Geological Survey Open-File Report 99-514, http://geopubs.wr.usgs.gov/open-file/of99-514.

on-lineWells, R. E., Jayko, A., Niem, A. R., Black, G., Wiley, T., Baldwin, E., and Molenaar, K. M., Wheeler, K.L., Givler, R., and DuRoss, C., 2000, Geologic map and database of the Roseburg, Oregon 30' x 60' Quadrangle, Douglas and Coos Counties, Oregon: U.S. Geological Survey Miscellaneous Investigations Map and Open-File Report OF00-376, 2 sheets and 55 p. pamphlet, scale 1:100,000.

Pease, V., Hillhouse, J. W., and Wells, R. E., 2001, Paleomagnetic quantification of upper-plate deformation during Miocene detachment faulting in the Mohave Mountains, Arizona, Journal of Geophysical Research, submitted, 40 p.

online imageWells, R. E., and Simpson, R. W., 2001, Microplate motion of the Cascadia forearc and implications for subduction deformation; Earth Planets Space, v. 53, p. 275-283, http://www.terrapub.co.jp/journals/EPS/pdf/2001/5304/53040275.pdf.

Blakely, R.J., Wells, R. E., Weaver, C.S., and Johnson, S.Y., 2002, Location, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data: Geological Society of America Bulletin, v. 114, p. 169-177.

on-lineJayko, A. S., and Wells, R. E., 2001, Preliminary geologic map of the Dixonville 7.5' Quadrangle, Oregon: U. S. Geological Survey Open File Report OF01-0226, scale 1:24,000.

Brocher, T. M., Parsons, Tom., Blakely, R. J., Christiensen, N. I., Fisher, M. A., Wells, R. E., and the SHIPS Working Group, 2001, Upper Crustal structure in Puget Lowland, Washington: Results from the 1998 seismic hazards investigation in Puget Sound: Journal of Geophysical Research, v. 106, 13,541-13,564.

on-lineNelson, A.R., Johnson, S.Y., Wells, R. E., Pezzopane, S.K., Kelsey, H.M., Sherrod, B.L., Bradley, Lee-Ann, Koehler, Rick D. III, Bucknam, R.C., Haugerud, Ralph, and Laprade, W.T., 2002, Field and laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington: U.S. Geological Survey Open File Report OFR02-0060.

online imageWells, R.E., Blakely, R.J., Sugiyama, Y., Scholl, D.W., and Dinterman, P.A., 2003, Basin-centered asperities in great subduction zone earthquakes:  A link between slip, subsidence, and subduction erosion?  Journal of Geophysical Research, v. 108 (B10), 2507, doi:10.1029/2002JB002072, http://www.agu.org/journals/jb/jb0310/2002JB002072/.

Wells, R. E., and Vidale, J., 2000, Introduction, in Wells, R. E. and Vidale, J., eds., The Loma Prieta, California, Earthquake of October 17, 1989 - Geologic Setting and Crustal Structure: U.S. Geological Survey Professional Paper 1550-E, 11p.

on-lineGivler, R.W. and Wells, R. E., 2001, Shaded-Relief and Color Shaded-Relief Maps of the Willamette Valley, Oregon, U.S. Geological Survey Open-File Report 01-294, http://geopubs.wr.usgs.gov/open-file/of01-294/

Nelson, A.R., Johnson, S.Y., Wells, R. E., Kelsey, H.M., Pezzopane, S.K., Sherrod, B.L., 2002, Earthquake history of the Toe Jam Hill fault, Bainbridge Island, Washington: Geological Society of America Bulletin, in prep.

Peter J. Haeussler, Dwight C. Bradley, Ray E. Wells, Marti L. Miller, 2002, Life and death of the Resurrection Plate: evidence for an additional plate in the NE Pacific in Paleocene-Eocene time: Geological Society of America Bulletin, submitted.

online imageWells Ray E., R. J. Blakely, and C. S. Weaver, 2002, Cascadia microplate models and within-slab earthquakes: in Kirby, S., Wang, Kelin, and Dunlop, S., eds. Intraslab earthquakes in the Cascadia subduction system: Science and Hazards: US. Geological Survey Open File Report OF02-328, p. 17-24, http://geopubs.wr.usgs.gov/open-file/of02-328/.

Wells, Ray, 2006, Oregon geology--Parent of the soil, foundation for the vine: U.S. Geological Survey Open-File Report 2006-1069 [available on the World Wide Web at URL http://pubs.usgs.gov/of/2006/1069/ ].

onlineTabor, R.W., Haeussler, P.J., Haugerud, R.A., and Wells, R.E., 2011, Lidar-revised geologic map of the Uncas 7.5¹ quadrangle, Clallam and Jefferson Counties, Washington: U.S. Geological Survey Scientific Investigations Map 3160, 2 sheets, scale 1:24,000, pamphlet, 9 p., and GIS data [http://pubs.usgs.gov/sim/3160/].

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