Quaternary Fault and Fold Database of the United States

As of January 12, 2017, the USGS maintains a limited number of metadata fields that characterize the Quaternary faults and folds of the United States. For the most up-to-date information, please refer to the interactive fault map.

Santa Monica fault (Class A) No. 101

Last Review Date: 2000-05-01

citation for this record: Treiman, J.A., and Bryant, W.A., compilers, 2000, Fault number 101, Santa Monica fault, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 05/11/2024 10:50 PM.

Synopsis	Onshore fault is identified in the subsurface (oil wells) and at the surface (geomorphology) (Wright, 1991 #5950; Dolan and others, 2000 #5964). Offshore fault is poorly known from limited marine geophysical lines (Junger and Wagner, 1977 #5945; Vedder and others, 1986 #5971). Late-Quaternary fault history is interpreted from one exposure (McGill, 1989 #5968) and one trenching site (site 101-1) (Dolan and others, 2000 #5964). Dolan and others (2000 #5964) reported 2–3 rupture events in the past 16–17 k.y. and at least 6 rupture events in the past 50 k.y. Dolan and others (1995 #5965) estimated a slip rate of 1.0–1.5 mm/yr and Dolan and others (2000 #5964) calculated a dip-slip rate of 0.5–0.6 mm/yr. Clark and others (1984 #2876) estimated a 0.27–0.30 mm/yr slip rate for the Potrero Canyon fault based on vertical separation only.
Name comments	Recognition of a fault zone in this vicinity was first published by Lawson and others (1908 #5925); Waring (1914 #5972) was the first to use the name "Santa Monica fault"; Hill (1928 #4959) described the "Santa Monica segment" of the "Anacapa Lineament", the lineament extending from south of San Miguel Island eastward to the Colorado River; Barbat (1958 #5953) described what he called the "Santa Monica fault system" coinciding roughly with the portion of the Anacapa lineament west of the San Andreas fault; Lang and Dreessen (1975 #5967) refer to the "Santa Monica zone of deformation". The western part of the fault was considered part of the Malibu Coast fault [99] by Lamar (1961 #5924), branching eastward into the Benedict Canyon fault and the Hollywood fault [102]. "Santa Monica fault" sometimes still includes the Hollywood fault [102] (e.g. Yerkes and others, 1965 #5930); however, the faults are described separately in this database. Sometimes referred to as north strand of the Santa Monica fault, along with a south strand, but south strand appears to be an older blind fault and has no surface expression (Dolan and Pratt, 1997 #5963; Pratt and others, 1998 #5969; Dolan and others, 2000 #5964). The first trace specifically mapped was at Potrero Canyon (Hoots, 1931 #5921) and was called "Potrero fault" by H.R. Johnson in 1932 and "Potrero Canyon fault" in 1959 by Moran and others (unpublished consulting reports cited by Hill, 1979 #5973); McGill (1989 #5968) recognized the Potrero Canyon fault as part of the Santa Monica fault. A surface trace (other than at Potrero Canyon) was not depicted until the work of Dolan and Sieh (1992 #5917). Fault extends westward from the "west Beverly Hills lineament" (Dolan and others, 2000 #5964) to Potrero Canyon and probably offshore to possible connection with Malibu Coast fault [99] and/or Anacapa-Dume fault [100]. Fault ID: Refers to numbers 390 (Malibu Coast offshore) and 391 (Santa Monica fault) of Jennings (1994 #2878) and number 80 (Santa Monica fault) of Ziony and Yerkes (1985 #5931).
County(s) and State(s)	LOS ANGELES COUNTY, CALIFORNIA
Physiographic province(s)	PACIFIC BORDER
Reliability of location	Good Compiled at 1:4,800; 1:80,000; 1:250,000; and 1:500,000 scale. Comments: Location of fault from Qt_flt_ver_3-0_Final_WGS84_polyline.shp (Bryant, W.A., written communication to K.Haller, August 15, 2017) attributed to 1;4,800-scale map by McGill (1989 #5968); 1:80,000-scale maps by Pratt and others (1998 #5969) and Dolan and others (2000 #5964); 1:250,000-scale map by Junger and Wagner (1977 #5945); and 1;500,000-scale map by Sorlien and others (2006 #7946).
Geologic setting	North-dipping, generally high-angle surface fault (shallower at depth) is part of east-west frontal fault system (also including Anacapa-Dume [100], Malibu Coast [99], Hollywood [102] and Raymond [103] faults) that has accommodated 80° of clockwise rotation of the western Transverse Ranges and perhaps as much as 60 km left slip displacement since early Miocene (Hornafius and others, 1986 #5922); modern activity is combination of continued strike-slip movement and compression (Dolan and others, 1995 #5965; Dolan and others, 2000 #5964).
Length (km)	35 km.
Average strike	N86°E
Sense of movement	Reverse Comments: Sense of movement reported by Dolan and others (2000 #5964); slickensides and other features indicate last movement at Potrero Canyon was reverse (Hill, 1979 #5973).
Dip	30°–70° N. Comments: Various dips are reported in the literature. A dip of approximately 45° is reported at Potrero Canyon (Hill, 1979 #5973); 30–35° ? in upper 300 m (Pratt and others, 1998 #5969) and 60–70° at depth (Tsutsumi and others, 1994 #5970); 40–45° in Sawtelle oil field (Wright, 1991 #5950).
Paleoseismology studies	Site 101-1, Veterans Hospital: Two trenches across 5-m-high scarp exposed faulted and deformed late-Pleistocene fan sediments and colluvial wedges attributed to late-Pleistocene and Holocene surface rupture/deformation events; 14C dating of deformed and undeformed sediment allowed interpretation of fault history, including at least 6 possible surface-rupturing events (Dolan and others, 2000 #5964).
Geomorphic expression	Subdued, left-stepping, 7- to 12-m-high, echelon scarps (fold scarps ?) across alluvial fans and Pleistocene terrace deposits and springs (Dolan and others, 2000 #5964).
Age of faulted surficial deposits	Latest-Pleistocene/Holocene paleosols (Dolan and others, 2000 #5964); late-Pleistocene alluvial fans, marine (stage 5e) and overlying non-marine terrace deposits (McGill, 1989 #5968; Dolan and others, 2000 #5964).
Historic earthquake
Most recent prehistoric deformation	latest Quaternary (<15 ka) Comments: The most recent event probably occurred between 1 and 3 ka and an earlier event occurred 10–7 k.y. ago (Dolan and others, 2000 #5964).
Recurrence interval	7–8 k.y. (<17 ka) Comments: Recurrence interval estimated by Dolan and others (2000 #5964) based on 2–3 rupture events in past 16–17 k.y. and at least 6 rupture events in past 50 k.y.
Slip-rate category	Between 1.0 and 5.0 mm/yr Comments: Dolan and others (1995 #5965) assign 1.0–1.5 mm/yr; 0.5–0.6 mm/yr for the dip-slip component. Clark and others (1984 #2876) estimated 0.27–0.39 mm/yr for the Potrero Canyon fault based on vertical separation only; Petersen and Wesnousky (1994 #5962) report 3–5 mm/yr late-Pleistocene/Holocene slip rate from unpublished work by Molnar (1991, report to Southern California Earthquake Center) but the estimates by Molnar are poorly constrained. Slip rate assigned to the fault by Petersen and others (1996 #4860) for probabilistic seismic hazard assessment for the State of California was 1.0 mm/yr (with minimum and maximum assigned slip rates of 0.5 mm/yr and 1.5 mm/yr, respectively assuming 1:1/H:V and that Potrero Canyon fault carries half of slip.
Date and Compiler(s)	2000 Jerome A. Treiman, California Geological Survey William A. Bryant, California Geological Survey
References	#5953 Barbat, W.F., 1958, The Los Angeles Basin area, California, in Weeks, L.G., ed., Habitat of Oil: American Association of Petroleum Geologists, p. 62-77. #2876 Clark, M.M., Harms, K.H., Lienkaemper, J.J., Harwood, D.S., Lajoie, K.R., Matti, J.C., Perkins, J.A., Rymer, M.J., Sarna-Wojcicki, A.M., Sharp, R.V., Sims, J.D., Tinsley, J.C., III, and Ziony, J.I., 1984, Preliminary slip rate table and map of late Quaternary faults of California: U.S. Geological Survey Open-File Report 84-106, 12 p., 5 plates, scale 1:1,000,000. #5963 Dolan, J.F., and Pratt, T.L., 1997, High-resolution seismic reflection profiling of the Santa Monica fault zone, west Los Angeles, California: Geophysical Research Letters, v. 24, no. 16, p. 2051-2054. #5917 Dolan, J.F., and Sieh, K., 1992, Tectonic geomorphology of the northern Los Angeles basin—Seismic hazards and kinematics of young fault movement, in Ehlig, P.L., and Steiner, E.A., eds., Engineering geology field trips, Orange County, Santa Monica Mountains, Malibu: Association of Engineering Geologists, Southern California Section, 35th Annual Meeting, Long Beach, California, October 2-9, 1992, p. B20-B26. #5964 Dolan, J.F., Sieh, K., and Rockwell, T.K., 2000, Late Quaternary activity and seismic potential of the Santa Monica fault system, Los Angeles, California: Geological Society of America Bulletin, v. 112, p. 1559-1581. #5965 Dolan, J.F., Sieh, K., Rockwell, T.K., Yeats, R.S., Shaw, J., Suppe, J., Huftile, G.J., and Gath, E.M., 1995, Prospects for larger or more frequent earthquakes in the Los Angeles metropolitan region: Science, v. 267, p. 199-205. #5973 Hill, R.L., 1979, Potrero Canyon fault and University High School escarpment, in Keaton, J.R., ed., Field guide to selected engineering geologic features, Santa Monica Mountains: Association of Engineering Geologists, Southern California Section, Annual Field Trip, May 19, 1979, p. 83-103. #4959 Hill, R.T., 1928, Southern California geology and Los Angeles earthquakes: Los Angeles, Southern California Academy of Sciences, 232 p. #5921 Hoots, H.W., 1931, Geology of the eastern part of the Santa Monica Mountains, Los Angeles County, California: U.S. Geological Survey Professional Paper 165-C, p. 83-134, scale 1:24,000. #5922 Hornafius, J.S., Luyendyk, B.P., Terres, R.R., and Kamerling, M.J., 1986, Timing and extent of Neogene tectonic rotation in the western Transverse Ranges, California: Geological Society of America Bulletin, v. 97, p. 1476-1487. #2878 Jennings, C.W., 1994, Fault activity map of California and adjacent areas, with locations of recent volcanic eruptions: California Division of Mines and Geology Geologic Data Map 6, 92 p., 2 pls., scale 1:750,000. #5945 Junger, A., and Wagner, H.C., 1977, Geology of the Santa Monica and San Pedro basins, California Continental Borderland: U.S. Geological Survey Map MF-820, scale 1:250,000. #5924 Lamar, D.L., 1961, Structural evolution of the northern margin of the Los Angeles Basin: Los Angeles, University of California, unpublished Ph.D. dissertation, 142 p. #5967 Lang, H.R., and Dreessen, R.S., 1975, Subsurface structure of the northwestern Los Angeles Basin: California Division of Oil and Gas, Technical Papers TP01, p. 15-21. #5925 Lawson, A.C., Gilbert, G.K., Reid, H.F., Branner, J.C., Leuschner, A.O., Davidson, G., Burckhalter, C., and Campbell, W.W., 1908, Atlas of maps and seismograms accompanying the report of the State Earthquake Investigation Commission upon the California earthquake of April 18, 1906: Carnegie Institution of Washington Publication 87. #5968 McGill, J.T., 1989, Geologic maps of the Pacific Palisades area, Los Angeles, California: U.S. Geological Survey, Miscellaneous Investigations Map I-1828, scale 1:4,800. #5962 Petersen, M.D., and Wesnousky, S.G., 1994, Review, fault slip rates and earthquake histories for active faults in southern California: Bulletin of the Seismological Society of America, v. 84, no. 5, p. 1608-1649. #4860 Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Lienkaemper, J.J., McCrory, P.A., and Schwartz, D.P., 1996, Probabilistic seismic hazard assessment for the State of California: California Department of Conservation, Division of Mines and Geology Open-File Report 96-08 (also U.S. Geological Open-File Report 96-706), 33 p. #5969 Pratt, T.L., Dolan, J.F., Odum, J.K., Stephenson, W.J., Williams, R.A., and Templeton, M.E., 1998, Multiscale seismic imaging of active fault zones for hazard assessment—A case study of the Santa Monica fault zone, Los Angeles, California: Geophysics, v. 63, p. 479-489. #7949 Sorlien, C.C., Kamerling, M.J., Seeber, L., and Broderick, K.G., 2006, Restraining segments and reactivation of the Santa Monica-Dume-Malibu Coast fault system, offshore Los Angeles, California: Journal of Geophysical Research, v. 111, B11402, 22 p., map scale 1:500,000, doi:70.1029/2005JB003632. #5970 Tsutsumi, H., Yeats, R.S., Hummon, C., Schneider, C.L., and Huftile, G.J., 1994, Subsurface analysis of the active trace of the Santa Monica fault and the northern extension of the Newport-Inglewood fault zone, Los Angeles Basin, California: Eos, Transactions of the American Geophysical Union, v. 75, no. 44, supplement, p. 622. #8344 Vedder, J.G., Greene, H.G., Clarke, S.H., and Kennedy, M.P., 1986, Geologic map of the mid‑southern California continental margin, Map No. 2A (Geology), in Greene, H.G., and Kennedy, M.P., eds., Geology of the mid-southern California continental margin: California Division of Mines and Geology California Continental Margin Geologic Map Series, Area 2 of 7, scale 1:250,000. #5950 Wright, T.L., 1991, Structural geology and tectonic evolution of the Los Angeles Basin, California, in Biddle, K.T., ed., Active margin basin: American Association of Petroleum Geologists Memoir 52, p. 35–134. #5930 Yerkes, R.F., McCulloh, T.H., Schoellhamer, J.E., and Vedder, J.G., 1965, Geology of the Los Angeles Basin, California—An introduction: U.S. Geological Survey Professional Paper 420-A, 57 p.