Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the 

U.S. Government

This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary between electronic plotters 

and between X and Y directions on the same plotter, and paper may change size due to atmospheric conditions; therefore, scale and 

proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3302/

Suggested Citation: Johnson, S.Y., Conrad, J.E., Phillips, E.L., Ritchie, A.C., Wong, F.L., Sliter, R.W., Draut, A.E., and Hart, P.E., 2014, 

Local (Offshore of Coal Oil Point map area) and regional (offshore from Refugio Beach to Hueneme Canyon) shallow-subsurface 

geology and structure, Santa Barbara Channel, California, sheet 9 in Johnson, S.Y., Dartnell, P., Cochrane, G.R., Golden, N.E., Phillips, 

E.L., Ritchie, A.C., Kvitek, R.G., Dieter, B.E., Conrad, J.E., Lorenson, T.D., Krigsman, L.M., Greene, H.G., Endris, C.A., Seitz, G.G., 

Finlayson, D.P., Sliter, R.W., Wong, F.L., Erdey, M.D., Gutierrez, C.I., Leifer, I., Yoklavich, M.M., Draut, A.E., Hart, P.E., Hostettler, F.D., 

Peters, K.E., Kvenvolden, K.A., Rosenbauer, R.J., and Fong, G. (S.Y. Johnson and S.A. Cochran, eds.), California State Waters Map 

Series—Offshore of Coal Oil Point, California: U.S. Geological Survey Scientific Investigations Map 3302, pamphlet 57 p., 12 sheets, 

scale 1:24,000, http://dx.doi.org/10.3133/sim3302.

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3302

The regional pattern of faults and of earthquakes occurring between 1932 and 

2010 that have inferred or measured magnitudes greater than 2.0 is shown on Map C. 

Fault locations are based on our mapping within California’s State Waters and on a 

generalized compilation of mapping from Heck (1998), Minor and others (2009), and 

Jennings and Bryant (2010). Earthquake data are from the Southern California 

Earthquake Catalog (Southern California Earthquake Data Center, 2010). Although 

earthquake locations have been determined by the CalTech network since 1932, 

significantly greater precision began in 1969 with installation of a U.S. Geological 

Survey (USGS) seismographic network (Lee and Vedder, 1973; Southern California 

Earthquake Data Center, 2010). Epicentral data indicate that recent seismicity in the 

eastern and central Santa Barbara Channel is characterized by earthquake swarms, 

relatively frequent minor earthquakes, and infrequent major earthquakes.

REFERENCES CITED

Caldwell, R.J., Taylor, L.A., Eakins, B.W., Carignan, K.S., Grothe, P.R., Lim, E., and 

Friday, D.Z., 2010, Digital elevation models of Santa Monica, California—

Procedures, data sources and analysis: NOAA Technical Memorandum NESDIS 

NGDC-46, NOAA National Geophysical Data Center, available at 

http://www.ngdc.noaa.gov/dem/squareCellGrid/download/663.

Carignan, K.S., Taylor, L.A., Eakins, B.W., Warnken, R.R., Lim, E., and Medley, P.R., 

2009, Digital elevation model of Santa Barbara, California—Procedures, data 

sources, and analysis: NOAA Technical Memorandum NESDIS NGDC-29, 

NOAA National Geophysical Data Center, available at http://www.ngdc.noaa.gov/

dem/squareCellGrid/download/603.

Heck, R.G., 1998, Santa Barbara Channel regional formline map, top Monterey 

Formation, in Kunitomi, D.S., Hopps, T.E., and Galloway, J.M., eds., Structure 

and petroleum geology, Santa Barbara Channel, California: American Association 

of Petroleum Geologists, Pacific Section, and Coast Geological Society, 

Miscellaneous Publication 46, 1 plate.

Jennings, C.W., and Bryant, W.A., 2010, Fault activity map of California: California 

Geological Survey Geologic Data Map no. 6, scale 1:750,000.

Lee, W.H.K., and Vedder, J.G., 1973, Recent earthquake activity in the Santa Barbara 

Channel region: Bulletin of the Seismological Society of America, v. 63, p. 

1,757–1,773.

Minor, S.A., Kellogg, K.S., Stanley, R.G., Gurrola, L.D., Keller, E.A., and Brandt, 

T.R., 2009, Geologic map of the Santa Barbara coastal plain area, Santa Barbara 

County, California: U.S. Geological Survey Scientific Investigations Map 3001, 

scale 1:25,000, 1 sheet, pamphlet 38 p., available at http://pubs.usgs.gov/sim/

3001/.

Southern California Earthquake Data Center, 2010, Southern California Earthquake 

Catalog: Southern California Earthquake Data Center database, accessed April 5, 

2011, at http://www.data.scec.org/eq-catalogs/index.html. 

Wong, F.L., Phillips, E.L., Johnson, S.Y., and Sliter, R.W., 2012, Modeling of depth to 

base of Last Glacial Maximum and seafloor sediment thickness for the California 

State Waters Map Series, eastern Santa Barbara Channel, California: U.S. 

Geological Survey Open-File Report 2012–1161, 16 p., available at 

http://pubs.usgs.gov/of/2012/1161/. 

DISCUSSION

This sheet includes maps that show the thickness and the depth to base of 

uppermost Pleistocene and Holocene (in other words, post–Last Glacial Maximum) 

deposits for the Offshore of Coal Oil Point map area (Maps A, B), as well as for a 

larger area that extends about 115 km along the coast from Hueneme Canyon to 

Refugio Beach (Maps D, E) to establish a regional context. To make these maps, water 

bottom and depth to base of the post–Last Glacial Maximum horizons were mapped 

from seismic-reflection profiles. The difference in the two horizons was exported for 

every shot point as XY coordinates (UTM zone 11) and two-way travel time (TWT). 

The thickness of the post–Last Glacial Maximum unit (Maps B, E) was determined by 

applying a sound velocity of 1,600 m/sec to the TWT. The thickness points were 

interpolated to a preliminary continuous surface, overlaid with zero-thickness bedrock 

outcrops (sheet 10 of this report), and contoured (Wong and others, 2012). Data within 

Hueneme Canyon were excluded from the contouring because the seismic-reflection 

data are too sparse to adequately image the highly variable changes in sediment 

thickness that characterize the canyon (Maps A, B, D, E).

Several factors required manual editing of the preliminary thickness maps to 

make the final products. The Red Mountain Fault Zone (RMFZ), Pitas Point Fault 

(PPF), and Oak Ridge Fault (ORF) disrupt the sediment sequence in the region (Maps 

D, E). The data points also are dense along tracklines (about 1 m apart) and sparse 

between tracklines (1–2 km apart), resulting in contouring artifacts. To incorporate the 

effect of the faults, to remove irregularities from interpolation, and to reflect other 

geologic information and complexity, the resulting interpolated contours were 

modified. Contour modifications and regridding were repeated several times to 

produce the final regional sediment-thickness map (Wong and others, 2012). 

 Data to determine the depth to base of the post–Last Glacial Maximum unit was 

similarly processed and contoured. However, this preliminary dataset was set aside in 

favor of a surface determined by subtracting the modified thickness data from 

multibeam bathymetry collected separately (see sheet 1). The depth of this surface in 

the Hueneme Canyon to Refugio Beach area ranges from 12 to 190 m (Map D; see 

also, Wong and others, 2012).

 Five different “domains” of sediment thickness, which are bounded either by 

faults or by Hueneme Canyon, are recognized on the regional maps (Maps D, E): (1) 

Refugio Beach to the south strand of the Red Mountain Fault Zone (RMFZ); (2) 

between the south strand of the Red Mountain Fault Zone and the Pitas Point Fault 

(PPF); (3) between the Pitas Point Fault and the Oak Ridge Fault (ORF); (4) between 

the Oak Ridge Fault and Hueneme Canyon; and (5) south of Hueneme Canyon. These 

data highlight the contrast among three general zones of sediment thickness: (1) the 

uplifted, sediment-poor Santa Barbara shelf (domain 1; mean sediment thickness of 3.5 

m); (2) a transitional zone (domain 2; mean sediment thickness of 18.0 m); and (3) the 

subsiding, sediment-rich delta and shelf offshore of the Ventura and Santa Clara Rivers 

and Calleguas Creek (domains 3, 4, and 5; mean sediment thicknesses of 39.3, 38.9, 

and 28.3 m, respectively).

In the Offshore of Coal Oil Point map area, sediment thickness ranges from 0 to 

about 17 m, with a mean thickness of 4.0 m. The thickest sediment accumulations are 

in three nearshore to inner shelf depocenters, which have delta-mouth-bar morphology, 

sourced by local, steep watersheds to the north in the Santa Ynez Mountains. Locally 

thicker sediment (as much as 15 m) also is present on the upper slope (below the shelf 

break), with the thickest accumulations (about 15 m) representing midslope landslide 

debris. Sediment is notably thin or absent in much of the midshelf to outer shelf area.

120° 119°40' 119°20' 119°

34°

34°20'

Kilometers 0 5 10

0 4 8 Nautical Miles

Santa Barbara Channel

 Santa 

Barbara

Ventura

CALIF.

MAP LOCATION

Limit of California’s

 State Waters

Santa Cruz Island Santa Rosa Island

Area of

 Map

Anacapa

 Island

Local (Offshore of Coal Oil Point Map Area) and Regional (Offshore from Refugio Beach to Hueneme Canyon)

Shallow-Subsurface Geology and Structure, Santa Barbara Channel, California

By

Samuel Y. Johnson, James E. Conrad, Eleyne L. Phillips, Andrew C. Ritchie, Florence L. Wong, Ray W. Sliter, Amy E. Draut, and Patrick E. Hart

2014

ONE MILE = 0.869 NAUTICAL MILES

1 0.5 0 1 KILOMETER

7000 3500 0 7000 FEET

2 1 0 2 MILES

SCALE 1:50 000

ONE MILE = 0.869 NAUTICAL MILES

20 10 0 20 KILOMETERS

80000 60000 40000 20000 0 80000 FEET

20 10 0 20 MILES

SCALE 1:300 000

ONE MILE = 0.869 NAUTICAL MILES

10 5 0 10 KILOMETERS

40000 30000 20000 10000 0 40000 FEET

10 5 0 10 MILES

SCALE 1:200 000

APPROXIMATE MEAN

DECLINATION, 2014

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

APPROXIMATE MEAN

DECLINATION, 2014

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

APPROXIMATE MEAN

DECLINATION, 2014

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

Onshore elevation data from NOAA Coastal Services Center (data collected by EarthData International in 

2002-2003). Shaded-relief bathymetry from data collected by Monterey Bay Aquarium Research Institute in 1998, by 

U.S. Geological Survey in 2006, by California State University, Monterey Bay, Seafloor Mapping Lab in 2006-2007, 

and by Fugro Pelagos for U.S. Army Corps of Engineers in 2009; data compiled in NOAA Tsunami Inundation Project 

1/3 arc-second DEMs for Santa Barbara, CA (Carignan and others, 2009), and Santa Monica, CA (Caldwell and 

others, 2010). California's State Waters limit from NOAA Office of Coast Survey

Universal Transverse Mercator projection, Zone 11N

NOT INTENDED FOR NAVIGATIONAL USE

Onshore elevation data from NOAA Coastal Services 

Center (data collected by EarthData International in 

2002-2003). California's State Waters limit from NOAA 

Office of Coast Survey 

Universal Transverse Mercator projection, Zone 11N

Depth and thickness mapped by Samuel Y. 

Johnson and Eleyne L. Phillips, 2010-2011

GIS database and digital cartography by Eleyne L. 

Phillips, Andrew C. Ritchie, and Florence L. Wong

Onshore elevation data from NOAA Coastal Services 

Center (data collected by EarthData International in 

2002-2003) and from National Elevation Dataset, 2011. 

California's State Waters limit from NOAA Office of Coast 

Survey

Universal Transverse Mercator projection, Zone 11N

Compiled by Andrew C. Ritchie and Samuel Y. 

Johnson, 2011

Depth and thickness mapped by Samuel Y. Johnson and Eleyne L. Phillips, 2010-2011

GIS database and digital cartography by Andrew C. Ritchie, Eleyne L. Phillips, and 

Florence L. Wong

Edited by Taryn A. Lindquist

Manuscript approved for publication June 2, 2014

RMFZ

PPF

ORF

34°30'

34°15'

34°

119°

119°45'

119°30'

119°15'

120°

120°15'

34°30'

34°15'

34°

119°

119°45'

119°30'

119°15'

120°

120°15'

Santa Barbara

Ventura

Goleta

Hueneme

 Canyon

Oxnard

 Refugio

 Beach

Map E

0 – 0.1

0.1 – 2.5

2.5 – 5

5 – 7.5

7.5 – 10

10 – 12.5

12.5 – 15

15 – 17.5

17.5 – 20

20 – 22.5

22.5 – 25

25 – 27.5

27.5 – 30

30 – 32.5

32.5 – 35

35 – 37.5

37.5 – 40

40 – 42.5

42.5 – 45

45 – 47.5

47.5 – 50

50 – 52.5

52.5 – 55

55 – 57.5

EXPLANATION

Thickness of uppermost Pleistocene

and Holocene sediment, in meters 

Thickness contours

Index (10-m intervals)

Intermediate

Fault—ORF, Oak Ridge Fault; PPF, 

Pitas Point Fault; RMFZ, Red 

Mountain Fault Zone

3-nautical-mile limit of California’s 

State Waters

Offshore of Coal 

Oil Point map area

Mugu

Canyon

RMFZ

PPF

ORF

34°30'

34°15'

34°

119°

119°45'

119°30'

119°15'

120°

120°15'

34°30'

120°15'

120°

119°45'

119°30'

119°15'

119°

34°15'

34°

Santa Barbara

Ventura

Goleta

Oxnard

Hueneme

Canyon

 Refugio

 Beach

Offshore of Coal 

Oil Point map area

Map D

-190 – -185

-185 – -180

-180 – -175

-175 – -170

-170 – -165

-165 – -160

-160 – -155

-155 – -150

-150 – -145

-145 – -140

-140 – -135

-135 – -130

-130 – -125

-125 – -120

-120 – -115

-115 – -110

-110 – -105

-105 – -100

-100 – -95

-95 – -90

-90 – -85

-85 – -80

-80 – -75

-75 – -70

-70 – -65

-65 – -60

-60 – -55

-55 – -50

-50 – -45

-45 – -40

-40 – -35

-35 – -30

-30 – -25

-25 – -20

-20 – -15

-15 – -10

EXPLANATION

Depth to base of uppermost Pleistocene

and Holocene sediment, in meters

Depth-to-base contours

Index (20-m intervals)

Intermediate

Fault—ORF, Oak Ridge Fault; PPF, 

Pitas Point Fault; RMFZ, Red 

Mountain Fault Zone

3-nautical-mile limit of California’s 

State Waters

120°30' 120° 119°30' 119°

120°30' 120° 119°30'

34°30'

34°

34°30'

34°

Offshore of Coal

Oil Point map area

and area of Maps A, B

Map C

2.0 – 2.49

2.5 – 2.99

3.0 – 3.49

 3.5 – 3.99

4.0 – 5.5

3-nautical-mile 

limit of California’s 

State Waters

Fault

EXPLANATION

Regional faults and 

earthquake epicenters, 

1932 – 2010

MAGNITUDE

Ventura

Refugio

 Beach

Goleta Santa

Barbara

Area of Maps D, E

Isla Vista Fault

South Ellwood Anticline

Coal Oil Point Anticline

34°30'

34°25'

34°25'

120° 119°55' 119°50'

120° 119°55' 119°50'

0 – 0.1

0.1 – 2.5

2.5 – 5

5 – 7.5

7.5 – 10

10 – 12.5

12.5 – 15

15 – 17.5

17.5 – 20

20 – 22.5

22.5 – 25

25 – 27.5

EXPLANATION

Thickness of uppermost Pleistocene 

and Holocene sediment, in meters

Thickness contours

Index (10-m intervals)

Intermediate

Fault—Dashed where inferred; dotted 

where concealed

Antiform—Dotted where concealed

Synform—Dotted where concealed

3-nautical-mile limit of California’s 

State Waters

Area of “no data”—Areas where data are 

insufficient for contouring

Coal Oil

 Point

Goleta

Naples

Map B

Isla Vista Fault

South Ellwood Anticline

Coal Oil Point Anticline

120° 119°55' 119°50'

120° 119°55' 119°50'

34°25'

34°30'

34°25'

-190 – -185

-185 – -180

-180 – -175

-175 – -170

-170 – -165

-165 – -160

-160 – -155

-155 – -150

-150 – -145

-145 – -140

-140 – -135

-135 – -130

-130 – -125

-125 – -120

-120 – -115

-115 – -110

-110 – -105

-105 – -100

-100 – -95

-95 – -90

-90 – -85

-85 – -80

-80 – -75

-75 – -70

-70 – -65

-65 – -60

-60 – -55

-55 – -50

-50 – -45

-45 – -40

-40 – -35

-35 – -30

-30 – -25

-25 – -20

-20 – -15

-15 – -10

Depth-to-base contours

Index (20-m intervals)

Intermediate

Fault—Dashed where inferred; 

dotted where concealed

Antiform—Dotted where concealed

Synform—Dotted where concealed

3-nautical-mile limit of California’s 

State Waters

Area of “no data”—Areas where 

data are insufficient for contouring

EXPLANATION

Depth to base of uppermost Pleistocene and 

Holocene sediment, in meters

Coal Oil

 Point

Goleta

Naples

Map A

South Ellwood Syncline

South Ellwood Syncline

Scientific Investigations Map 3302

Sheet 9 of 12

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey