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/3225/

Suggested Citation: Johnson, S.Y., Phillips, E.L., Ritchie, A.C., Wong, F.L., and Sliter, R.W., 2012, Local (Hueneme Canyon and vicinity) 

and regional (offshore 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., Greene, H.G., 

Krigsman, L.M., Endris, C.A., Clahan, K.B., Sliter, R.W., Wong, F.L., Yoklavich, M.M., and Normark, W.R. (S.Y. Johnson, ed.), California 

State Waters Map Series—Hueneme Canyon and vicinity: U.S. Geological Survey Scientific Investigations Map 3225, pamphlet 41 p., 

12 sheets, available at http://pubs.usgs.gov/sim/3225/.

Local (Hueneme Canyon and Vicinity) and Regional (Offshore Refugio Beach to Hueneme Canyon)

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

By

Samuel Y. Johnson, Eleyne L. Phillips, Andrew C. Ritchie, Florence L. Wong, and Ray W. Sliter

2012

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 Hueneme Canyon and vicinity 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 data set was set aside in 

favor of a surface determined by subtracting the modified thickness data from multibeam bathymetry collected separately (see sheet 1; see also, Wong and others, 2012). 

The depth of this surface in the Hueneme Canyon and vicinity map area ranges from 

12 to 190 m (Map D).

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 northern strand of the Red Mountain Fault Zone (RMFZ); (2) 

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

(PPF); (3) between the Pitas Point Fault and 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 3.6 

m); (2) a transitional zone (domain 2; mean sediment thickness of 17.6 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, 38.7, 

and 28.3 m, respectively).

In the Hueneme Canyon and vicinity map area (Maps A, B), mean sediment 

thickness northwest and southeast of Hueneme Canyon is 38.1 and 31.9 m, respectively. The variability reflects the influence of channel cut and fill associated with the 

heads of the smaller, unnamed submarine canyons east of Hueneme Canyon, as well as 

perhaps the lower sediment supply owing to their location on the downdrift flank of 

Hueneme Canyon.

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 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, 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/.

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

8000 6000 4000 2000 0 8000 FEET

2 1 0 2 KILOMETERS

SCALE 1:50 000

2 1 0 2 MILES

80 000 60 000 40 000 20 000 0 80 000 FEET

20 10 0 20 KILOMETERS

SCALE 1:300 000

20 10 0 20 MILES

40 000 30 000 20 000 10 000 0 40 000 FEET

10 5 0 10 KILOMETERS

SCALE 1:200 000

10 5 0 10 MILES

APPROXIMATE MEAN

DECLINATION, 2012

13°

MAGNETIC NORTH

TRUE NORTH

MAGNETIC NORTH

TRUE NORTH

APPROXIMATE MEAN

DECLINATION, 2012

13°

APPROXIMATE MEAN

DECLINATION, 2012

13°

MAGNETIC NORTH

TRUE NORTH

Onshore elevation data from NOAA Coastal Services 

Center (data collected by EarthData International in 

2002-2003) and from U.S. Army Corps of Engineers (data 

collected by Fugro Pelagos in 2009). 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

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

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 July 25, 2012

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

Mugu

Canyon

Area of Hueneme Canyon 

and vicinity map

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 to 

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

RMFZ

PPF

ORF

34°30'

34°15'

34°

119°

119°45'

119°30'

119°15'

120°

120°15'

34°30'N

120°15'

120°

119°45'

119°30'

119°15'

119°

34°15'

34°

Santa Barbara

Ventura

Goleta

Oxnard

Hueneme

Canyon

 Refugio

 Beach

Area of Hueneme Canyon 

and vicinity map

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 

to Holocene sediment, in meters

Depth-to-base 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

120°30' 120° 119°30' 119°

120°30' 120° 119°30'

34°30'

34°

34°30'

34°

Area of Hueneme 

Canyon and vicinity map

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

MA

Ventura

Refugio

 Beach

Goleta Santa

Barbara

Area of Maps D, E

34°10'

34°5'

34°10'

34°5'

119°20' 119°15' 119°10'

119°20' 119°15' 119°10'

Oxnard

Port of Hueneme

Channel

Islands 

Harbor

Map B

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 to 

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

ONE MILE = 0.869 NAUTICAL MILES

ONE MILE = 0.869 NAUTICAL MILES

ONE MILE = 0.869 NAUTICAL MILES

119°20' 119°15' 119°10'

119°20' 119°15' 119°10'

34°10'

34°5'

34°10'

34°5'

Oxnard

Port of Hueneme

Channel 

Islands 

Harbor

Map A

-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 to 

Holocene sediment, in meters

Depth-to-base 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

Montalvo Anticline

Montalvo Fault

Montalvo Anticline

Montalvo Fault

Scientific Investigations Map 3225

Sheet 9 of 12

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey