Faults--Offshore of Fort Ross Map Area, California

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: S.Y. Johnson

Originator: S.R. Hartwell

Originator: M.W. Manson

Publication_Date: 2014

Title: Faults--Offshore of Fort Ross Map Area, California

Geospatial_Data_Presentation_Form: vector digital data

Larger_Work_Citation:

Citation_Information:

Originator: Samuel Y. Johnson

Originator: Peter Dartnell

Originator: Nadine E. Golden

Originator: Stephan R. Hartwell

Originator: H. Gary Greene

Originator: Mercedes D. Erdey

Originator: Guy R. Cochrane

Originator: Janet L. Watt

Originator: Rikk G. Kvitek

Originator: Michael W. Manson

Originator: Charles A. Endris

Originator: Bryan E. Dieter

Originator: Lisa M. Krigsman

Originator: Ray W. Sliter

Originator: Erik N. Lowe

Originator: John L. Chin

Publication_Date: 2015

Title:

California State Waters Map Series—Offshore of Fort Ross, California

Geospatial_Data_Presentation_Form: map

Series_Information:

Series_Name: Open-File Report

Issue_Identification: OFR 2015–1211

Publication_Information:

Publication_Place: Reston, VA

Publisher: U.S. Geological Survey

Online_Linkage: https://dx.doi.org/10.3133/ofr20151211

Larger_Work_Citation:

Citation_Information:

Originator: Nadine E. Golden

Publication_Date: 2014

Title: California State Waters Map Series Data Catalog

Geospatial_Data_Presentation_Form: database

Series_Information:

Series_Name: Data Series

Issue_Identification: DS 781

Publication_Information:

Publication_Place: Reston, VA

Publisher: U.S. Geological Survey

Online_Linkage: https://pubs.usgs.gov/ds/781/

Online_Linkage:

https://www.sciencebase.gov/arcgis/rest/services/Catalog/555cdb07e4b0a92fa7eb81c5/MapServer

Online_Linkage:

https://www.sciencebase.gov/arcgis/services/Catalog/555cdb07e4b0a92fa7eb81c5/MapServer/WMSServer?request=GetCapabilities&service=WMS

Description:

Abstract:

This part of DS 781 presents data for faults for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included in "Faults_OffshoreFortRoss.zip," which is accessible from https://pubs.usgs.gov/ds/781/OffshoreFortRoss/data_catalog_OffshoreFortRoss.html.

The Offshore of Fort Ross map area is cut by the northwest-trending San Andreas Fault, the right-lateral transform boundary between the North American and Pacific tectonic plates. The San Andreas extends across the inner shelf in the southern part of the map, then crosses the shoreline at Fort Ross and continues onland for about 75 km to the east flank of Point Arena (fig. 8-1). Seismic-reflection data are used to map the offshore fault trace, and reveal a relatively simple, 200- to 500-m wide zone typically characterized by one or two primary strands. About 1500 m west of the San Andreas Fault, the mid shelf (between water depths of 40 m and 70 m) in the southernmost part of the map area includes an about 5-km-wide field of elongate, shore-normal sediment lobes (unit Qmsl). Individual lobes within the field are as much as 650-m long and 200-m wide, have as much as 1.5 m (check with Steve) of relief above the surrounding smooth seafloor, and are commonly connected with upslope chutes. Given their morphology and proxmity to the San Andreas fault, we infer that these lobes result from slope failures associated with strong ground motions triggered by large San Andreas earthquakes.

Movement on the San Andreas has juxtaposed different coastal bedrock blocks (Blake and others, 2002). Rocks east of the fault that occur along the coast and in the nearshore belong to the late Tertiary, Cretaceous, and Jurassic Franciscan Complex, either sandstone of the Coastal Belt or Central Belt (unit TKfs) or melange of the central terrane (unit fsr). Bedrock west of the fault are considered part of the Gualala Block (Elder, 1998) and include the Eocene and Paleocene German Rancho Formation (unit Tgr) and the Miocene sandstone and mudstone of the Fort Ross area (unit Tsm).

This section of the San Andreas Fault onland has an estimated slip rate of about 17 to 25 mm/yr (Bryant and Lundberg, 2002). The devastating Great 1906 California earthquake (M 7.8) is thought to have nucleated on the San Andreas Fault about 100 kilometers south of this map area offshore of San Francisco (e.g., Bolt, 1968; Lomax, 2005), with the rupture extending northward through the Offshore of Fort Ross map area to the south flank of Cape Mendocino. Emergent marine terraces along the coast in the Offshore of Fort Ross map area record recent contractional deformation associated with the San Andreas Fault system. Prentice and Kelson (2006) report uplift rates of 0.3 to 0.6 mm/yr for a late Pleistocene terrace exposed at Fort Ross, and this recent uplift must also have affect the nearshore and inner shelf.

Previously, McCulloch (1987) mapped a nearshore (within 3 to 5 km of the coast) fault zone from Point Arena to Fort Ross (Fig. 8-1) using primarily deeper industry seismic-reflection data. Subsequently, Dickinson and others (2005) named this structure the "Gualala Fault." Our mapping, also based on seismic-reflection data, reveals this structure as a steep, northeast trending fault and similarly shows the fault ending to the south in the northern part of the Offshore of Fort Ross map area. We have designated the zone of faulting and folding above this structure the "Gualala Fault deformation zone."

Faults were primarily mapped by interpretation of seismic reflection profile data (see field activity S-8-09-NC). The seismic reflection profiles were collected between 2007 and 2010.

References Cited

Blake, M.C., Jr., Graymer, R.W., and Stamski, R.E., 2002, Geologic map and map database of western Sonoma, northernmost Marin, and southernmost Mendocino counties, California: U.S. Geological Survey Miscellaneous Field Studies Map 2402, scale 1:100,000.

Bolt, B.A., 1968, The focus of the 1906 California earthquake: Bulletin of the Seismological Society of America, v. 58, p. 457-471.

Bryant, W.A., and Lundberg, M.M., compilers, 2002, Fault number 1b, San Andreas fault zone, North Coast section, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, accessed April 4, 2013, at http://earthquakes.usgs.gov/hazards/qfaults.

Dickinson, W.R., Ducea, M., Rosenberg, L.I., Greene, H.G., Graham, S.A., Clark, J.C., Weber, G.E., Kidder, S., Ernst, W.G., and Brabb, E.E., 2005, Net dextral slip, Neogene San Gregorio-Hosgri Fault Zone, coastal California: Geologic evidence and tectonic implications: Geological Society of America Special Paper 391, 43 p.

Elder, W.P., ed., 1998, Geology and tectonics of the Gualala Block, northern California: Pacific Section, Society of Economic Paleontologists and Mineralogists, Book 84, 222 p.

Lomax, A., 2005, A reanalysis of the hypocentral location and related observations for the Great 1906 California earthquake: Bulletin of the Seismological Society of America, v. 95, p. 861-877.

McCulloch, D.S., 1987, Regional geology and hydrocarbon potential of offshore central California, in Scholl, D.W., Grantz, A., and Vedder, J.G., eds., Geology and Resource Potential of the Continental Margin of Western North America and Adjacent Oceans -- Beaufort Sea to Baja California: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources, Earth Science Series, v. 6., p. 353-401.

Prentice, C.S., and Kelson, K.I., 2006, The San Andreas fault in Sonoma and Mendocino counties, in Prentice, C.S., Scotchmoor, J.G., Moores, E.M., and Kiland, J.P., eds., 1906 San Francisco Earthquake Centennial Field Guides: Field trips associated with the 100th Anniversary Conference, 18-23 April 2006, San Francisco, California: Geological Society of America Field Guide 7, p. 127-156.

Purpose:

To expand geologic mapping to the seafloor within the California's State Waters, to update coastal geologic mapping, and to contribute to a uniform regional geologic database, which can be used in geographic information systems. Additionally, to provide a geologic map for the public and geoscience community to aid in assessments and mitigation of geologic hazards in the Fort Ross coastal region and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore. This information is not intended for navigational purposes.

Supplemental_Information:

Map political location: San Mateo County, California Compilation scale: 1:24,000 Base maps used are hillshades generated from IfSAR, LiDAR, and multibeam mapping both onshore and offshore (see Bathymetry--Offshore of Fort Ross Map Area, California).

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 2009

Ending_Date: 2009

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: none planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -123.31

East_Bounding_Coordinate: -123.11

North_Bounding_Coordinate: 38.53

South_Bounding_Coordinate: 38.40

Keywords:

Theme:

Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD)

Theme_Keyword: Oceans > Bathymetry/SeafloorTopography > Bathymetry

Theme_Keyword: Oceans > Bathymetry/SeafloorTopography > Seafloor Topography

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category

Theme_Keyword: geoscientificInformation

Theme_Keyword: environment

Theme_Keyword: oceans

Theme_Keyword: imageryBaseMapsEarthCover

Place:

Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)

Place_Keyword: Pacific Ocean

Place_Keyword: State of California

Place_Keyword: Fort Ross

Place_Keyword: Jenner

Place_Keyword: Russian River

Access_Constraints:

If physical samples or materials are available, constraints on their on-site access are described in "WR CMG Sample Distribution Policy" at URL: http://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.html

Use_Constraints:

This information is not intended for navigational purposes.
Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.
Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.
This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: USGS Pacific Coastal and Marine Science Center

Contact_Person: Stephen Hartwell

Contact_Position: Geologist

Contact_Address:

Address_Type: physical address

Address: 400 Natural Bridges Drive

City: Santa Cruz

State_or_Province: CA

Postal_Code: 95060

Country: USA

Contact_Voice_Telephone: (831) 460-7814

Contact_Facsimile_Telephone: (831) 427-4748

Contact_Electronic_Mail_Address: shartwell@usgs.gov

Native_Data_Set_Environment:

Microsoft Windows Server 2008 R2 Version 6.1 (Build 7601) Service Pack 1; ESRI ArcGIS 10.0.0.2414

Browse_Graphic:

Browse_Graphic_File_Name:

<https://pubs.usgs.gov/ds/781/OffshoreFortRoss/images/Faults_OffshoreFortRoss.jpg>

Browse_Graphic_File_Description: Faults offshore Fort Ross.

Browse_Graphic_File_Type: JPEG

Data_Quality_Information:

Logical_Consistency_Report:

Map elements were visually checked for overshoots, undershoots, duplicate features, and other errors by the lead authors and by the GIS technician(s) who created the digital database. Review drafts of the map were reviewed internally by at least two other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards.

Completeness_Report:

Data are complete: no offshore features that could be accurately identified and represented at the compilation scale of 1:24,000 were eliminated or generalized. The smallest area represented is approximately 100 square meters. All geospatial database elements are attributed.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Faults were primarily mapped by interpretation of seismic reflection profile data (see field activity S-8-09-NC). Faults lines were digitized by heads-up screen digitization on to shot-point picks from seismic- line navigation data - each shot point has an associated lat/long in the survey data. Error is introduced from layback, as well as from interpretation of oblique features, so horizontal accuracy of fault and fold location is estimated to be on the order of 10 to 20 meters.

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator:

U.S. Geological Survey (USGS) , Coastal and Marine Geology Program (CMGP)

Publication_Date: 2013

Title:

Subbottom survey data of field activity S-8-09-NC in Stinson Beach to Point Arena (CA) from 09/08/2009 to 09/30/2009

Publication_Information:

Publication_Place: Menlo Park, CA

Publisher:

U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)

Online_Linkage: http://walrus.wr.usgs.gov/infobank/gos/s-8-09-nc.fmeta.xml

Online_Linkage:

http://walrus.wr.usgs.gov/infobank/s/s809nc/html/s-8-09-nc.meta.html

Type_of_Source_Media: ASCII lat/long shot point files

Source_Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20090908

Ending_Date: 20090930

Source_Currentness_Reference: ground condition

Source_Citation_Abbreviation: S-8-09-NC

Source_Contribution:

Digital seismic data used to interpret subsurface geologic structure

Process_Step:

Process_Description:

Faults were mapped onto shot lines based on the latitude and longitude of seismic picks from field activity S-8-09-NC.

Process_Date: 2013

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: String

Point_and_Vector_Object_Count: 34

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Map_Projection:

Map_Projection_Name: WGS 1984 UTM Zone 10N

Transverse_Mercator:

Scale_Factor_at_Central_Meridian: 0.9996

Longitude_of_Central_Meridian: -123.0

Latitude_of_Projection_Origin: 0.0

False_Easting: 500000.0

False_Northing: 0.0

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 0.0001

Ordinate_Resolution: 0.0001

Planar_Distance_Units: Meter

Geodetic_Model:

Horizontal_Datum_Name: D WGS 1984

Ellipsoid_Name: WGS 1984

Semi-major_Axis: 6378137.0

Denominator_of_Flattening_Ratio: 298.257223563

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: Faults

Entity_Type_Definition: lines representing mapped faults

Entity_Type_Definition_Source: This report

Attribute:

Attribute_Label: FID

Attribute_Definition: Internal feature number.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: Shape

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: FGDCRefNo

Attribute_Definition:

FGDC Digital Cartographic Standard for geologic map symbolization

Attribute_Definition_Source: This report

Attribute_Domain_Values:

Unrepresentable_Domain:

text field containing the reference number for the FGDC Digital Cartographic Standard for geologic map symbolization

Attribute:

Attribute_Label: Shape_Leng

Attribute_Definition: Length of feature in internal units.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Positive real numbers that are automatically generated.

Metadata_Reference_Information:

Metadata_Date: 2013

Metadata_Review_Date: 20140922

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: U.S. Geological Survey, Coastal and Marine Geology Program

Contact_Person: Stephen R. Hartwell

Contact_Address:

Address_Type: mailing and physical address

Address: 400 Natural Bridges Drive

City: Santa Cruz

State_or_Province: CA

Postal_Code: 95060-5792

Country: US

Contact_Voice_Telephone: 831-460-7814

Contact_Facsimile_Telephone: 831-427-4748

Contact_Electronic_Mail_Address: shartwell@usgs.gov

Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998