This line shapefile contains fault lines within the offshore area of San Francisco, California. The map area straddles the right-lateral transform boundary between the North American and Pacific plates and is cut by several active faults that cumulatively form a distributed shear zone, including the San Andreas Fault, the eastern strand of the San Gregorio Fault, the Golden Gate Fault, and the Potato Patch Fault (Bruns and others, 2002; Ryan and others, 2008). These faults are covered by Holocene sediments (mostly units Qms, Qmsb, Qmst) with no seafloor expression, and are mapped using seismic-reflection data (see field activities S-15-10-NC and F-2-07-NC). The San Andreas Fault is the primary plate-boundary structure and extends northwest across the map area; it intersects the shoreline 10 km north of the map area at Bolinas Lagoon, and 3 km south of the map area at Mussel Rock. This section of the San Andreas Fault has an estimated slip rate of 17 to 24 mm/yr (U.S. Geological Survey, 2010), and the devastating Great 1906 California earthquake (M 7.8) is thought to have nucleated on the San Andreas a few kilometers offshore of San Francisco within the map area (Bolt, 1968; Lomax, 2005). The San Andreas Fault forms the boundary between two distinct basement terranes, Upper Jurassic to Lower Cretaceous rocks of the Franciscan Complex to the east, and Late Cretaceous granitic and older metamorphic rocks of the Salinian block to the west. Franciscan Complex rocks (unit KJf, undivided) form seafloor outcrops at and north of Point Lobos adjacent to onland exposures. The Franciscan is divided into 13 different units for the onshore portion of this geologic map based on different lithologies and ages, but the unit cannot be similarly divided in the offshore because of a lack of direct observation and (or) sampling. Faults were primarily mapped by interpretation of seismic reflection profile data (see field activities S-15-10-NC and F-2-07-NC). The seismic reflection profiles were collected between 2007 and 2010. A map that shows these data is published in Open-File Report 2015-1068, "California State Waters Map Series--Offshore of San Francisco, California." This layer is part of USGS Data Series 781.

PI: Steven G. Wesnousky, University of Nevada, Reno
The requested survey area consisted of 1-km wide swaths centered along 335 km of fault centerlines. There were a total of 44 fault segments for 12 fault lines, totaling a nominal 335 km² of map area. The faults are spread throughout an area of 15,600 km ² of central western Nevada east of Lake Tahoe. The faults' names and 4 letter identifiers used for the data products are: Antelope Valley (AntV), Benton (Bent), Benton North (BntN), Bridgeport (Brdg), Carson Linement (CarL), Little Valley (LitV), Mason (Masn), Petrified Springs (PetS), Smith Valley (SmtV), Wassuks (Wass), Wabuska (Wbsk), Olinghouse Opton (OlOp).

Publications associated with this dataset can be found at NCALM's Data Tracking Center

This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data.

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP) to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats and geology within the 3-nautical-mile limit of California's State Waters. CSMP has divided coastal California into 110 map blocks, each to be published individually as United States Geological Survey Open-File Reports (OFRs) or Scientific Investigations Maps (SIMs) at a scale of 1:24,000. Maps display seafloor morphology and character, identify potential marine benthic habitats and illustrate both the seafloor geology and shallow (to about 100 m) subsurface geology. Data layers for bathymetry, bathymetric contours, acoustic backscatter, seafloor character, potential benthic habitat and offshore geology were created for each map block, as well as regional-scale data layers for sediment thickness, depth to transition, transgressive contours, isopachs, predicted distributions of benthic macro-invertebrates and visual observations of benthic habitat from video cruises over the entire state. This coverage can be used to to aid in assessments and mitigation of geologic hazards in the coastal region and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore. These data are intended for science researchers, students, policy makers, and the general public. This information is not intended for navigational purposes.The data can be used with geographic information systems (GIS) software to display geologic and oceanographic information.

Introduction

The SCEC Community Fault Model (CFM) is an object-oriented, three-dimensional representation of active faults in southern California and adjacent offshore basins (Plesch et al., 2007). This latest update of the model includes 442 individually named fault representations in the preferred model with 1188 total representations including alternative representations. For the preferred fault set (442 surfaces), each fault object consists of triangulated surface representations (t-surfs) in several resolutions, fault traces in several standardized file formats, and complete metadata including references used to constrain the surfaces. The CFM faults are defined based on all available data including surface traces, seismicity, seismic reflection profiles, well data, geologic cross sections, and various other types of data and models. The CFM serves the Southern California Earthquake Center (SCEC) as a unified resource for physics-based fault systems modeling, strong ground-motion prediction, and probabilistic seismic hazards assessment (e.g., UCERF3). Together with the Community Velocity Model (CVM-H 15.1.0), the CFM comprises SCEC's Unified Structural Representation of the Southern California crust and upper mantle (Shaw et al., 2015).

Current Model Version: CFM5.3

The latest release of the CFM is version 5.3, which includes many new and revised fault representations, notably in the Ridgecrest and offshore regions (e.g., Nicholson et al., 2019, Plesch et al., 2020). In addition, the new model has greatly expanded and improved the metadata component of CFM to help ensure the internal consistency and maintainability of the model. Automated scripts now check for consistency with filenames and the various metadata components. CFM fault objects follow a hierarchical naming system that enables model users to easily sort the model by region and subregions. The expanded metadata now includes fault surface areas, area-weighted average strike/dip values, expected sense of slip, and references for each fault object. Additionally, the expanded metatdata includes the equivalent USGS Quaternary fault (Qfault) ID, when available. See the README.txt file in the root directory of the archive for information about the directory structure and contents of the entire zipped archive.

Directory Structure and Contents

doc/
Documentation and metadata, which includes an Excel spreadsheet with detailed metadata about each fault surface, an image showing a perspective view of the CFM5.3 model. All faults contain references to the works that helped to define the 3D fault surface geometry. Additional information about the metadata columns is provided in doc/README.txt

obj/native/
The CFM5.3 preferred fault surfaces in gocad tsurf format using the native mesh. The native mesh uses a variable mesh resolution. Smaller triangles generally indicate where a fault is well-constrained by data. All tsurf files are provided in UTM zone 11S using the NAD27 datum.

obj/500m/
The CFM5.3 preferred fault surfaces with a semi-regularized mesh of ~500m resolution in gocad tsurf format, UTM zone 11S NAD27 datum.

obj/1000m/
The CFM5.3 preferred fault surfaces with a semi-regularized mesh of ~1000m resolution in gocad tsurf format, UTM zone 11S NAD27 datum.

obj/2000m/
The CFM5.3 preferred fault surfaces with a semi-regularized mesh of ~2000m resolution in gocad tsurf format, UTM zone 11S NAD27 datum.

obj/alt/
Alternative CFM5.3 fault representations not included in the preferred model in gocad tsurf format, UTM zone 11S NAD27 datum. These alternative representations are provided in the native mesh where smaller triangles generally indicate areas of the surface that are well-constrained by data.

obj/traces/
Fault traces and upper tip lines (for blind faults) of the CFM5.3 preferred faults. While the CFM5.3 is a 3D model, it is often useful to make map-based visualizations of the model. The traces and blind faults are provided in several different formats in the subdirectories described below.

obj/traces/gmt/
Fault traces and blind faults in Generic Mapping Tools multisegment ASCII format (i.e. plain text).
.lonLat - Longitude/Latitude coordinates (WGS84 datum)
.utm - UTM zone 11S (NAD27 datum)

obj/traces/kml/
Fault traces and blind faults in GoogleEarth .kml format (WGS84 datum).
The kml files also contain metadata, which pops up if a fault is clicked on in GoogleEarth.

obj/traces/shp/
Fault traces and blind faults in GIS shapefile format (WGS84 datum).

References

Nicholson, C., Plesch, A., Sorlien, C. C., Shaw, J. H., Marshall, S. T., & Hauksson, E. (2019). Continued Updates, Expansion and Improvements to the Community Fault Model (CFM version 5.3). Poster Presentation at 2019 SCEC Annual Meeting. SCEC Contribution #9509.

Plesch, A., J. H. Shaw, C. Benson, W. A. Bryant, S. Carena, M. L. Cooke, J. F. Dolan, G. Fuis, E. Gath, L. Grant, E. Hauksson, J. H. Jordan, M. J. Kamerling, M. Legg, S. C. Lindvall, H. Magistrale, C. Nicholson, N. Niemi, M. Oskin, S. Perry, G. Planansky, T. K. Rockwell, P. Shearer, C. Sorlien, M. P. Süss, J. Suppe, J. Treiman and R. Yeats (2007). "Community Fault Model (CFM) for Southern California." Bulletin of the Seismological Society of America 97: 1793-1802. https://doi.org/10.1785/0120050211.

Plesch, A., Marshall, S. T., Nicholson, C., Shaw, J. H., Maechling, P., Su, M-H. (2020). “The Community Fault Model version 5.3 and new web-based tools” Virtual Poster Presentation at the 2020 SCEC Annual Meeting. SCEC Contribution 10547.

Shaw, J. H., Plesch, A., Tape, C., Suess, M., Jordan, T. H., Ely, G., Hauksson, E., Tromp, J., Tanimoto, T., Graves, R., Olsen, K., Nicholson, C., Maechling, P. J., Rivero, C., Lovely, P., Brankman, C. M., & Munster, J. (2015). Unified Structural Representation of the southern California crust and upper mantle. Earth and Planetary Science Letters, 415, 1-15. doi: 10.1016/j.epsl.2015.01.016. SCEC Contribution 2068.

This line shapefile represents fault lines in the offshore region of Point Reyes, California, Faults in the Point Reyes map area are identified on seismic-reflection data based on abrupt truncation or warping of reflections and (or) juxtaposition of reflection panels with different seismic parameters such as reflection presence, amplitude, frequency, geometry, continuity, and vertical sequence. The Point Reyes Fault Zone runs through the map area and is an offshore curvilinear reverse fault zone with predominantly north-side-up motion (Hoskins and Griffiths, 1971; McCulloch, 1987; Heck and others, 1990; Stozek, 2012) that likely connects with the western San Gregorio fault further to the south (Ryan and others, 2008), making it part of the San Andreas Fault System. The Point Reyes Fault Zone is characterized by a 5 to 11 km-wide zone of deformation in the shallow subsurface that is associated with two main fault structures, the Point Reyes Fault and the western Point Reyes Fault. Near the Point Reyes headland, vertical displacement of granitic basement across the Point Reyes Fault is at least 1.4 km (McCulloch, 1987). Offshore Double Point, vertical displacement on the Point Reyes Fault is difficult to assess because subsurface age constraints from nearby wells are lacking, and there are few offset horizons across the fault imaged on available seismic data. However, warping and folding of Neogene strata are clearly visible on high-resolution seismic data . The western Point Reyes Fault is defined by a broad anticlinal structure visible in both industry and high-resolution seismic datasets that exhibits that same sense of vergence (north-side-up) as the Point Reyes Fault. Faults were primarily mapped by interpretation of seismic reflection profile data (see field activity S-8-09-NC). The seismic reflection profiles were collected in 2009. The map that show these data are published in Open-File Report 2015-1114, "California State Waters Map Series—Offshore of Point Reyes, California." This layer is part of USGS Data Series 781.

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP) to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats and geology within the 3-nautical-mile limit of California's State Waters. CSMP has divided coastal California into 110 map blocks, each to be published individually as United States Geological Survey Open-File Reports (OFRs) or Scientific Investigations Maps (SIMs) at a scale of 1:24,000. Maps display seafloor morphology and character, identify potential marine benthic habitats and illustrate both the seafloor geology and shallow (to about 100 m) subsurface geology. Data layers for bathymetry, bathymetric contours, acoustic backscatter, seafloor character, potential benthic habitat and offshore geology were created for each map block, as well as regional-scale data layers for sediment thickness, depth to transition, transgressive contours, isopachs, predicted distributions of benthic macro-invertebrates and visual observations of benthic habitat from video cruises over the entire state. This coverage can be used to to aid in assessments and mitigation of geologic hazards in the coastal region and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore. These data are intended for science researchers, students, policy makers, and the general public. This information is not intended for navigational purposes.The data can be used with geographic information systems (GIS) software to display geologic and oceanographic information.