Introduction

The Statewide California Earthquake Center (SCEC) Community Fault Model (CFM) is an object-oriented, fully three-dimensional geometric representation of active faults in California and adjacent offshore basins. For each fault object, the CFM provides triangulated surface representations (t-surfs) in several resolutions, fault traces in several different file formats (shape files, GMT plain text, and GoogleEarth kml), and complete metadata including references used to constrain the surfaces. The CFM faults are defined based on 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 SCEC as a unified resource for physics-based fault systems modeling, strong ground-motion prediction, probabilistic seismic hazards assessment (e.g., the USGS National Seismic Hazard Model), and many other uses. 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: CFM 7.0

The current version of the SCEC CFM is version 7.0 (CFM 7.0), which builds on the previous CFM releases and serves as the latest update to Plesch et al. (2007). CFM 7.0 is a significant update as this is the first CFM to cover the entire state of California, spanning the Pacific-North American plate boundary from northern Mexico to the southern Cascadia subduction zone. This latest version has no changes to the southern California portion of the model, but now includes 113 new fault representations in central and northern California in the preferred model. These new central and northern California fault representations will undergo a community evaluation in 2024-2025, therefore, the central and northern California faults should be considered preliminary representations.

CFM 7.0 contains three fully-documented sub models: preferred, ruptures, and alternatives. In total, CFM 7.0 comprises the following components: 

1. CFM 7.0 Preferred: A set of 556 fault objects that constitute the preferred set of active faults. These faults have attained preferred status based on past community evaluations or are new representations.

2. CFM 7.0 Ruptures: A set of 13 fault objects assembled from the CFM 7.0 preferred model that ruptured during selected significant historic events. These are not earthquake source models, but are representations of the entire fault surfaces where a significant historic rupture occurred. This model is intended to indicate which CFM fault objects were involved with selected significant historic ruptures.

3. CFM 7.0 Alternatives: A set of 39 alternative representations where structural differences have been proposed that could potentially significantly impact fault mechanics and associated seismic hazards. These alternative representations were selected based on community rankings following a comprehensive evaluation of the CFM that took place in May of 2022.

Including all sub models, the CFM 7.0 incorporates 608 fully-documented fault objects. If you use the CFM, we would appreciate you citing both Plesch et al. (2007) and the DOI where the archive is stored.

Directory Structure and Contents of the CFM Archive

The CFM archive directory structure is as follows:

doc/
Documentation and metadata, which include an MS Excel spreadsheet with detailed metadata about each fault surface. Metadata for the preferred, rupture, and alternative models are provided in separate but otherwise identically formatted sheets within the file. All faults contain references to the works that helped to define the 3D fault surface geometry. More information about the metadata columns is provided in doc/README.txt

obj/preferred/
obj/ruptures/
obj/alternatives/
These directories contain the model components for the preferred, rupture, and alternative models, respectively. Each model contains an identical directory structure, which is described below using the preferred model as an example.

obj/preferred/native/
The CFM 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 11 using the NAD27 datum (EPSG:26711).

obj/preferred/500m/
The CFM preferred fault surfaces with a semi-regularized mesh of ~500m resolution in gocad tsurf format. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711).

obj/preferred/1000m/
The CFM preferred fault surfaces with a semi-regularized mesh of ~1000m resolution in gocad tsurf format. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711).

obj/preferred/2000m/
The CFM preferred fault surfaces with a semi-regularized mesh of ~2000m resolution in gocad tsurf format. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711).

obj/preferred/traces/
Fault traces and upper tip lines (for blind faults) of the CFM preferred faults. While the CFM 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 described below.

obj/preferred/traces/gmt/
Fault traces and blind faults in Generic Mapping Tools multiple segment file ASCII format (i.e., plain text).
  .lonLat - Longitude/Latitude coordinates (WGS84 datum)
  .utm    - UTM zone 11 NAD27 datum (EPSG:26711)

obj/preferred/traces/kml/
Fault traces and blind faults in Google Earth .kml format (WGS84 datum). The kml files also contain selected metadata as attributes which can be imported into QGIS. When a fault trace is clicked on in the Google Earth interface, a mini-webpage with metadata information will pop up.

obj/preferred/traces/shp/
Fault traces and blind faults in GIS shapefile format (longitude/latitude coordinates, WGS84 datum).

CFM Contributors

The current and past versions of the CFM would not be possible without contributions from numerous SCEC community members. We would like to thank the following CFM contributors:

Christine Benson, William Bryant, Sara Carena, Michele Cooke, James Dolan, Jessica Don, Gary Fuis, Eldon Gath, Russell Graymer, Judith Hubbard, Susanne Janecke, Sam Johnson, Yuval Levy, Lisa Grant Ludwig, Egill Hauksson, Thomas Jordan, Marc Kamerling, Keith Knudsen, Mark Legg, Scott Lindvall, Harold Magistrale, James Lienkaemper, Scott Marshall, Craig Nicholson, Nathan Niemi, Stu Nishenko, Michael Oskin, Sue Perry, George Planansky, Andreas Plesch, Thomas Rockwell, David Schwartz, John Shaw, Peter Shearer, Bob Simpson, Christopher Sorlien, M. Peter Süss, John Suppe, Jerry Treiman, Jeff Unruh, Janet Watt, Franklin Wolfe, Chris Wills, Robert Yeats, and every colleague that has participated in a CFM community evaluation. We could not make the CFM without this community effort.

CFM Evaluators

Before assembling CFM 6.0 and subsequently CFM 7.0, a team of SCEC colleagues participated in a rigorous evaluation of CFM 5.3 in April-May of 2022. This evaluation was open to the SCEC community and focused on 23 critical fault representations where different proposed interpretations have the potential to significantly affect seismic hazards. This evaluation resulted in 14 new fault representations in the CFM 6.0 preferred model. The lower ranked representations are now provided in the CFM alternatives. We would like to thank the following CFM evaluators for volunteering their time and expertise to this process:

Sinan Akçiz, Sara Carena, Michele Cooke, Tim Dawson, Jessica Don, Austin Elliot, Erik Frost, Gary Fuis, Athanassios Ganas, Eldon Gath, Alex Hatem, Susanne Janecke, Marc Kamerling, Christodoulos Kyriakopoulos, Mark Legg, Karen Luttrell, Chris Madugo, Scott Marshall, Andrew Meigs, Craig Nicholson, Nate Onderdonk, Alba Rodríguez Padilla, Andreas Plesch, Kate Scharer, John Shaw, Chris Sorlien, Franklin Wolfe, Doug Yule, Judy Zachariasen.