SCEC Community Fault Model (CFM)

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.