The purpose of compiling the CEUS-SSC Project database was to organize and store those data and resources that had been carefully and thoroughly collected and described for the TI Team’s use in characterizing potential seismic sources in the CEUS. An important goal for the development of this database was to document sources and dates for all information that was initially assessed for the CEUS-SSC Project, specifying exactly what data and resources were considered, and provide for pertinent future data sets to be incorporated as they were generated for the project.

Development of the project database began at the inception of the project to provide TI Team members with a common set of data, maps, and figures for characterization of potential seismic sources. The database was continually updated during the course of the project through the addition of new references and data collected by TI Team members and project subcontractors, including information presented in project workshops and provided through PPRP review documentation. 

This appendix presents the contents of the project database, as well as information on the workflow, development roles, database design considerations, data assessment tasks, and management of the database. Based on the CEUS Project Plan, the project database included, but was not limited to, the following general types of data:

  • Magnetic anomaly
  • Gravity anomaly
  • Crystalline basement geology
  • Tectonic features and tectonic/crustal domains
  • Tectonic stress field
  • Thickness of sediments
  • Crustal thickness
  • VP at top of crystalline basement
  • Seismic reflection data at Charleston, South Carolina
  • Earthquake catalog
  • Quaternary faulting and potential Quaternary features
  • Mesozoic rift basins
  • Paleoliquefaction sites
  • Topography and bathymetry
  • Liquefaction dates from published literature for the Wabash, New Madrid, and Charleston seismic zones
  • Index map showing locations of published crustal scale seismic profiles and geologic cross sections

A table describing digital data layers included in the project database is presented at the end of this appendix (Table A-1), along with metadata summary sheets for each of the CEUS-scale data layers (Sheets A-1 through A-31).


A.1 Data Sources

The compilation and documentation of spatial geologic, seismic and geophysical data for the CEUS-SSC Project required significant and continual effort to ensure that the geographic information system (GIS) data provided accurate and up-to-date information for use in seismic source characterization. Digital data were compiled from sources in the public domain, professional literature, private domain data developed as part of nuclear licensing activities, and available data in the academic sector. The database is designed to be available to the public for further use in seismic source zone characterization and assessment.

Digital data collection efforts focused on the CEUS-SSC study area (Figure A-65, Sheet A-23). Digital and nondigital data were collected from a wide range of sources. For example, some data sets pertain to the conterminous United States (e.g., magnetic or gravity data), while others pertain to only a localized study area (e.g., paleoliquefaction studies). Digital data were not typically limited to the CEUS-SSC study area extent unless it was necessary to reduce the file size of large data sets. In general, only selected features deemed to be the most pertinent were digitized from nondigital data.

Several new data layers were compiled specifically in support of this project and are included in the project database. These new data layers include the following information sets:

  • Earthquake catalog (see Appendix B)
  • Magnetic anomaly data
  • Gravity anomaly data
  • Paleoliquefaction features (see Appendix E)
  • Mesozoic rift basins within the ECC-AM
  • Maximum horizontal compressive stress data

A.2 Project Database Design and Management

The project database was compiled with input from the TI team, project subcontractors, and PPRP members. The GIS software used in the development of the database was Environmental Systems Research Institute’s (ESRI) ArcGIS versions 9.3 and 9.3.1. The project database was compiled, maintained, and made available to team members on a server in the Fugro William Lettis & Associates (FWLA) Walnut Creek, California, office. Table A-1 presents the contents of the project database organized by the CEUS-SSC study area, seismotectonic zone, and RLME zone. Subfolders organize data within these folders according to their similar subject matter or data theme. 

The file-naming convention used in the project database allows for the quick identification of data type, geographic coverage, and author. For example, in the file name:

ROI_FeatureType_AuthorDate_Rev#.<file type suffix>

where ROI is the region of interest or source zone (e.g., CEUS, AHEX); Feature Type is the type of feature represented (e.g., GRAV for gravity; PL for paleoliquefaction features); Author Date is the author or organization and the year of publication; and Rev# is the revision number.

All project data began at revision 0 (R0) at the completion of this project and will be updated with consecutive revision numbers as the data are updated. Updated data will be made available via the project website as discussed in Section A.6. Providing a full file name reference allows data to be identified if removed from the organization of the project database.

During the course of the project, data were made available to TI Team members via a file transfer protocol (FTP) server established for the project in the FWLA Walnut Creek office. TI Team members were provided individual passwords to access the secured server. Updates to the project FTP server were provided by the project Database Manager.


A.3 Workflow and Data Assessment

Data were compiled by a staff of several geologists and analysts for CEUS-scale data. Processed and documented data were forwarded to the project Database Manager for inclusion in the database. Data were received in digital and nondigital forms. Digital data were in a GIS format compatible with ESRI’s ArcGIS software, ASCII-delimited text files; databases, spreadsheets, or CAD layers. Nondigital data included hard copy drawings, maps, or other documents, including scans of hard-copy documents. The workflow and processes for compiling and documenting digital and nondigital data are outlined in the following sections.


A.3.1 Workflow

Project GIS data were collected by several TI Team members and the PPRP during the course of the project. Once received by the project Database Manager, data were reviewed prior to incorporation into the project database. Versions of data layers were indicated to show when updates were completed. Project data were stored on a replicated, secure server. All data were backed up on a weekly basis to provide an off-site archive of project data.


A.3.2 Digital Data

Digital data published by the USGS and other sources comprise a significant portion of the project database. Digital data were collected in various ESRI GIS-compatible formats for vector and raster data (shapefile, coverage, GRID, ArcInfo Interchange, and personal and file geodatabase formats) or in ASCII-delimited text formats. All data received were reviewed to assess, at a minimum, the following factors:

  • Completeness of the data
  • Accompanying metadata, including completeness of documentation, source information, compilation scale
  • Defined coordinate system
  • Topological integrity

Compiled data were not altered beyond any routine conversion or coordinate transformation required for uploading to the project database. Example conversions include converting data from a different GIS or CAD format, projecting data from the source coordinate system into the project coordinate system, transforming the horizontal and vertical datum, and converting from ASCII-delimited text format to the project data format.

Occasionally, data were incorporated into the project database without alteration or renaming from the source data. For example, data that comprise the GIS layers of the Geologic Map of North America (Figure A-5) retain their original file names as provided on the USGS’s website (, although they have been converted from the ESRI file geodatabase format to the ESRI shapefile format. Metadata accompanying the data in the project database contain information informing the user of what data are contained in each layer.


A.3.3 Nondigital Data

Some geologic or geophysical data requested for use in the CEUS-SSC Project were provided in a nondigital format, including hard copy documents such as maps and figures in reports or research papers. GIS data created from these nondigital data formats underwent a review process to ensure data quality. The assessment was performed in the following review stages:

1. Review by the originating GIS analyst
2. Review by the geologist or analyst requesting the data
3. Review by the project Database Manager prior to submission to the project database

The review of GIS data layers that were produced from nondigital data involved the following steps:

  • Visual inspection by comparison to source hardcopy documents
  • Check of coordinate reference system
  • Completion of metadata
  • Development of database attributes for each layer, as appropriate
  • Check for complete topology (spatial adjacency), as appropriate

For both digital and nondigital sources of data, scale is a significant consideration in the use of the project database. The consideration of the scale of data allows for the assessment of positional accuracy. Each data layer in the database contains in the accompanying metadata a notation about the scale at which the data were referenced or collected. For example, for vector data, a line that was digitized at a scale of 1:100,000 will have a greater positional accuracy than the same line digitized at a scale of 1:1,000,000. The scale of source information varies significantly in the project database. Whenever data are digitized based from hard-copy maps, error can be introduced. Although a GIS allows the display of data at any scale specified by the user, the accuracy of the same data will not change. Therefore, using digital data at a larger scale than that of the original source will not produce a more accurate map. When the layers in the project database are used, the source scale must be considered. In the course of developing this database, data were digitized at scales the same as, or larger than, that of the source to limit the error introduced through the digitization process.


A.4 Use of Project Database in Model Development

The project database (Table A-1) comprises many different types of data that were useful to the TI Team and PPRP members for understanding seismic, geologic, and geophysical conditions and for development of the seismic source model. The database includes geologic, geophysical, geodetic, seismic, tectonic, geomorphic, and earthquake information.

The project database was made available to TI and PPRP team members during the course of the project. During project working meetings, elements of the database were projected on a screen to facilitate discussions. TI Team GIS analysts were available to display elements of the project database at the request of TI Team members. For example, using a GIS, various types of requested data layers were shown for a particular area to identify geologic relationships. Team member inputs were gathered in real time during these discussions through the drawing of features into the GIS display. These features could then be incorporated into the seismic model immediately afterward.

A.5 Metadata

Metadata were compiled for each GIS data layer. All source reference documents used in preparing the data layer were noted to allow contributing data layers to be cited in future applications of the data. Additional primary documentation includes scale of the sources used, the scale at which the data were digitized and appropriate scales of use, coordinate reference system, and attribute library and domains. Metadata conform, wherever possible, to the Content Standard for Digital Geospatial Metadata established by the  Federal Geographic Data Committee (FGDC). This metadata standard is currently used by federal agencies for documenting geospatial data.

Included in this appendix are metadata summary sheets that present information for each data layer that covers the CEUS study area or similar regional coverage (Sheets A-1 through A-31). These one- and two-page sheets serve as quick references that summarize the data, the source of the data, the original publisher, the source and converted data formats, and disclaimers or noted constraints on the use of the data. Accompanying each summary sheet is a figure depicting the data in the CEUS-SSC study area, often with topography and state boundaries provided for reference. More local data derived from detailed studies have also been included in the database. These local data sets typically include features digitized from a figure in a publication or other published map. However, metadata summary sheets have not been developed for these large-scale data layers. All data layers and their accompanying metadata summary sheets (as appropriate) are listed in Table A-1.


A.6 Database Delivery Format

The project database includes both vector and raster data formats. Vector data formats represent features as points, lines, or polygons. Each type of vector class is suited for different types of features (i.e., points for spot features such as measurement locations, lines for features such as topographic contours, and polygons for area features such as mapped geologic units). A raster data format represents surfaces where each regularly spaced interval contains a discrete value. A digital elevation model (DEM) is an example of raster data.

The project database contains vectors and rasters depending on the type of data compiled. A goal of the project database was to make the data accessible to a large audience with minimal effort. The ESRI shapefile data format was selected for vector features because of the ubiquitous use of ESRI’s ArcGIS software and the large number of other GIS software in use that can import this format. Raster data were compiled in a GeoTIFF format for similar reasons. 

All data in the project database are provided in geographic (latitude/longitude) decimal degree coordinates using the North American Datum of 1983 (NAD83). This coordinate system can be read by nearly all GIS software packages and reprojected as necessary into other coordinate systems. As noted in Section A.3.2, data compiled from existing sources were provided in various coordinate systems. These data were reprojected as necessary to geographic coordinates on NAD83.

The database will be available on the CEUS-SSC Project website ( and will include the earthquake catalog plus all magnetic, gravity, and stress data compiled for the project. The CEUS-SSC report, including all appendices, will also be provided on the website. All data are provided in a format that will allow other investigators to use the outputs of the CEUS-SSC Project model for subsequent seismic hazard assessments. A more complete description of the CEUS-SSC website is provided in Section 9.3.3 of the report.

CEUS-SSC Project Website