DIGITAL DATABASE OF FAULTS FROM THE FAULT ACTIVITY MAP OF CALIFORNIA AND ADJACENT AREAS
COMPILATION AND INTERPRETATION BY CHARLES W. JENNINGS1 WITH ASSISTANCE FROM GEORGE J. SAUCEDO1
DIGITAL REPRESENTATION BY RICHARD L. DART2, MICHAEL N. MACHETTE2, DIANE BURNS1, GEOFFREY D. FANEROS1, JASON D. LITTLE1, and JENNIFER R. DAVIS1
CALIFORNIA DEPARTMENT OF CONSERVATION DIVISION OF MINES AND GEOLOGY 801 K Street MS 12-31 Sacramento, CA 95814
1. California Department of Conservation Division of Mines and Geology 2. U.S. Geological Survey
LICENSE AGREEMENT
(c) California Department of Conservation, Division of Mines and Geology, 2000. All rights reserved. No part of this CD-ROM may be reproduced, transmitted, or distributed in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of the Division of Mines and Geology except as follows. Permission is granted to produce plots of all or part of the data under the following conditions:
1) Personal use. 2) For publication in a report in unmodified form; cite on figure or text as "Reproduced with permission, Division of Mines and Geology, CD-ROM 2000-00x (2000), Digital database of faults from the Fault Activity Map of California and Adjacent Areas.
3) For publication in a report, in modified form, cite on figure or in text as "Modified from, Division of Mines and Geology, CD-ROM 2000-00x (2000), Digital database of faults from the Fault Activity Map of California and Adjacent Areas.
Introduction
The digital database contains the faults shown on the Fault Activity Map of California and Adjacent Areas by Charles W. Jennings published in 1994. Many faults in Nevada and Baja California shown on the published map are not in this digital database. The base map consists of two files, one containing the outline of California and the other containing the state boundary and county boundaries. The faults were digitized at the samescale as the published map, 1:750,000 or 1 inch equalsapproximately 12 miles. The theoretical accuracy of the publishedmap is about the 0.012-inch width of the fault lines, which isequivalent to 232 meters (760 feet) on the ground. However,plotting and drafting errors can and do significantly increasethe uncertainty. For example, a plotting error of a line width at1:750,000 scale could cause a location error of 464 meters(approximately 1392 feet) on the ground. The user is cautionedthat this database is not suitable for site-specific applicationsnor is it to be confused with Earthquake Fault Zone Maps orSeismic Hazard Zone Maps.
2 This database should be used in conjunction with the published version of the Fault Activity Map of California and Adjacent Areas available from the California Department of Conservation, Division of Mines and Geology (DMG) by mail: P.O. Box 2980 Sacramento, CA 95812-2980 or by phone (916) 445-5716. The map is also available from DMG offices in San Francisco (415) 904-7707 and Los Angeles (213) 239-0878.
The database currently is available in ARC/INFO and MAPINFO formats. Future versions of the database may include additional information, such as the fault parameters used in the Probabilistic Seismic Hazard Assessment for the State of California (DMG OFR 96-08).
Accuracy and Limitations of this Database
This database is a faithful digital representation of most faults on the Fault Activity Map of California and Adjacent Areas. Users of this database should be aware of the difference between precision and accuracy. While digital data can be reproduced precisely at any scale, the accuracy of the data remains constant. As the scale is increased from 1:750,000, uncertainty and errors in fault location remain the same. (See discussion of errors in the Introduction.) There are discrepancies between the location of faults in this database and those depicted on the 1:750,000-scale Geologic Map of California because the faults were redrafted onto new base maps. Also the user is cautioned that the faults in this database are not necessarily the same as those depicted on the 1:24,000-scale DMG Earthquake Fault Zone Maps. Although the author of the Fault Activity Map attempted to make the fault map consistent with the Earthquake Fault Zone Maps, the evaluation criteria for the maps are different so the depiction of faults may differ significantly.
Faults in the Fault Activity Map and Geologic Map of California Databases
Fault locations in the digital databases for the Fault Activity Map and the Geologic Map of California are similar but not identical. The representation of faults in the digital database for the Geologic Map of California is the same as those of the Fault Map of California, published in 1975 (Jennings, 1985 p.56). Faults depicted on the Fault Activity Map of California and Adjacent Areas, published in 1994, were revised using the results of 20 years of research conducted since the earlier publication. The new map was redrafted and scribed on a new edition of the 3 base map, which is significantly different from the previous version. Faults in the database for the Fault Activity Map are those of the 1994 map. Although the differences are not readily apparent on the printed versions of the maps, differences, particularly in location, will be obvious if the digital versions of the faults are superimposed. See Division of Mines and Geology Bulletin 201 (Jennings,1985) and An Explanatory Text to Accompany the Fault Activity Map of California and Adjacent Areas (Jennings,1994) for more information on the sources of the datasets.
Digital Compilation
This data set was created by scanning the 1:750,000-scale mylar overlays of the faults shown on Jennings (1994)using ARC/INFO software. Scanning, vectorization, and initial editing of the Quaternary faults were done by Richard Dart and Michael Machette of the U.S. Geological Survey in Denver. Additional editing was done by Diane Burns and Geoffrey Faneros of DMG in Sacramento. The pre-Quaternary faults were digitized by Geoffrey Faneros and Jason Little of DMG. The late Cenozoic faults in the Foothills Fault Zone are included with the pre-Quaternary faults and were digitized by Jennifer Davis of DMG. George Saucedo and David Wagner of DMG did proofing of both the initial and the final editing.
Base Maps
The base map in this database was produced all or in part from a county boundary file by the U.S. Bureau of Reclamation (1992). The county boundaries were digitized from standard USGS 1:24,000- scale topographic maps and the master file is maintained by the Teale Data Center.
Database Contents
ARC/INFO
The digital database consists of five ARC coverages representing the five subdivisions of the faults. These coverages have been converted into ARC/INFO uncompressed export files (.e00) and must be converted by the user into ARC coverages using the import command.
4 ARC/INFO Description of Coverage export file
Historic.e00 Faults with historic displacement Holocene.e00 Faults with Holocene displacement Latequat.e00 Faults with late Quaternary displacement Quat.e00 Faults with Quaternary displacement Prequat.e00 Faults with pre-Quaternary displacement
There are two additional ARC coverages containing base materials:
Statemap.e00 California state boundary County.e00 California county boundaries
ARC/INFO Database Specifics Map Projection
PROJECTION -Lambert Conformal Conic UNITS METERS -on the ground SPHEROID -Clarke 1866 1st STANDARD PARALLEL 33° 2nd STANDARD PARALLEL 45° CENTRAL MERIDIAN -119° LATITUDE OF ORIGIN 0°
Field Definition Terms
ITEM NAME name of the database field (item) WIDTH maximum number of digits or characters stored OUTPUT output width TYPE B-binary integer, F-binary floating point number, I-ASCII integer, C-ASCII character string N.DEC. number of decimal places maintained for floating point numbers
Contents of the Arc Attribute Tables (.AAT)
ITEM NAME WIDTH OUTPUT TYPE N.DEC
FNODE# 4 5 B - starting node of arc
5 (from node) TNODE# 4 5 B - ending node of arc (to node) LPOLY# 4 5 B - polygon to the left of the arc RPOLY# 4 5 B - polygon to the right of the arc LENGTH 4 12 F 3 length of arc in meters
LVALUE 3 3 I - line value
Line Types Recorded in the LTYPE Field
on land solid -well located dashed -approximately located or inferred dotted -concealed
offshore solid -well defined dashed -inferred
Line Values Recorded in the LVALUE Field
1 -solid 2 -dashed 3 -dotted
MAPINFO The digital database consists of MAPINFO.TAB files representing the subdivisions of faults for California and their accompanying tic files.
6 These data have been converted into MAPINFO files from ARC/INFO uncompressed export files (.e00) using ARCLINK software.
MAPINFO Description of Files Files Historic_line.tab Faults with historic displacement Historic_tic.tab Tic marks Holocene_line.tab Faults with Holocene displacement Holocene_tic.tab Tic marks Latequat_line.tab Faults with late Quaternary displacement Latequat_tic.tab Tic marks Quat_line.tab Faults with Quaternary displacement Quat_tic.tab Tic marks Prequat_line.tab Faults with pre-Quaternary displacement Prequat_tic.tab Tic marks
There are two additional MAPINFO files containing base materials: Statemap_line.tab California state boundary Statemap_tic.tab Tic marks County_line.tab California county boundaries County_tic.tab Tic marks
MAPINFO Database Specifics Map Projection ROJECTION Regional Conformal Projection Conformal Projection (California) DATUM North American 1927 (NAD 27) UNITS Meters ORIGIN (Long) -119° ORIGIN (Lat) 0° STANDARD PARALLEL (1st) 33° STANDARD PARALLEL (2nd) 45° FALSE EASTING 0 FALSE NORTHING 0
The Lambert Conformal Conic projection listed in the MAPINFO projection file (MAPINFOW.PRJ) uses -96° and 23° as the Longitude and Latitude of origin, respectively (see below).
From MAPINFOW.PRJ: "--- Regional Conformal Projections ---"
"Conformal Projection (United States)", 3, 62, 7, -96, 23, 33, 45, 0, 0
7 A text editor can be used to edit or create a new projection file using the projection parameters for these files.
Example: "Conformal Projection (Fault Map)" 3, 62, 7, -119, 0, 33, 45, 0,0
For additional information on projections or creating your own coordinate system refer to the MapInfo Reference Manual.
Field Definition Terms
FIELDS names of the fields (columns) in table TYPE Character-alphanumeric character, Float-number stored in floating-point decimal form, Integer-Integer between -32,768 and +32,768 WIDTH number of characters stored in the field
MAPINFO TABLE STRUCTURE (for FAULTS)
FIELDS TYPE WIDTH
FNODE# Integer - starting node of arc (from node) TNODE# Integer - ending node of arc (to node) LPOLY# Integer - polygon to the left of the arc RPOLY# Integer - polygon to the right of the arc LENGTH Float - length of arc in meters
Line Types Recorded in the LTYPE Field on land solid -well located dashed -approximately located or inferred dotted -concealed offshore solid -well defined dashed -inferred 8 Line Values Recorded in the LVALUE Field
1 -solid 2 -dashed 3 -dotted
MAPINFO TABLE STRUCTURE (for TICS)
FIELD NAME TYPE WIDTH
IDTIC Integer - id number assigned to each tic XTIC Float - longitude of tic YTIC Float - latitude of tic
References cited
Jennings, C.W., 1985, An explanatory text to accompany the 1:750,000 scale fault and geologic maps of California: California Department of Conservation, Division of Mines and Geology Bulletin 201, 197 p.
Jennings, C.W., 1994, Fault activity map of California and adjacent areas: Department of Conservation, Division of Mines and Geology Geologic Data Map No. 6, scale 1:750,000.
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