U.S. DEPARTMENT OF THE INTERIOR
		        U.S. GEOLOGICAL SURVEY


                           PRELIMINARY MAPS OF
             QUATERNARY DEPOSITS AND LIQUEFACTION SUSCEPTIBILITY,
              NINE-COUNTY SAN FRANCISCO BAY REGION, CALIFORNIA:
                           A DIGITAL DATABASE


                                geology by

          Keith L. Knudsen(1,2), Janet M. Sowers(1), Robert C. Witter(1),
               Carl M. Wentworth(3) and Edward J. Helley(1)

                            digital database by

      Carl M. Wentworth(3), Robert S. Nicholson(3), Heather M. Wright(3), 
                         and Katherine M. Brown(3)




                         Open-File Report 00-444
                               Version 1.0



                                   2000





                            Author Affiliations
                    1 - William Lettis & Associates, Inc.
                    2 - California Division of Mines and Geology
                    3 - U.S. Geological Survey




This report is preliminary and has not been reviewed for conformity with U.S. 
Geological Survey editorial standards or with the North American Stratigraphic 
Code. Any use of trade, product, or firm names is for descriptive purposes only 
and does not imply endorsement by the U.S. Government.

This database, identified as 'Preliminary maps of Quaternary deposits and 
liquefaction susceptibility, nine-county San Francisco Bay region, California: a
digital database', has been approved for release and publication by the Director
of the USGS. Although this database has been reviewed and is substantially 
complete, the USGS reserves the right to revise the data pursuant to further 
analysis and review. This database is released on condition that neither the 
USGS nor the U.S. Government may be held liable for any damages  resulting from 
its use.


                                 INTRODUCTION

This report presents a preliminary map and database of Quaternary deposits and 
liquefaction susceptibility for the nine-county San Francisco Bay region, 
together with a digital compendium of ground effects associated with past 
earthquakes in the region. The report consists of (1) a spatial database of five
data layers (Quaternary deposits, quadrangle index, and three ground effects 
layers) and two text layers (a labels and leaders layer for Quaternary deposits
and for ground effects), (2) two small-scale colored maps (Quaternary deposits 
and liquefaction susceptibility), (3) a text describing the Quaternary map, 
liquefaction interpretation, and the ground effects compendium, and (4) this 
pamphlet. All parts of the report are digital; this pamphlet describes the 
database and digital files and how to obtain them by downloading across the 
internet.

The nine counties surrounding San Francisco Bay straddle the San Andreas fault 
system, which exposes the region to serious earthquake hazard (Working Group on 
California Earthquake Probabilities, 1999). Much of the land adjacent to the Bay
and the major rivers and streams is underlain by unconsolidated deposits that 
are particularly vulnerable to earthquake shaking and liquefaction of 
water-saturated granular sediment. Map delineation of the different types and 
ages of Quaternary deposits supports evaluation of susceptibility to 
liquefaction, the immediate application of the work, but serves many other 
purposes as well. It provides a framework for interpreting the architecture and 
history of the Quaternary sedimentary basins, which is used in estimating 
earthquake shaking and  modeling the groundwater system. The mapping is also 
useful in constraining the ages and histories of offsetting faults, in guiding 
geotechnical investigations, and in other engineering, geologic, and 
archeological applications.

This new map provides a modern and regionally consistent treatment of Quaternary
surficial deposits that builds on the pioneering mapping of Helley and Lajoie 
(Helley and others, 1979) and such intervening work as Atwater (1982), Helley 
and others (1994), and Helley and Graymer (1997a and b). Like these earlier 
studies, the current mapping uses geomorphic expression, pedogenic soils, and 
inferred depositional environments to define and distinguish the map units. In 
contrast to the twelve map units of Helley and Lajoie, however, this new map 
uses a complex stratigraphy of some forty units, which permits a more realistic 
portrayal of the Quaternary depositional system. The two colored maps provide a 
regional summary of the new mapping at a scale of 1:275,000, a scale that is 
sufficient to show the general distribution and relationships of the map units 
but cannot distinguish the more detailed elements that are present in the 
database.

The report is the product of years of cooperative work by the USGS National 
Earthquake Hazards Reduction Program (NEHRP) and National Cooperative Geologic 
Mapping Program, William Lettis and & Associates, Inc. (WLA) and, more 
recently, by the California Division of Mines and Geology as well. An earlier 
version was submitted to the Geological Survey by WLA as a final report for a 
NEHRP grant (Knudsen and others, 2000). The mapping has been carried out by WLA 
geologists under contract to the NEHRP Earthquake Program (Grants 
#14-08-0001-G2129, 1434-94-G-2499, 1434-HQ-97-GR-03121, and 99-HQ-GR-0095) and 
with other limited support from the County of Napa, and recently also by the 
California Division of Mines and Geology. The current map consists of this new 
mapping and revisions of previous USGS mapping. 

The report is preliminary because, although much of the mapping is at a scale of
1:24,000, for a third of the region it is at 1:100,000, including much of the 
core area, and another fifth meets less than 75% of the mapping criteria for the
work (see part 3, Description of Mapping). Improvement of these parts of the map
is the topic of ongoing work.

The report consists of eight numbered parts that are represented by digital 
files, most of which are provided in two or three different formats. The parts 
and files are described in DATABASE CONTENTS (below), and their packaging for 
user access is described in Presentation (below). 

Parts 1, 2, and 3 are texts:
    1. this pamphlet, including description of the Quaternary deposits, ground
       effects, and quadrangle index databases;
    2. revision list, which lists the digital files as they are available over
       the Net and records version number and any revisions;
    3. description of mapping, including description of mapping techniques and
       Quaternary units, of  the liquefaction interpretation, and of the ground 
       effects compendium (two color figures).

Parts 4, 5, and 6 are digital spatial databases and associated text layers:
    4. Quaternary deposits and liquefaction susceptibility database: one   
       database layer, one text layer;
    5. ground effects database: three database layers (separate polygon layers 
       for historic and Loma Prieta effects), one text layer;
    6. quadrangle index database: one database layer.

Parts 7 and 8 are graphic plot files for map sheets 1 and 2 at a scale of 1:275,000:
    7. map sheet 1: plot file of the Quaternary deposits map, including an index
       of the status of mapping and an explanation of map units;
    8. map sheet 2: plot file of the liquefaction susceptibility map, including 
       ground-effects localities.

The two colored maps are presented as digital plot files in PostScript and PDF 
format (image size 33 x 36 inches each). The PostScript map images (28-30 MB) 
can be used for viewing or plotting in computer systems with sufficient 
capacity, and the considerably smaller PDF files (6 MB) can be viewed or 
plotted in full or in part from Adobe ACROBAT running on Mac, PC, or UNIX 
platforms. The appearance of the maps in plots (colors and line weights) will 
depend on file type and the particular plotter that is used. 

The five database layers are provided both as uncompressed ARC/INFO export files
in Version 7 format and as ArcView Shape files. The database layers consist of 
the Quaternary deposits layer (which includes ratings for liquefaction 
susceptibility), the index of 7.5-minute quadrangles (which includes ratings for
the status of mapping), and the three layers representing the compendium of 
earthquake ground effects. The label-and-leader text layers, which contain 
graphic elements, are provided only as uncompressed ARC/INFO export files. The 
full versatility of the spatial database is obtained by importing the ARC export
files into ARC/INFO or an equivalent GIS package. Other GIS packages, including 
MapInfo and ArcView, may use either the ARC export or Shape files, although the 
Shape files do not retain the definition tables and do not include the text 
layers. The information in the definition tables is also listed in this 
pamphlet.

The spatial database was compiled in vector form over the past several years 
with versions 6 through 7.2 of ARC/INFO, a commercial Geographic Information 
System (Environmental Systems Research Institute [ESRI], Redlands, California), 
using the menu interface ALACARTE (Fitzgibbon and Wentworth, 1991; Fitzgibbon, 
1991; Wentworth and Fitzgibbon, 1991), and with MapInfo for part of the 
ground-effects database. The map plot files were assembled as graphics files in 
ARC/INFO from the spatial database and then converted to PostScript and PDF 
formats.


                                Acknowledgements

Digital compilation of the many 7.5-minute quadrangles involved was carried out 
over a period of several years, during which one or more quadrangles each were 
digitized by Andrew Barron, Gregg Beukelman, Joe Colgan, Jennifer Davis, Scott 
Graham, Marjorie Lucks, Tom May, David Ramsey, Carrie Randolph, Joel Robinson, 
Adam Soule, and Jim Thordsen. Digital compilation of the 0.5X1degree quadrangles
was done separately for the reports by Knudsen and others (1997) and Sowers and 
others (1998).


                             DATABASE CONTENTS

The report consists of digital files representing the eight parts of the 
database, most of which are presented in more than one format. The names of the 
files are unique designators based on the report identifier, of00-444, followed 
by part numbers and an extension indicating file type. Some of the files have 
been bundled in tape archive files (tar files: .tar extension) and the larger 
ones have been compressed with gzip, yielding a final .gz extension (see 
Presentation, below). An AML script (import.aml) is provided that will assemble 
the coverages and definition files in ARC/INFO from the export files. The files 
and their identities are as follows:


    1. Open-File Pamphlet: The text of the open-file pamphlet (this text), which
       describes the database and how to obtain it.
          a. of00-444_1a.txt   ASCII file, 0.06 MB.                  
          b. of00-444_1b.ps   PostScript file, 0.8 MB.
          c. of00-444_1c.pdf   PDF file, 0.08 MB  

    2. Revision List: A list of the parts of the report (including bundled 
       packages of parts), indication of the current version number
       for the report and in which version each part was last revised (if at 
       all), followed by a chronologic list describing any revisions (see 
       REVISIONS, below).
          a. of00-444_2a.txt     ASCII file                                     

    3. Description of Mapping: A 60-page text (two color figures) that describes
       the Quaternary deposits of the region, the 40 map units plus their 
       subdivisions, the estimates of liquefaction susceptibility, the ground 
       effects compendium, and the techniques and history of the work.
          a. of00-444_3a.txt   ASCII file, 0.2 MB. (No figures are included.)
          b. of00-444_3b.ps   PostScript file, 8.2 MB
          c. of00-444_3c.pdf   PDF file, 1.0 MB
 
    4. Quaternary Deposits and Liquefaction Susceptibility Database: The data   
       files representing the lines and polygons of the Quaternary deposits 
       layer and associated definition tables (ARC export and ArcView Shape 
       formats), and the annotation layer containing unit labels and leaders 
       (ARC export format only). Note that the definition tables within the ARC 
       coverage are not retained in the Shape files.
          a. of00-444_4a.e00.gz - Quaternary Deposits: a compressed ARC export 
                      coverage containing lines and polygons (11 MB, 
                      uncompresses to 46 MB). Import.aml will name this coverage
                      sf-quat.
          b. of00-444_4b.e00 - Annotation: ARC export coverage containing unit 
                      labels and leaders (0.4 MB) scaled for graphic  display at 
                      1:275,000. Import.aml will name this coverage sf-qanno.
          c. of00-444_4c.tar.gz - Quaternary Deposits: ArcView line and polygon 
                      Shape files bundled as one compressed tar file (20 MB, 
                      uncompresses to 67 MB). When opened, the tar file yields:
                      - line files: sf-qlns.dbf, sf-qlns.shp, and sf-qlns.shx
                      - polygon files: sf-qpys.dbf, sf-qpys.shp, and sf-qpys.shx

    5. Ground Effects Database: The data files representing the points, lines, 
       and polygons of past earthquake ground effects (ARC export and ArcView 
       Shape formats), and the annotation layer containing station numbers and 
       leaders (ARC export format only).
          a. of00-444_5a.e00.tar.gz - Ground Effects: four ARC export coverages 
                      containing point, line, and polygon localities and  
                      station-number annotation and leaders for the historic and
                      Loma Prieta datasets, bundled as one compressed tar file 
                      (0.07 MB, uncompresses to 0.6 MB). When opened, the tar
                      file yields:
                      - of00-444_5a1.e00: ARC export file containing point and 
                        line localities for both the historic and Loma Prieta 
                        datasets. Import.aml will name this coverage sf-effects.
                      - of00-444_5a2.e00: ARC export file containing polygon 
                        localities for the historic dataset. Import.aml will 
                        name this coverage sf-efhspys.
                      - of00-444_5a3.e00: ARC export file containing polygon 
                        localities for the Loma Prieta dataset. Import.aml will 
                        name this coverage sf-eflppys.
                      - of00-444_5a4.e00: ARC export file containing 
                        station-number annotation and leaders for the whole 
                        effects  database scaled for graphic display at 
                        1:275,000 (1:100,000 for San Francisco). Import.aml will
                        name this coverage sf-eanno.
          b. of00-444_5b.tar.gz  - Ground Effects: ArcView point, line, and 
                      polygon Shape files bundled as one compressed tar file  
                      (0.03 MB, uncompresses to 0.2 MB). When opened, the tar 
                      file yields:
                      - point files: sf-epts.dbf, sf-epts.shp, sf-epts.shx (the 
                        points of sf-effects)
                      - line files: sf-elns.dbf, sf-elns.shp, and sf-elns.shx 
                        (the lines of sf-effects)
                      - polygon files: sf-hpys.dbf, sf-hpys.shp, and sf-hpys.shx
                        (the polygons of sf-efhspys)
                      - polygon files: sf-lpys.dbf, sf-lpys.shp, and sf-lpys.shx
                        (the polygons of sf-eflppys)

    6. Quadrangle Index Database: The data files representing the lines and 
       polygons of the 7.5-minute quadrangle and status-of-mapping index.
          a. of00-444_6a.e00.gz  - Compressed ARC export coverage (0.2 MB). 
                      Import.aml will name this sf-qdgrid
          b. of00-444_6b.tar.gz  - ArcView line and polygon Shape files bundled 
                      as one compressed tar file (0.2 MB, uncompresses  to 0.9  
                      MB). When opened, the tar file yields:
                      - line files: sf-ilns.dbf, sf-ilns.shp, and sf-ilns.shx
                      - polygon files: sf-ipys.dbf, sf-ipys.shp, and sf-ipys.shx

    7. Plot File of Quaternary Deposits Map: image size 33 x 36 inches.
          a. of00-444_7a.ps.gz  PostScript file, 5.9 MB, uncompresses to 27 MB
          b. of00-444_7b.pdf  PDF file, 5.6 MB

    8. Plot File of Liquefaction Susceptibility Map: image size 33 x 36 inches. 
          a. of00-444_8a.ps.gz  PostScript file, 6.2 MB, uncompresses to 30 MB
          b. of00-444_8b.pdf  PDF file, 5.9 MB


                                  Presentation

The database files are provided individually (including Shape files packaged in 
tar files by equivalent ARC coverages) and some of the files are also packaged 
together in larger tape archive files (.tar). Most of the larger files have been
compressed with gzip (.gz).

    Separate Text Files: The revision list (of00-444_2a.txt) and the three 
                      formats of the open-file text (of00-444_1) and the 
                      Description of Mapping (of00-444_3) are provided 
                      separately, together with an abbreviated version of the 
                      ASCII text version of part 2 as a README. These text files
                      in all three formats are also bundled in the database 
                      package.
    Separate Database Files: The Quaternary deposits and liquefaction 
                      susceptibility database (of00-444_4), the ground effects 
                      database (of00-444_5) and the quadrangle-index database 
                      (of00-444_6) are provided separately in both ARC export 
                      (.e00) and ArcView shape (.tar) formats, as well as being 
                      bundled in the database package.
    Separate Plot Files: The plot files for the Quaternary deposits map and 
                      liquefaction susceptibility map are provided separately in
                      both PostScript and PDF format, as well as being bundled 
                      together in the plotfile package.
    Database Package: The Quaternary deposits and liquefaction susceptibility 
                      layers (of00-444_4), the ground effects layers 
                      (of00-444_5), and the quadrangle index (of00-444_6) are 
                      packaged together in a single gzip-compressed tar file in 
                      both ARC (a) and ArcView shape (b) format. This package 
                      also includes text file of00-444_2a.txt and text files 
                      of00-444_1 and of00-444_3 in all three formats.
                          of00-444_9a.tar.gz   13 MB, uncompresses to 58 MB
                          of00-444_9b.tar.gz   23 MB, uncompresses to 77 MB
    Plotfile Package: Plotfiles of the Quaternary deposits map and the 
                      liquefaction susceptibility map are packaged together in a
                      single gzip-compressed tar file in both PostScript (a) and
                      PDF (b) format.
                          of00-444_10a.tar.gz   12 MB, uncompresses to 57 MB
                          of00-444_10b.tar   12 MB


                         OBTAINING THE DIGITAL FILES

The database and image files can be downloaded from the Western Region Geologic 
Information Web Server or by anonymous ftp over the Internet.

1.  Anonymous ftp over the Internet

The files for this report are stored on the Western Region publication server of
the U.S. Geological Survey.  The Internet address of this server is:

                              geopubs.wr.usgs.gov

Connect to this address directly using ftp or through a browser, log in with the
user name `anonymous', and enter your e-mail address as the password.  This will
give you access to all the publications available from the server. The files for
this report are stored in the subdirectory:

                              pub/open-file/of00-444

2.  From the Western Region Geologic Publications Web Server

The U.S. Geological Survey supports a set of graphical pages on the World Wide 
Web from which digital publications such as this one can be obtained. The Web 
server for digital publications from the Western Region is:

                              http://geopubs.wr.usgs.gov

This report can be reached by number (of00-444) through either the California or
Open-File Reports 2000 options.


                             PROCESSING THE FILES

The database files require initial processing before they are usable, both to 
open bundled and/or compressed files and to import ARC export files.


                         Opening Tar and Gzip Files

Some of the files are assembled as tape archive files (tar files), and the 
larger files containing the databases and images have been compressed with gzip.
Thus, gzip is required to uncompress the files, and a tar utility is required to
open the tar files. Once extracted from the compressed tar files, the ARC export
files can be imported into ARC/INFO using the utility import.aml that is 
included in the database package, or directly using the ARC import command.

The necessary utilities for uncompressing and extracting from tar format are 
available on-line: 

       gzip - This utility is available free of charge over the 
              Internet from the gzip Home Page:

                  http://w3.teaser.fr/jlgailly/gzip

              or via links from the USGS Public Domain Software page: 

                  http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/public.html

       tar -  This utility is included in most UNIX systems. Tar utilities for 
              PC and Macintosh can be obtained free of charge via the Internet 
              from Internet Literacy's Common Internet File Formats Web Page:  

                  http://www.matisse.net/files/formats.html

       Winzip - This commercial package runs on PCs and can deal with both gzip 
              and tar files. An evaluation copy of WinZip can be downloaded 
              from:

                  http://www.winzip.com/winzip/:  


                     Importing the ARC Export Files

The ARC export files (.e00) can be converted to ARC/INFO vector databases 
(coverages) and associated INFO files by running the import.aml that is included
in the database package. This will import the export files, assign standard 
names (see below), build polygon topology where appropriate (and if desired), 
and delete the export files once used (if desired). The 'build' and 'delete' 
options are enabled by answering YES to questions posed by import.aml. Running 
the aml again permits enabling those options previously rejected, but will not 
interfere with the results of earlier runs. The import routine checks for the 
presence of needed export files, for previously imported files, and for the need
to build if that option is enabled. Run import.aml from the ARC prompt in the 
directory containing the export files:

	ARC: &run import.aml    - run import.aml, answer YES/NO to the 
                                  questions posed in the dialog area to choose 
                                  options to import the export files, to keep or
                                  delete the export files, and to build the 
                                  imported polygon coverages. 

Note that the ARC coverages will be given standard names:

		of00-444_4a.e00       will be named	sf-quat
		of00-444_4b.e00				sf-qanno
		of00-444_5a1.e00			sf-effects
		of00-444_5a2.e00			sf-efhspys
		of00-444_5a3.e00			sf-eflppys
		of00-444_5a4.e00			sf-eanno
		of00-444_6a.e00				sf-qdgrid


                                   REVISIONS

Changes to any part of this report (parts are the numbered items described above
in 'Report Contents' and listed in the revision list of00-444_1a.txt) may be 
made in the future if needed. This could involve, for example, fixing files that
don't work properly, revising geologic details, adding new file formats, or 
adding other components to the report.

The report begins at version 1.0. Any revisions will be specified in the 
revision list and will result in the recording of a new version number for the 
report. Small changes will be indicated by decimal increments and larger changes
by integer increments in the version number. Revisions will be announced and 
maintained on the Web page for this report on the Western Region Geologic 
Publications Web Server. Consult the revision list there to determine if a 
revision is significant for your purposes.


                               MAP COMPILATION

The Quaternary deposits database was compiled digitally in vector form in 
ARC/INFO as individual 7.5-minute (126) and 0.5x1.0-degree (2) quadrangles at 
scales of 1:24,000 and 1:100,000, respectively. The 1:100,000 materials were 
modified from previously released spatial databases for the San Francisco and 
Napa 0.5x1.0-degree quadrangles (Knudsen and others, 1997, and Sowers and 
others, 1998, respectively), and the 1:24,000 materials were variously modified 
from previous work or newly digitized, depending on the degree of remapping 
involved (see part 3, Description of Mapping). These many individual pieces were
converted to UTM projection and assembled into a single regional layer. 
Remaining quadrangle boundary problems were resolved where possible, although 
some remain where the status of mapping differs across the boundary. The 
resulting spatial database retains the resolution of the input parts, some at 
1:24,000, some at 1:100,000. Much of the fine detail in the spatial database is 
too small for legible portrayal at the regional scale of the colored maps 
(1:275,000).

The ground-effects database was compiled digitally in vector form from 1:100,000
and 1:24,000 materials, including relocation at 1:24,000 of 1:250,000-scale map 
features based on text descriptions of historic effects (see Appendix C of part 
3, Description of Mapping). The Loma Prieta dataset was digitized directly in 
ARC/INFO, whereas the historic dataset was digitized in MapInfo and subsequently
converted to ARC/INFO. Points and lines for the historic and Loma Prieta 
datasets were combined into a single vector layer, but the polygons could not be
(some polygons overlap), and these remain separate.   

The vector lines in the quadrangle database were generated automatically with 
high precision in ARC/INFO as a latitude/longitude grid, densified to a vertex 
spacing of 0.005 degrees along all the lines, and reprojected to UTM .


                              SPATIAL RESOLUTION

The digital database should not be used in ways that violate the spatial 
resolution of the data.  Although the digital form of the data removes the 
physical constraint imposed by the scale of a paper map, the detail and accuracy
inherent in map scale are also present in the digital data. Use of the database 
at scales larger than 1:100,000 (or where appropriate, 1:24,000) may not yield 
greater real detail, although it may reveal fine-scale irregularities below the 
intended resolution of the database.  Similarly, where this database is used in 
combination with other data of higher resolution, the resolution of the combined
output will be limited by the lower resolution of this data.

The fact that the Quaternary deposits and ground effects datasets were assembled
from maps of different scale, some at 1:24,00 and some at 1:100,000, means that 
information of resolution greater than 1:100,000 cannot be ensured in any 
particular part of the database. The resolution of the Quaternary deposits 
database by 1:24,000 quadrangle is described in part 3 and shown on Figure 3 of 
part 3 and on the index map of map sheet 1, and is encoded in the quadrangle 
index database in the COMPIL field and directly in the SCALE field. The quality 
of the original location of contacts is distinguished by line type. The ground 
effects locations have varying original quality, as described in the database, 
and were digitized from the published 1:100,000 and 1:24,000 (San Francisco) 
maps for the Loma Prieta earthquake and from 1:24,000 relocations of earlier 
historic localities. The quadrangle boundaries in the quadrangle index are 
accurate at 1:24,000.


                    DESCRIPTION OF THE SPATIAL DATABASE

The spatial database consists of five data layers (Quaternary deposits and 
liquefaction susceptibility, quadrangle index, three ground effects layers) as 
well as two text annotation layers, all in vector form. The database structure 
for the Quaternary deposits layer follows the ALACARTE data model, such that the
primary line attribute is LTYPE and the primary polygon attribute is PTYPE. 
Appropriate definition tables are included (listed in Table 3), but the database
departs from the data model described by Gautier (1999) for single geologic maps
by including more than one topical attribute in the polygon attribute table (see
table 6). The ground effects and quadrangle index databases also contain 
multiple topical attributes in their feature attribute tables. Both the 
Quaternary deposits and ground effects databases contain label-and-leader text 
annotation layers for use in graphic display at a scale of 1:275,000 (except for
ground effects in San Francisco, which are designed for display at 1:100,000).

The ARC layers (coverages) are stored in UTM projection (table 1), whereas the 
Shape files are in decimal degrees of longitude and latitude, prepared by 
projecting and converting the primary UTM coverages. 


	Table 1.  Map Projection

		Projection	UTM          (Universal Transverse Mercator)
		Units 		METERS
		Zone 		10
		Datum		NAD27
		Spheroid	CLARKE1866


The contents of the several database layers are described in terms of the 
points, lines, polygons, and text that compose them. Descriptions of the 
database fields (items) use the terms of table 2.


	Table 2.  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


                         Quaternary Deposits Layer 

The Quaternary deposits layer contains attributed lines and polygons and 
requires polygon topology for effective use. The lines and polygons are 
described here through their feature attribute tables and associated definition 
tables (table 3).


	Table 3.  Definition Tables Included as INFO Files in the ARC Coverage 
                  SF-QUAT

		Table Name  	Function
		SF-QUAT.LN	defines line types (LTYPE)
		SF-QUAT.UN	lists names of map units by PTYPE (polygon 
				  label)
		SF-QUAT.QDEF	defines polygon LIQ values
		SF-QUAT.LIQ	lists standard LIQ rating by PTYPE (map unit)


The attribute table for lines (SF-QUAT.AAT, table 4) contains the topical 
attribute field LTYPE, the eight different values of which are described in 
table 4 and in digital form as part of the sf-quat coverage in the INFO 
definition table SF-QUAT.LN.


    Table 4.  Structure of the Quaternary-Deposits Arc Attribute Table 
              (SF-QUAT.AAT)

  	ITEM NAME	WIDTH	OUTPUT 	TYPE	N.DEC
	FNODE#		4	5	B	-	starting node of arc 
							(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
	SF-QUAT#	4  	5     	B      	-	unique internal control 
							number
	SF-QUAT-ID 	4  	5     	B      	-	unique identification 
							number
	LTYPE  		35	35	C	-	line type


	Table 5.  Line Types Recorded in the Quaternary-Deposits LTYPE Field

	This table lists the contents of the LTYPE definition table SF-QUAT.LN.
	
		LTYPE 		LDEF

 	contact, well located		depositional contact, location 
					  uncertainty less than about  100 m
	contact, approx. located	depositional contact, location 
					  uncertainty greater than about  100 m
       	contact, concealed		depositional contact concealed beneath 
					  water, fill, or levee
    	county line			boundary of nine-county region, from 
					  1:24,000 USGS DLGs and published paper
					  topographic maps
    	map boundary			exterior boundary of 1:24,000 
					  quadrangles composing the map area
  	scratch boundary		boundary without geologic attribute, 
					  here connecting mismatch of contacts 
					  or units at 7.5-minute quadrangle 
					  boundary
  	water boundary			boundary of open water from 1:24,000 
					  USGS DLGs and published paper 
					  topographic maps
  	water boundary, 1800s		landward margin of tidal marsh bordering
					  San Francisco Bay in the late 19th 
					  century, mainly from Nichols and 
					  Wright, 1971


The Quaternary-deposits polygon attribute table (SF-QUAT.PAT, table 6) contains 
the topical field PTYPE, values of which are map-label representations of the 
Quaternary map units (such as Qt). These labels and their equivalent unit names 
are listed in table 8 and in the INFO definition table SF-QUAT.UN, and are 
described in Appendix A of part 3. The codes for liquefaction susceptibility in 
the LIQ field are defined in table 7 and in the INFO definition table 
SF-QUAT.QDEF. Most susceptibility ratings are based on map unit (LIQ-SOURCE = 
0), although some are assigned custom ratings (LIQ-SOURCE = 1) based on such 
local information as depth to ground water or historical occurrence of 
liquefaction. The standard correlations between map unit and susceptibility are 
listed in Table 8, in the INFO definition table SF-QUAT.LIQ, and in table 4 of 
Part 3, Description of Mapping.


      Table 6.  Structure of the Quaternary-Deposits Polygon Attribute Table 
	(SJ-GEOL.PAT)

       	ITEM NAME         WIDTH    OUTPUT    TYPE     N.DEC	

	FNODE# 		4	5     	B	-	starting node of arc 
							  (from node)
	AREA	 	 4	12     	F      	3	area of polygon in 
							  square meters
	PERIMETER  	4	12     	F      	3	length of perimeter in 
							  meters
	SF-QUAT#	4 	5     	B      	-	unique internal control 
							  number
	SF-QUAT-ID	4	5     	B      	-	unique identification 
							  number
	PTYPE 		35	35	C	-	Quaternary unit label
	LIQ  		8	8     	C      	-	liquefaction 
							  susceptibility
	LIQ-SOURCE	1 	1	I      	-	1 where custom LIQ value
							  assigned, otherwise 0


       Table 7.  Meanings of liquefaction susceptibility codes in the LIQ field
                 (SF-QUAT.PAT)
	     This table lists the contents of the LIQ definition table 
             SF-QUAT.QDEF.

	    LIQ CODE (LIQ)    DEFINITION (QDEF)
		VH       	VERY HIGH
		H		HIGH
		M		MODERATE
		L   		LOW
		VL           	VERY LOW
		W       	WATER
		NM       	AREA NOT MAPPED


      Table 8.  Unit PTYPEs, Liquefaction Susceptibility Ratings, and Unit Names

	  This table lists in stratigraphic order the combined contents of the 
          PTYPE definition table (SF-QUAT.UN) and the PTYPE/LIQ correlation 
          table SF-QUAT.LIQ.

	    	PTYPE    	  LIQ    	        NAME

		          MODERN

		af	L	Artificial fill
		afbm	VH	Artificial fill over San Francisco Bay Mud
		alf	H	Artificial levee fill
		ads	VH	Dredge spoils
		gq	H	gravel quarry	
		ac	L	Artificial stream channel
		Qhc	VH	Modern stream channel deposits

		          LATEST HOLOCENE

		Qhfy	VH	Latest Holocene alluvial fan deposits
 		Qhly	VH	Latest Holocene alluvial fan levee deposits
		Qhty	VH	Latest Holocene stream terrace deposits
 		Qhty1	VH	Younger latest Holocene stream terrace deposits
 		Qhty2	VH	Older latest Holocene stream terrace deposits
		Qhay	VH	Latest Holocene alluvial deposits, 
				  undifferentiated
		Qhfp	VH	Late Holocene alluvial floodplain deposits, 
				  undifferentiated
		Qhfb	H	Late Holocene flood basin deposits

		          HOLOCENE

		Qhbs	VH	Holocene beach sand
		Qhds	H	Holocene dune sand
		Qhbm	H	Holocene San Francisco Bay Mud
		Qhdm	H	Holocene San Joaquin/Sacramento Delta mud and 
				  peat
		Qhb	H	Holocene basin deposits
		Qhfe	H	Holocene alluvial fan-estuarine complex deposits
		Qhff	H	Holocene alluvial fan deposits, fine facies	
  		Qhf	M	Holocene alluvial fan deposits
		Qhf1	M	Younger Holocene alluvial fan deposits
 		Qhf2	M	Older Holocene alluvial fan deposits
 		Qhl	M	Holocene alluvial fan levee deposits
		Qhl1	M	Younger Holocene alluvial fan levee deposits
		Qhl2	M	Older Holocene alluvial fan levee deposits
		Qht	H	Holocene stream terrace deposits
 		Qht1	H	Younger Holocene stream terrace deposits
 		Qht2	H	Older Holocene stream terrace deposits
		Qha	H	Holocene alluvium, undifferentiated

		          LATEST PLEISTOCENE TO HOLOCENE

		Qds	M	Latest Pleistocene to Holocene dune sand
 		Qb	L	Latest Pleistocene to Holocene basin deposits
 		Qf	L	Latest Pleistocene to Holocene alluvial fan 
				  deposits
 		Ql	L	Latest Pleistocene to Holocene alluvial fan 
				  levee deposits
 		Qt	M	Latest Pleistocene to Holocene stream terrace 
				  deposits
		Qa	M	Latest Pleistocene to Holocene alluvium, 
				  undifferentiated

		          LATEST PLEISTOCENE

		Qpb	L	Latest Pleistocene basin deposits
 		Qpf	L	Latest Pleistocene alluvial fan deposits
 		Qpt	L	Latest Pleistocene stream terrace deposits
		Qpa	L	Latest Pleistocene alluvium, undifferentiated

		          EARLY TO LATE PLEISTOCENE

		Qmt	L	Pleistocene marine terrace deposits
		Qmt1	L	Youngest (of 4) Pleistocene marine terrace 
				  deposits
		Qmt2 	L	Second youngest (of 4) Pleistocene marine 
				  terrace deposits
		Qmt3 	L	Second oldest (of 4) Pleistocene marine terrace 
				  deposits
		Qmt4 	L	Oldest (of 4) Pleistocene marine terrace 
				  deposits
 		Qop	VL	Early to late Pleistocene pediment deposits
		Qof	VL	Early to late Pleistocene alluvial fan deposits
		Qof1	VL	Younger early to late Pleistocene alluvial fan 
				  deposits
 		Qof2	VL	Older early to late Pleistocene alluvial fan 
				  deposits
		Qot	VL	Early to late Pleistocene stream terrace 
				  deposits
		Qoa	VL	Early to late Pleistocene alluvial deposits, 
				  undifferentiated
 		Qoa1	VL	Younger early to late Pleistocene alluvial 
				  deposits, undifferentiated
 		Qoa2	VL	Older early to late Pleistocene alluvial 
				  deposits, undifferentiated

		          PRE-PLEISTOCENE

		br	VL	bedrock


The text annotation layer sf-qanno contains the unit labels and leaders used to 
label the Quaternary units on map sheet 1, Quaternary Deposits. All lines in the
layer are leaders, with LTYPE = 'leader'. All labels are level 1 annotation, 582
m high (map units), with $symbol = 20. The lines and labels are scaled and 
positioned for graphic presentation at a scale of 1:275,000. 


                            Ground Effects Layers

The ground effects are assembled in three layers: a single layer of points and 
lines (sf-effects) for all the effects that can be represented by points or 
lines, including localities representing uncertain distribution of effects, and 
two separate polygon layers (sf-efhspys, sf-eflppys) for areas that can be 
delimited by boundaries, one each for the datasets for historic and for Loma 
Prieta effects. These must remain separate because some of the polygons overlap.
The polygon layers require polygon topology for effective use. Information about
the areas is attached to the polygons (label points), not to their bounding 
lines. Original station numbers from the two source documents (Youd and Hoose, 
1978; Tinsley and others, 1998) are recorded in the database and are shown on 
the map to facilitate recovery of complete descriptions for each station. The 
locations, station numbers, and summary of effects are shown on map sheet 2, 
Liquefaction Susceptibility. 

The historic localities of Youd and Hoose (1978) have been relocated at 1:24,000
based on the descriptions of the localities (see Appendix C in part 3, 
Description of Mapping), with the result that single Youd and Hoose localities 
can be represented by multiple localities in the database, all with the same 
original station number.

Accuracy ratings are reported as presented by Youd and Hoose (Table 9), and 
where different table entries for the same locality were given different 
ratings, these are aggregated for the locality (for example, 'B,C') and are 
assigned to each of the relocated occurrences for that locality.  Accuracy 
ratings for the relocated occurrences (Table 10) are separately assigned. The 
resulting accuracy ratings for each map element in the ACC database field thus 
have two parts, a Youd-and-Hoose rating followed by a relocation rating, the two
separated by a colon (for example 'A:P').


	Table 9. Location-Accuracy Categories of Youd and Hoose (1978).

	   A	"a site that can be accurately relocated"
	   B	"a site that can be relocated to within a few kilometers and 
		 probably could be located more 
			 accurately with further investigation"
	   C	"a site where the information is insufficient to allow precise 
		 location"


	Table 10. Relative Accuracy of Relocated Historic Effects

		P	located to within 100 meters
		Q 	located to within 500 meters
		R 	located to within 1 kilometer
		S	location is indefinite or approximate


Database fields (items) for the three ground-effects data layers are largely the
same (Table 11). Exceptions involve the standard fields related to the specific 
coverage name and the kind of feature, and fields for polygon boundaries (lines)
in the polygon layers sf-efhspys and sf-eflppys, which carry no topical 
attributes except SF. The meaning or content of the topical fields are described
in Table 12. Note that the -ID number has been set to a unique value for each 
record within all three layers combined, and thus serves as a unique identifier 
for each map element in the database. The database fields LS-H through ABS 
separately record the presence of the various kinds of ground effects at each 
station. A value of 1 indicates presence (including the positive indication of 
the absence of effects - ABS), whereas 0 means that the effect was not indicated
for the station.


	Table 11.  Ground-Effects Database Fields. 

	 FIELD (ITEM)  WIDTH  OUTPUT   TYPE   N.DEC	FIELD VALUE

     For points and polygons (.PAT)
	AREA 		4	12	F	3	area of polygon, 0 for
							  points
    	PERIMETER	4	12	F	3	perimeter length in m,
							  0 for points

     For lines (.AAT)
	FNODE#		4	5	B	-	from node ID number 
	TNODE# 		4	5	B	-	to node ID number
	LPOLY#		4	5	B	-	left polygon ID number
	RPOLY#		4	5	B	-	right polygon ID 
							  number
	LENGTH 	  	4	5	B	-	length of line in m

     For points, polygons, and lines in sf-effects
    	[COVNAME]# 	  4	  5	B	-	control number 
							  assigned by ARC/INFO
   	[COVNAME]-ID	  4	  5	B	-	unique integer that 
						 	  identifies map element
							  in the database (user 
							  assigned)
   	STA 	  	5	  5	C	-	field station number 
							  from source
   	EQK		10	10	C	-	date of earthquake(s)
   	SRC		30	30	C	-	source of information
   	KIND		12	12	C	-	kind of locality 
							  (point, line, area)
   	ACC	 	  5	  5	C	-	accuracy of location
   	EXT 		10	10	C	-	extent of occurrence
   	COMM		50	50	C	-	comment by digital 
							  compiler
  	FIELD 		50	50	C	-	field description
  	LS-H		1	1	I	-	landslide, hillside
  	LS-S 		1	1	I	-	landslide, stream bank
  	LATSP		1	1	I	-	lateral spread
  	SETL 		1	1	I 	-	ground settlement
  	CRK-ST		1	1	I	-	cracks in street
  	CRK-GND	  	1	1	I	-	cracks in ground 
							  without other effect
  	PIPE		1	1	I	-	pipeline break
  	BOIL		1	1	I	-	sand boil
  	WELL		1	1	I	-	disturbed well
  	MISC		1	1	I	-	miscellaneous effect
  	ABS		1	1	I	-	absence of ground 
							  failure
  	EFFECTS		35	35	C	-	list of effects 
							  present (item names)

              For all feature types
	SF		1	1	I	-	1 for inset, otherwise 0



       Table 12.  Description of Topical Database Fields in Ground Effects 
                  Database. 

    STA - The original location or field station number assigned by Youd and 
        Hoose (1978) or Tinsley and others (1998) is recorded in the STA field. 
        Note that for the historic data, multiple locations may have the same 
        station number and that overlapping sequences of station numbers were 
        used for the historic and the Loma Prieta localities.

    EQK - The earthquake(s) by year of occurrence (1838-1989) for which effects 
        are represented at each locality is reported in  the EQK field. 

    SRC - The documentary source, either Youd and Hoose (1978), or Tinsley and 
        others (1998), is recorded in the SRC field. 

    KIND - The shape or kind of occurrence is recorded in the KIND field as 
        point, symbol, line, or area. A value of 'symbol' marks the 10 Loma 
        Prieta localities for which only an effects symbol is shown (without an 
        associated dot marking the mapped location). This less specific location
        is also indicated by an accuracy rating of Q, rather than the more 
        accurate P.  

    ACC - The map accuracy of the map elements arises both from the original 
        mapping or map placement of the effect and from digital representation 
        of that map location. Accuracy of the historic data is recorded in the 
        ACC field according to both the Youd and Hoose categorization (table 1) 
        and the relocation categories of table 2. These two different accuracy 
        categorizations are reported in that order, separated by a colon. Thus, 
        typical ACC values might be 'A:P' or 'B,C:Q'. Quality of location 
        accuracy on the source maps for the Loma Prieta data is also described 
        according to the relocation categories of table 2. 

    EXT - The extent field is used to record dimensions for those few historic 
        localities where the horizontal extent of the effect could be estimated.
        Values are in meters.

    COMM - Various limiting or clarifying comments about the locality or its map
        location are recorded in the COMM field.

    FIELD - The field occurrence of the effects is summarized for the Loma
        Prieta data in the FIELD field.

    EFFECTS - the aggregate or combination of effects at each station is 
        recorded in the EFFECTS field, with presence of each indicated by the 
        field name for that effect. Typical values might thus be 'BOIL' for 
        stations exhibiting just sand boils, or 'LATSP SETL BOIL' for stations 
        exhibiting a combination of lateral spread, settlement, and sand boils.


The text annotation layer sf-eanno contains the station numbers, leaders, and 
inset box boundary used to label the ground-effects localities on map sheet 2, 
Liquefaction Susceptibility. All lines are leaders, with LTYPE = 'leader', 
except the boundary of the inset box (LTYPE = 'box') around San Francisco. 
Station numbers are divided into four groups that distinguish historic from Loma
Prieta stations and those numbers displayed at a scale of 1:275,000 from those 
displayed at 1:100,000.  

Loma Prieta station labels have $symbol = 21 and are level 1 (most stations) or 
level 3 (inset map), whereas historic labels have $symbol = 22 and are level 2 
(most stations) or level 4 (inset map). Most labels are 698.5 m (map units) high
for display at a scale of 1:275,000, whereas those within the inset box are 254 
m high. 

Points, lines, and polygons in the data layers are coded for display at a scale 
of 1:275,000 or on the inset map at 1:100,000. Features within the inset box 
have an SF value of 1, whereas all others have a value of 0.


                          Quadrangle Index Layer 

The quadrangle index layer delineates and names the 7.5-minute quadrangles in 
the region. It contains attributed lines and polygons and requires polygon 
topology for effective use. The line attribute table (SF-QDGRID.AAT, table 13) 
contains the topical field LTYPE, the four different values of which are 
described in table 14, and the field TICS, the three values of which are 
described in table 15. The LTYPE field permits separate selection of the 
boundaries of the 7.5-minute, 15-minute, and 0.5x1.0-degree quadrangles. The 
TICS field permits selection of short (500 m) line segments representing the 
corner tics of the 7.5-minute and 15-minute quadrangles. Both are character 
fields. Three sets of text annotation are also included. The names of the 7.5 
minute quadrangles are represented by text running diagonally across each 
quadrangle (level 2) and by horizontal text in the upper left corner of each 
quadrangle (level 3), and compilation codes (COMPIL values) are represented near
the south boundary of each quadrangle (level 1). The meanings of these codes are
described in table 3 of part 3, Description of Mapping.


       Table 13.  Structure of the Quadrangle-Index Arc Attribute Table 
                   (SF-QDGRID.AAT)

  	ITEM NAME         WIDTH   OUTPUT    TYPE      N.DEC
	FNODE#		4	5	B	-	starting node of arc 
							  (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
	SF-QDGRID#	4	5     	B      	-	unique internal control 
							  number
	SF-QDGRID-ID 	4	5     	B      	-	unique identification 
							  number
	LTYPE 		35	35	C	-	type of quadrangle 
							  boundary 	
	TICS  		  4	  4	C	-	type of quadrangle 
							  boundary


       Table 14.  Quadrangle-Boundary Line Types Recorded in the 
                  Quadrangle-Index LTYPE field (SF-QDGRID.AAT)

		LTYPE
		100		boundary of  0.5x1.0-degree quadrangle
		 15		boundary of 15-minute quadrangle (and not a 
				  0.5x1.0-degree boundary)
		7.5		boundary of 7.5-minute quadrangle (and not a 
				  15-minute boundary)
		santa cruz 	boundary of the non-standard Santa Cruz 1:24,000
				  quadrangle


       Table 15. Quadrangle Corner-Tic Line Types Recorded in the 
                 Quadrangle-Index TICS field (SF-QDGRID.AAT)

	 	TICS
			no value for lines that are not tics
		15	corner of 15-minute quadrangle
		7.5	corner of 7.5-minute quadrangle (and not a 15-minute 
			  corner)


The quadrangle-index polygon attribute table (QDGRID.PAT) contains four topical 
fields that are described in table 16. The NAME and SHEET fields identify the 
7.5-minute quadrangle and the 0.5x1.0-degree quadrangle that contains it. The 
COMPIL field contains the map compilation code described in part 3, Description 
of Mapping, and the PERCENT field contains the percent completion of Quaternary 
mapping for each 7.5-minute quadrangle according to the criteria described in 
part 3 (values range from 50 to 100, in 5 percent increments). The 7.5-minute 
quadrangles in the index map on map sheet 1 (Quaternary Deposits) are colored 
according the PERCENT values, and the COMPIL codes are posted in the lower left 
corner of each quadrangle. COMPIL values containing 6, 10, or 11 represent 
largely 1:100,000-scale material, whereas the others represent 1:24,000-scale 
materials.


	Table 16.  Structure of the Quadrangle-Index Polygon Attribute Table (SJ-GEOL.PAT)

       		ITEM NAME	WIDTH 	 OUTPUT      	TYPE   	N.DEC	

	AREA		4	12	F      	3	area of polygon in 
							  square meters
	PERIMETER	4	12     	F      	3	length of perimeter in 
							  meters
	SF- QDGRID #	4	5     	B      	-	unique internal control 
							  number
	SF- QDGRID -ID	4	5     	B      	-	unique identification 
							  number
	NAME   		35	35	C	-	name of 7.5-minute 
							  quadrangle
	SHEET       	35	35	C	-	name of 0.5x1.0-degree 
							  quadrangle
	COMPIL		7	7     	C      	-	compilation code
	PERCENT		3	3	I      	-	percent completion of 
							  mapping
	SCALE		4	4	I      	-	scale of source map (24 
							  or 100)


                               REFERENCES CITED

Atwater, B.F., 1982, Geologic maps of the Sacramento-San Joaquin Delta, 
  California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1401, 
  map scale 1:24,000.

Fitzgibbon, T.T., 1991, ALACARTE installation and system manual (version 1.0): 
  U.S. Geological Survey, Open-File Report 91-587B.

Fitzgibbon, T.T., and Wentworth, C.M., 1991, ALACARTE user interface - AML code 
  and demonstration maps (version 1.0): U.S. Geological Survey, Open-File Report
  91-587A.

Gautier, D.L., 1999, Data model for single geologic maps: an application of the 
  national geologic map data model, in, Soller, D.R., ed., Digital mapping 
  techniques '99 -- workshop proceedings: U.S. Geological Survey Open-File 
  Report 99-386.

Helley, E.J., and Graymer, R.W., 1997a, Quaternary geology of Alameda County, 
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  and San Joaquin Counties, California: A digital database: U.S. Geological 
  Survey Open-File Report 97-97, map scale 1:24,000.

Helley, E.J., and Graymer, R.W., 1997b, Quaternary geology of Alameda County and
  parts of Contra Costa, Santa Clara, San Mateo, San Francisco, Stanislaus, and 
  San Joaquin Counties, California: a digital database: U.S. Geological Survey 
  Open-File Report 97-97, map scale 1:24,000.

Helley, E.J., Graymer, R.W., Phelps, G.A., Showalter, P.K, and Wentworth, C.M., 
  1994: Preliminary Quaternary geologic maps of Santa Clara Valley, Santa Clara,
  Alameda, And San Mateo Counties, California: a digital database: U.S. 
  Geological Survey Open-File Report 94-231, map scale 1:24,000.

Helley, E.J., Lajoie, K.R., Spangle, W.E., and Blair, M.L., 1979, Flatland 
  deposits of the San Francisco Bay Region, California - Their geology and 
  engineering properties, and their importance to comprehensive planning:  U.S. 
  Geological Survey Professional Paper 943, 88 p., map scale 1:125,000.

Knudsen, K.L, Noller, J.S., Sowers, J.M., and Lettis, W.R., 1997, Quaternary 
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  quadrangle: A digital database: U.S. Geological Survey Open-File Report 
  97-715, map scale 1:100,000.

Knudsen, K.L., Sowers, J.M., Witter, R.C., Helley, E.J., Wentworth, C.M., 
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  liquefaction susceptibility, nine-county San Francisco Bay area, California: 
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Nichols, D.R., and Wright, N.A., 1971, Preliminary map of historical margins of 
  marshland, San Francisco Bay, California: U.S. Geological Survey Open-File 
  Report, Basic Data Contribution 9, scale 1:125,000. 

Sowers, J.M, Noller, J.S., and Lettis, W.R., 1998, Quaternary geology And 
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  Database: U.S. Geological Survey Open-File Report 98-460, map scale 1:100,000.

Tinsley, J.C. III, Egan, J.A., Kayen, R.E., Bennett, M.J., Kropp, Alan, and 
  Holzer, T.L., 1998, Appendix: maps and descriptions of liquefaction and 
  associated effects, in Holzer, T.L., ed, The Loma Prieta, California, 
  Earthquake of October 17, 1989---liquefaction: U.S. Geological Survey 
  Professional Paper 1551-B, p. B287-B314, map scales 1:100,000 and 1:24,000.

Wentworth, C.M., and Fitzgibbon, T.T., 1991, ALACARTE user manual (version 1.0):
  U.S. Geological Survey, Open-File Report 91-587B.

Working Group on California Earthquake Probabilities, 1999, Earthquake 
  probabilities in the San Francisco Bay Region: 2000 to 2030 - A summary of 
  findings: U.S. Geological Survey Open File Report 99-517, Online Version 1.0.

Youd, T.L., and Hoose, S.N., 1978, Historic ground failures in northern 
  California triggered by earthquakes: U.S. Geological Survey  Professional 
  Paper 993, map scales 1:250,000 and 1:24,000.