


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



GEOLOGIC MAP OF THE HAYWARD FAULT ZONE, 
CONTRA COSTA, ALAMEDA, AND SANTA CLARA 
COUNTIES, CALIFORNIA:  A DIGITAL 
DATABASE

By

R.W. Graymer, D.L. Jones, and E.E. Brabb



Open - File Report 95-597





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 "Geologic map of the Hayward fault zone, 
Contra Costa, Alameda, and Santa Clara Counties, California:  A digital 
database," has been approved for release and publication by the Director 
of the USGS.  Although this database has been subjected to rigorous 
review and is substantially complete, the USGS reserves the right to 
revise the data pursuant to further analysis and review.  Furthermore, 
it is released on condition that neither the USGS nor the United States 
Government may be held liable for any damages resulting from its 
authorized or unauthorized use.



1995


Introduction

This digital map database, compiled from previously open-
filed U.S. Geological Survey reports (Graymer and others, 
1994, Graymer, Jones, and Brabb, 1994) and unpublished data, 
represents the general distribution of rocks and faults in 
the Hayward fault zone.  As described in this report, the 
Hayward fault zone is a zone of highly deformed rocks which 
trends north 30 degrees west from an area southeast of San 
Jose to the San Pablo Bay, and ranges in width from 2 to 10 
kilometers.  Although historic earthquake activity has been 
concentrated in the western part of the zone, the zone as a 
whole reflects oblique right-lateral and compressive 
deformation along a significant upper crustal break over the 
past 10 million years or more.  Together with the 
accompanying text file (hfgeo.txt), the database provides 
current information on the distribution and description of 
faults and rock types within the fault zone.  In addition, 
the text file discusses the development of the fault zone in 
the past 10 million years, the relationship of the Hayward 
and Calaveras fault zones, and the significance of the 
creeping strand of the Hayward fault (as most recently 
defined by Lienkaemper, 1992).  The scale of the source maps 
limits the resolution (scale) of the database to 1:50,000, 
except for Alameda County which has a resolution of 1:24,000.  
For those interested in the geology of the Hayward fault zone 
who do not use an ARC/INFO compatible Geographic Information 
System (GIS), three Postscript plot files containing images 
of much of the data in the digital database have been 
included.  The content and character of the database, as well 
as two methods of obtaining the database, are described 
below. 

Database Contents

The digital database consists of the geologic map database 
itself and the supporting data, including a fault map, base 
maps, map explanation, geologic description, and references.  
The geologic map database consists of three ARC coverages:

	hfcc_um/	Geologic map of the Hayward fault zone 
			in Contra Costra County
	hfal_um/	Geologic map of the Hayward fault zone in 
			Alameda County
	hfsc_um/	Geologic map of the Hayward fault zone in
 			Santa Clara County
	
The database directory also includes the following supporting 
directory, ARC coverages, and files:

Directory:
	info/		INFO directory containing files
 			supporting the databases

ARC Coverages:
	hf_um-flt/	Map of faults in the Hayward fault zone
			with additional database items containing
			fault name (if any) and fault subzone (see 
			hfgeo.txt for explanation of subzones).

	hf_dr/		Drainage base map.
	hf_cu/		Cultural base map.
	hf_topo/	Topographic contours base map.


Files:
	hfgeo.txt	A text only computer file containing detailed
			unit descriptions and geological information, 
			plus sources of data and references cited.

	hfdb.txt	This file.

	hfkey.un	Together, these key files produce a
	hfkey.ln	plottable or displayable map explaination
			and key.

	hfnplt.ps	A Postscript  plottable file containing an
			image of the geologic map of the northern half 
			of the Hayward fault zone at a scale of 
			1:50,000 (Sheet 1).

	hfsplt.ps	A Postscript plottable file containing an 
			image of the geologic map of the southern half 
			of the Hayward fault zone at a scale of 
			1:50,000 (Sheet 2).

	hf-fplt.ps	A Postscript plottable file containing an 
			image of the map of faults within the Hayward 
			fault zone color coded to correspond to 
			subzone at a scale of 1:100,000 (Sheet 3, see 
			text file hfgeo.txt for explanation of 
			subzones).
	
	The database was compiled in ARC/INFO, a commercial 
Geographic Information System (Environmental Systems Research 
Institute, Redlands, California), and is stored in ARC 
coverage format (ARC/INFO version 7) in a UNIX tar file.  A 
UNIX computer operating system is therefore required to 
extract the database from the tar file, and ARC/INFO is 
required for its use or conversion to other format.  The 
digital compilation was done using version 7.0.2 of ARC/INFO 
with version 3.0 of the menu interface ALACARTE (Fitzgibbon 
and Wentworth, 1991, Fitzgibbon, 1991, Wentworth and 
Fitzgibbon, 1991).

Obtaining the Digital Data

An 18.6 MB compressed tar file of the database and related 
files can be obtained by anonymous ftp over Internet, or by 
sending a tape with request and return address to:

	Hayward fault zone Database
	c/o Carl M. Wentworth
	U.S. Geological Survey
	345 Middlefield Road, M/S 975
	Menlo Park, CA 94025

Do not omit any part of this address!

The compressed tar file will be returned on the tape.  The 
acceptable tape types are:
	1/4 inch, 150 MB cartridge tape
	2.3 or 5.0 GB, 8 mm Exabyte tape.


To obtain the tar file by ftp, log in to your UNIX system and 
do the following:
	cd local_directory	-go to a directory to receive 
				  the tar file
	ftp sierra.wr.usgs.gov	-make ftp connection with the 
				  USGS computer Sierra
	Name: anonymous		-use "anonymous" as your user 
				  name
	Password: your name	-use your own user name as 
				  password
	cd pub			-go down to the pub directory
	type binary		-change transfer type to binary
	get hf_g1.tar.Z		-copy the compressed tar file
 				  across Internet to your directory
	quit			-close the ftp connection

Extracting the Database from the Tar file

If you obtained the database on tape:
	put the tape in your tape drive

	cd local_directory	-go to a directory to receive the 
				  tar file
	tar xvfb /dev/rstn 20	-/dev/rstn is the tape device with
 				  n an integer, this puts the tar file 
				  in local_directory
	uncompress hf_g1.tar.Z	-makes a 51 MB uncompressed 
				  tar file hf_g1.tar
	cd local_directory2	-go to the directory that will hold 
				  the workspace hfg (if different 
				  from local_directory)
	tar xvfb {path to tar 
	file}/hf_g1.tar 20	-extract the hfg workspace from 
				  the tar file.

If you obtained the database by anonymous ftp:
	uncompress hf_g1.tar.Z	-makes a 51 MB uncompressed 
				  tar file hf_g1.tar
	cd local_directory2	-go to the directory that will hold 
				  the workspace hfg (if different 
				  from local_directory)
	tar xvfb {path to tar 
	file}/hf_g1.tar 20	-extract the hfg workspace from 
				  the tar file.

This process will create a workspace "/hfg" (a directory 
containing an INFO directory) that contains the databases and 
supporting files as described above.

Digital Compilation

The geologic map information was digitized from stable 
originals of the geologic maps at 1:24,000 scale for Alameda 
County and 1:62,500 scale for Santa Clara and Contra Costa 
County.  The author manuscripts (ink on mylar) were scanned 
using a Tektronix 4991 monochrome scanner with a resolution 
of 304.8 dots per inch.  The scanned images were vectorized 
and transformed from scanner coordinates to projection 
coordinates with  digital tics placed by hand at quadrangle 
corners.  The scanned lines were edited interactively by hand 
using ALACARTE, color boundaries were tagged as a contact or 
fault as appropriate, and scanning artifacts visible at 
1:24,000 (for Alameda County) or 1:50,000 (for Santa Clara or 
Contra Costa Counties) were removed. 

Base Maps

Base Map layers were prepared from scale-stable printing 
negatives of the U.S. Geological Survey Napa (1983 edition), 
San Francisco (1978 edition), Stockton (1989 edition), and 
San Jose (1978 edition) 1:100,000 topographic maps, which 
have a 50 meter contour interval.  Scanned and vectorized 
images were transformed from scanner coordinates to 
projection coordinates with digital tics placed by hand at 
map corners.  The images were then trimmed interactively by 
hand using ALACARTE to conform to the area of the geologic 
coverages, and the four portions were combined.  Small 
mismatches at the boundaries caused by slight differences in 
the original scans remain in the three base map coverages.  
These base map layers are digital images but no information 
other than location is attached to the lines.  The base maps 
are provided for reference only.

Faults and Landslides

This map is intended to be of general use to engineers and 
land-use planners.  However, its small scale does not provide 
sufficient detail for site developement purposes.  In 
addition, this map does not take the place of fault-rupture 
hazard zones designated by the California State Geologist 
(Hart, 1988).  Similarly, the database cannot be used to 
identify or delineate most landslides in the region, because 
only some large landslides are shown.  For a more complete 
depiction of landslide distribution, see Nilsen and others 
(1979).

Spatial Resolution

Uses of this digital geologic map should not violate the 
spatial resolution of the data.  Although the digital form of 
the data removes the constraint imposed by the scale of a 
paper map, the detail and accuracy inherent in map scale are 
also present in the digital data.  The fact that this 
database was edited at a scale of 1:24,000 (for Alameda 
County) or 1:50,000 (for Contra Costa and Santa Clara 
Counties) means that higher resolution information is not 
present in the dataset.  Plotting at scales larger than 
1:24,000 (for Alameda County) or 1:50,000 will 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 
these data.  Note that in contrast to the geologic coverages, 
the base map layers have a resolution of 1:100,000, so 
significant discrepancies with the geologic coverages are 
possible.  The base map layers are provided for reference 
only.

Postscript Plot Files

The database is in ARC coverage format, and therefore 
requires use of ARC/INFO or another compatible GIS system to 
access the information contained within it.  For those 
interested in the geology of the Hayward fault zone, but who 
don't use an ARC/INFO compatible GIS system, we have included 
three Postscript plot files.  One contains a plot of the 
northern half of the map database at 1:50,000 scale, along 
with a map explanation (Sheet 1, hfnplt.ps).  The second 
contains a plot of the southern half of the map database at 
1:50,000 scale, along with a diagram of quadrangles traversed 
by the fault zone (Sheet 2, hfsplt.ps).  The third contains a 
plot of the fault information map (explained below) at 
1:100,000 scale (Sheet 3, hf-fplt.ps).  Because this release 
is primarily a digital database, the plot files (and plots 
derived therefrom) have not been edited to conform to U.S. 
Geological Survey standards.  Small units have not been 
labeled with leaders and in some instances map features or 
annotation overlap.  Sample plots by the authors have proven 
to be quite legible and useful, however.

Fault Information Map (hf_um-flt)

This coverage contains additional information about the 
faults in the Hayward fault zone.  The subzone that the fault 
is in is recorded in the database item "DOMAIN."  The fault 
name, if any, is recorded in the database item "FNAME."  See 
below for more information about database items.  Subzones 
are fully described in the accompanying text file, hfgeo.txt.  
This coverage contains fault lines (arcs) from all three 
counties, but no contact lines (arcs) or polygon information.  
This coverage is intended to illustrate concepts discussed in 
the geologic explanation (hfgeo.txt).

Database Specifics

The map databases consist of ARC coverages and supporting 
INFO files, which are stored in a UTM (Universal Transverse 
Mercator) projection (Table 1).  Digital tics define a 7.5 
minute grid of latitude and longitude in the geologic 
coverages corresponding with quadrangle corners.  In the base 
map layers, the tics define a 7.5 minute grid, corresponding 
with quadrangle corners.

Table 1 - Map Projection
The map is stored in UTM projection

PROJECTION UTM		-Universal Transverse Mercator
UNITS METERS		-on the ground
ZONE 10			-UTM zone
PARAMETERS
END

  The content of the geologic database can be described in 
terms of the lines and the areas that compose the map.  
Descriptions of the database fields use the terms explained 
in 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

Lines - 

	The lines (arcs) are recorded as strings of vectors and 
are described in the arc attribute table (Table 3).  They 
define the boundaries of the map units, faults that do not 
bound units, the boundaries of open bodies of water, and the 
map boundaries.  These distinctions, including the geologic 
identities of the unit boundaries, are recorded in the LTYPE 
field according to the line types listed in Table 4.  In 
addition, the coverage hf_um-flt contains two extra database 
items in the arc attribute table containing additional 
information related to faults within the Hayward fault zone.

Table 3 - Content of the Arc Attribute Tables

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
<coverage>#	4	5	B		unique internal
						control number
<coverage>-ID	4	5	B		unique 	
						identification 
						number
LTYPE		35	35	C		line type (see 
						Table 4)
DOMAIN		35	35	C		structural subzone 
						(hf_um-flt only)
FNAME		35	35	C		fault name
						(hf_um-flt only)


Table 4 - Line Types Recorded in the LTYPE Field

atten. fault, certain (hf_um-flt only)
atten. fault, approx. located (hf_um-flt only)
contact, certain
contact, approx. located
contact, inferred
fault, certain
fault, approx. located
fault, concealed
fault, concealed, queried
fault, inferred
fault, inferred, queried
s.s. fault, r.l., approx. located
s.s. fault, r.l., certain
thrust fault, approx. located
thrust fault, certain
thrust fault, concealed
scratch boundary
water boundary
map boundary

The geologic linetypes are ALACARTE line types that correlate 
with the geologic line symbols in the ALACARTE line set 
GEOL61.LIN according to the ALACARTE lines lookup table 
(GEOL61.LUT).  Note that fault and s.s. fault, r.l. are 
assigned the same symbol in the lookup table.

Areas - 

	Map units (polygons) are described in the polygon 
attribute table (Table 5)  The identities of the map units 
from compilation sources are recorded in the PTYPE field by 
map label (Table 6).  Map units are described more fully in 
the accompanying text file hfgeo.txt.

Table 5 - Content of the Polygon Attribute Tables

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
<coverage>#	4	5	B		unique internal 
						control number
<coverage>-ID	4	5	B		unique
						identification
						number
PTYPE		35	35	C		unit label


Table 6 - Map Units
(See hfgeo.txt for descriptions of units)


.
JKf
JKfgm
JKfm
JKfn
JKk
Jkkc
JKkv
Jgb
Jpb
Jbp?
Jsv
Kc
Kcv
Kjm
Knc
Ko
Ko?
Kp
Kr
Ksc
Ksh
Kslt
Ku
QTi
QTi?
QTl
QTp
QTs
Qls
Qm
Qoa
Qu
Ta
Tbp
Tbr
Tcc
Tccs
Tccs?
Tes
Tgs
Tgss
Tm
Tms
Tn
To
To?
Tor
Torv
Tps
Ts
Tsh
Tsk
Tss
Tst
Tt
Ttls
Tts
Tus
Tush
Tv
fc
fg
fm
fs
sc
sp
sp?




Acknowledgments

We are grateful to Kristin R. McDougall, William V. Sliter, 
David Bukry, John A. Barron, and William P. Elder of the U.S. 
Geological Survey for the paleontologic determinations 
necessary to help establish the ages of rocks in the Hayward 
fault zone.  Scott D. Hill, Superintendent of Watershed, 
kindly provided access to lands owned by the East Bay 
Regional Park District.  Leo T. Bauer, Alameda Division 
Manager, provided access to lands owned by the San Francisco 
Water Department.  G. Doug Myron, U.S. Geological Survey, 
arranged for access to some of the private land in the study 
area.  Carl M. Wentworth, Todd T. Fitzgibbon, and Geoffrey A. 
Phelps graciously provided assistance with Alacarte and 
ARC/INFO.  James J. Lienkaemper shared some of his knowledge 
of the creeping strand of the Hayward fault, and David. H. 
Oppenheimer provided maps showing the location of epicenters.  
Larry J. Dickerson and John M. Parker, U.S. Geological Survey 
volunteers, provided extensive support in the field.  We are 
grateful to AmeriCorps for sponsoring Dickerson, Parker, and 
Brabb.

References Cited

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.
Graymer, R.W., Jones, D.L., and Brabb, 1994, Preliminary 
  geologic map emphasizing bedrock formations in Contra 
  Costa County, California:  A digital database:  U.S. 
  Geological Survey Open-File Report 94-622.
Graymer, R.W., Jones, D.L., Brabb, E.E., and Helley, E.J., 
  1994, Preliminary geologic map of the Niles 7.5-minute 
  quadrangle, Alameda County, California:  U.S. Geological 
  Survey Open-File Report 94-132, 3 sheets, 1:24,000 
  scale.
Hart, E.W., 1988, Fault-rupture hazard zones in California; 
  Alquist-Priolo Special Studies Zones Act of 1972 with 
  index to special studies zones maps:  California 
  Division of Mines and Geology Special Publication 42.
Lienkaemper, J.J., 1992, Map of recently active traces of the 
  Hayward fault, Alameda and Contra Costa Counties, 
  California:  U.S. Geological Survey Misc. Field Studies 
  Map MF-2196, 13 p., 1 sheet, 1:24,000 scale.
Nilsen, T.H., Wright, R.H., Vlasic, T.C., and Spangle, W.E., 
  1979, Relative slope stability and land-use planning in 
  the San Francisco Bay region, California:  U.S. 
  Geological Survey Professional Paper 944, 96 p.
Wentworth, C.M., and Fitzgibbon, T.T., 1991, ALACARTE user 
  manual (version 1.0):  U.S. Geological Survey, Open-File 
  Report 91-587C.

