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



QUATERNARY GEOLOGY AND LIQUEFACTION 
SUSCEPTIBILITY, NAPA, CALIFORNIA 1:100,000 
QUADRANGLE: A DIGITAL DATABASE

By

Janet M. Sowers1, Jay S. Noller1 and William R. Lettis1


Open - File Report 98-460





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 "Quaternary Geology and Liquefaction Susceptibility, Napa, California 
1:100,000 Quadrangle:  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.1998












1William Lettis & Associates, Inc., 1777 Botelho Dr., Suite 262, Walnut Creek, CA 94596
  (510) 256-607

INTRODUCTION

   This Open-File report consists of a digital geologic map database and associated digital 
plot files and text files, revised from a hard copy by Sowers and others (1995).  This 
pamphlet serves to introduce and describe the digital data.  There are no paper maps 
included in the Open-File report.  The report does include, however, PostScript plot files 
and Portable Document Format (PDF) plot files containing the images of the geologic map 
sheet and the liquefaction susceptibility sheet with explanations, as well as the 
accompanying text describing the geology of the area.  For those interested in a paper plot 
of information contained in the database or in obtaining the PostScript plot files, please see 
the section entitled "For Those Who Aren't Familiar With Digital Geologic Map Databases" 
below.   This digital map database, compiled from previously published data, and new 
mapping by the authors, represents the general distribution of surficial deposits in the Napa 
region.  Together with the accompanying text file (na_geo.txt or na_geo.pdf), it provides 
current information on Quaternary geology and liquefaction susceptibility of the Napa, 
California, 1:100,000 quadrangle.  The database delineates map units that are identified by 
general age and lithology following the stratigraphic nomenclature of the U.S. Geological 
Survey.  The scale of the source maps limits the spatial resolution (scale) of the database to 
1:100,000 or smaller.  The content and character of the database, as well as three methods 
of obtaining the database, are described below. 

For Those Who Aren't Familiar With Digital Geologic Map Databases

   For those interested in the Quaternary geology and liquefaction susceptibility of the Napa, 
California, 1:100,000 quadrangle who do not use an ARC/INFO compatible Geographic 
Information System (GIS), but would like to obtain the paper maps with explanation, three 
PostScript plot files and three Portable Document Format (PDF) files containing the map 
images of much of the data in the digital database, as well as the explanatory text have been 
included in separate plotfile packages (please see the section "Obtaining Plots from 
PostScript and Portable Document Format Files").
   Those interested who have computer capability can access plot file packages or the digital 
database package in any of the three ways described below.  However, it should be noted 
that the plot files do require gzip and tar utilities to access the files.  Therefore additional 
software may be required to use the plot files (please see section "Tar Files").
   For those without computer capability, you can obtain the plot file through our plot-on-
demand service for map files (please see the section "Obtaining plot from USGS Open-File 
Services) or from an outside vendor (please see the section "Obtaining Plots from an 
Outside Vendor").
DIGITAL OPEN-FILE CONTENTS

   This open-file report consists of three digital packages.  The first is the Postscript plot file 
package consisting of two PostScript plot files of the maps and a PostScript file of the 
explanatory text.  The second digital package is the Portable Document Format plot file 
package containing the same files mentioned above, but in PDF format.  A third digital 
database package consists of the geologic map database itself, and the supporting data, 
including base map, map explanation, geologic description, and references .

POSTSCRIPT PLOTFILE PACKAGE

   The  PostScript plot file package contains the images described here (see below for more 
information on Postscript plot files):

	na_plate1.ps 	A PostScript plotable file containing an image of the Quaternary 	
			geologic map with base map and key of the Napa, California, 	
			1:100,000 quadrangle.

	na_plate2.ps	A Postscript plotable file containing an image of the liquefaction
			susceptibility map with base map and key of the Napa, California,
			1:100,000 quadrangle.

	na_geo.ps	A Portable Document Format file of a report containing detailed unit
			descriptions and geological information, plus sources of data and
			references cited.

PDF PLOTFILE PACKAGE

The  PDF plot file package contains the images described here (see below for more 
information on PDF plot files):

	na_plate1.pdf	A Portable Document Format plotable file containing an image of 	
			the Quaternary geologic map with base map and key of the Napa, 	
			California, 1:100,000 quadrangle.

	na_plate2.pdf	A Portable Document Format plotable file containing an image of 	
			the liquefaction susceptibility map with base map and key of the 	
			Napa, California, 1:100,000 quadrangle.

	na_geo.pdf	A Portable Document Format file of a report containing detailed unit
			descriptions and geological information, plus sources of data and
			references cited.

DIGITAL DATABASE PACKAGE

	The digital database package includes a geologic map database file for the Napa, 
California, 1:100,000 quadrangle.  The digital maps, or coverages, along with their 
associated INFO directory have been converted to uncompressed ARC/INFO export files.  
ARC export files promote ease of data handling, and are usable by some Geographic 
Information Systems in addition to ARC/INFO (see below for a discussion of working 
with export files).  The ARC export files and the associated ARC/INFO coverages and 
directories, as well as the additional digital material included in the database package, are 
described below:

ARC/INFO		Resultant	Description of Coverage
export file		Coverage	
--------------		-----------	--------------------------------
na-geol.e00		na-geol		Depositional contacts, unit labels, and liquefaction
					susceptibility
na-hist.e00		na-hist		Historical liquefaction events.
na-index.e00		na-index_um	Topographic contours base map (from 1:100,000 	
					scale originals).
na-drain.e00		na-drain_um	Drainage base map (from 1:100,000 scale originals).
na-cult.e00		na-cult_um	Cultural and map boundary base map.

ASCII text files, including explanatory text, Postscript, and Portable Document Format files of 
formatted versions of the explanatory text, and an ARC Macro Language file for conversion of 
ARC export files into ARC coverages:

	na_geo.pdf	A Portable Document Format file of a report containing detailed unit 		
			descriptions and geological information, plus sources of data and
			references cited.
	na_geo.ps	A PostScript Format version of na_geo.pdf
	na_geo.txt	A text-only file containing an unformatted version of na_geo.pdf
	na_db.pdf	A Portable Document Format file of the data base description (this report).
	na_db.ps	A PostScript format version of na_db.pdf
	na_db.txt	A text-only file containing an unformatted version of na_db.pdf
	import.aml	ASCII text file in ARC Macro Language to convert ARC export
			files to ARC coverages in ARC/INFO.

   The following supporting directory is not included in the database package, but is 
produced in the process of reconverting the export files into ARC coverages:

	info/		INFO directory containing files supporting the 
			databases.  This directory is not included in the 
			database release, but is created in the process of 
			converting the export files into ARC coverages.


Tar Files

The three data packages are stored in tar (UNIX Tape Archive) files.  A tar utility is 
required to extract the database from the tar file.  This utility is included in most UNIX 
systems, and can be obtained free of charge via the Internet from Internet Literacy's 
Common Internet File Formats Webpage (http://www.matisse.net/files/formats.html).  The 
tar files have been compressed, and may be uncompressed with gzip, which is available 
free of charge via the Internet from the gzip Home Page (http://w3.teaser.fr/~jlgailly/gzip), 
and via links from the USGS Public Domain Software page 
(http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/public.html).  When the tar file is 
uncompressed and the data is extracted from the tar file, a directory is produced that 
contains the data in the package as described above.  The specifics of the tar files are listed 
below.

Name of 		Size of 			Directory		Data package
compressed		compressed			produced when	contained
tar file			tar file				extracted from
			(uncompressed)		tar file	
--------------		-------------------		------------------	----------------
na_ps.tar.gz		16.8 (48.7) MB		/na_ps			PostScript plotfile package

na_pdf.tar.gz		10.2 (10.2) MB		/na_pdf		PDF plotfile package

na_data.tar.gz		14.8 (52.6) MB		/na_data		digital database 
										package



PostScript Plot Files

     For those interested in the Quaternary Geology and Liquefaction Susceptibility, Napa, 
California, 1:100,000 quadrangle who do not use an ARC/INFO compatible GIS system, 
but would like to obtain the paper map with explanation, we have included a separate data 
package (na_ps.tar.gz) with three PostScript plot files containing the geologic description 
and discussion.  The plot files can be used to create a color plot of the Quaternary geologic 
map (na-plate1.ps), the Liquefaction Susceptibility map (na-plate2.ps), as well as the 
geologic description and discussion pamphlet (na_geo.ps).   These plot files are available in 
any of the three ways described below, including the World Wide Web pages.  However, 
the plot files are stored as gzip tar files requiring gzip and tar utilities to access the file.
   The PostScript images of plates 1 and 2 are 42 inches wide by 29 inches high, so it 
requires a large plotter to produce paper copies at the intended scale.   In addition to size 
constraints, some plotters, such as those with continual paper feed from a roll, are oriented 
with the long axis in the vertical direction, so the PostScript image will have to be rotated 
90 degrees to fit entirely onto the page.  Some plotters and plotter drivers, as well as many 
graphics software packages, can perform this rotation.  The geologic description and 
discussion is on 8.5 by 11 inch pages.  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 may overlap.  Sample plots by the authors have 
proven to be quite legible and useful, however.  The PostScript plotfiles for maps were 
produced by the ïpostscriptÍ command with compression set to zero in ARC/INFO version 
7.0.4.  The PostScript plotfiles for pamphlets were produced in Microsoft Word 6.0 using 
the Destination PostScript File option from the Print command.


Portable Document Format Plot Files

We have also included a separate data package (na_pdf.tar.gz) with three Portable 
Document Format(PDF) plot files containing the geologic description and discussion.  It 
contains a color plot of the Quaternary geologic map (na-plate1.pdf), the Liquefaction 
Susceptibility map (na-plate2.pdf) and the geologic description and discussion 
(na_geo.pdf).  As with the Postscript files, the plot files are stored as gzip tar files 
requiring gzip and tar utilities to access the file.
	Adobe Acrobat PDF files are similar to PostScript plot files in that they contain all 
the information needed to produce a paper copy of a map or pamphlet and they are platform 
independent.  Their principal advantage is that they require less memory to store and are 
therefore quicker to download from the Internet.  In addition, PDF files allow for printing 
of portions of a map image on a printer smaller than that required to print the entire map 
without the purchase of expensive additional software.  All PDF files in this report have 
been created from PostScript plot files using Adobe Acrobat Distiller.  In test plots we have 
found that paper maps created with PDF files contain almost all the detail of maps created 
with PostScript plot files.  We would, however, recommend that those users with the 
capability to print the large PostScript plot files use them in preference to the PDF files.
	To use PDF files, the user must get and install a copy of Adobe Acrobat Reader.  
This software is available free from the Adobe website (http://www.adobe.com).  Please 
follow the instructions given at the website to download and install this software.  Once 
installed, the Acrobat Reader software contains an on-line manual and tutorial.
	There are two ways to use Acrobat Reader in conjunction with the Internet.  One is 
to use the PDF reader plug-in with your Internet browser.  This allows for interactive 
viewing of PDF file images within your browser.  This is a very handy way to quickly 
look at PDF files without downloading them to your hard disk.  The second way is to 
download the PDF file to your local hard disk, and then view the file with Acrobat Reader.  
We strongly recommend that large map images be handled by downloading to your hard 
disk, because viewing them within an Internet browser tends to be very slow.
	To print a smaller portion of a PDF map image using Acrobat Reader, it is 
necessary to cut out the portion desired using Acrobat Reader and the standard cut and 
paste tools for your platform, and then to paste the portion of the image into a file generated 
by another software program that can handle images.  Most word processors (such as 
Microsoft Word) will suffice.  The new file can then be printed.  Image conversion in the 
cut and paste process, as well as changes in the scale of the map image, may result in loss 
of image quality.  However, test plots have proven adequate.


Database Format

The databases in this report were compiled in ARC/INFO, a commercial Geographic 
Information System (Environmental Systems Research Institute, Redlands, California), 
with version 3.0 of the menu interface ALACARTE (Fitzgibbon and Wentworth, 1991, 
Fitzgibbon, 1991, Wentworth and Fitzgibbon, 1991).  The files are in either GRID 
(ARC/INFO raster data) format or COVERAGE (ARC/INFO vector data) format.  
Coverages are stored in uncompressed ARC export format (ARC/INFO version 7.x).  
ARC/INFO export files (files with the .e00 extension) can be converted into ARC/INFO 
coverages in ARC/INFO (see below) and can be read by some other Geographic 
Information Systems, such as MapInfo via ArcLink and ESRI's ArcView (version 1.0 for 
Windows 3.1 to 3.11 is available for free from ESRI's web site:  http://www.esri.com). 
The digital compilation was done in version 7.0.4 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 AND PLOTFILE PACKAGES

The digital database and plotfile packages can be obtained in any of three ways:

	a.  From the Western Region Geologic Information Web Page.
	b.  Anonymous ftp over the Internet
	c.  Sending a tape with request


To obtain tar files of database or plotfile packages from the USGS web 
pages:

The U.S. Geological Survey now supports a set of graphical pages on the World Wide 
Web.  Digital publications (including this one) can be accessed via these pages.  The 
location of the main Web page for the entire USGS is 

	http://www.usgs.gov

The Web server for digital publications from the Western Region is 

	http://wrgis.wr.usgs.gov

Go to 

	http://wrgis.wr.usgs.gov/open-file/of98-460

to access this publication.  Besides providing easy access to the entire digital database, the 
Western Region Web page also affords easy access to the PostScript and PDF plot files for 
those who do not use digital databases.


To obtain tar files of database or plotfile packages by ftp:

The files in these reports are stored on the U.S. Geological Survey Western Region FTP 
server.  The Internet ftp address of this server is:

	ftp://wrgis.wr.usgs.gov

The user should log in with the user name ïanonymousÍ and then input their e-mail address 
as the password.  This will give the user access to all the publications available via ftp from 
this server.

The files in this report are stored in the subdirectory:

	pub/open-file/of98-460


To obtain tar files of database or plotfile packages on tape:

Database files, PostScript plotfiles, and related files can be obtained by sending a tape with 
request and return address to:

	Napa Quaternary Geology and Liquefaction
	Susceptibility 1:100,000 quadrangle PostScript Plotfile
	c/o Database Coordinator
	U.S. Geological Survey
	345 Middlefield Road, M/S 975
	Menlo Park, CA 94025

 Do not omit any part of this address!

NOTE:  Be sure to include with your request the exact names, as listed above, of the tar 
files you require. An Open-File Report number is not sufficient, unless you are requesting 
both the database package and plotfile package for the report.

The compressed tar file will be returned on the tape.  The acceptable tape types are:

	2.3 or 5.0 GB, 8 mm Exabyte tape.


Obtaining plots from USGS Open-File Services

NOTE:  As of this writing, plot-on-demand is not available from USGS.  It is anticipated 
later in 1998.

U.S. Geological Survey is planning to provide a plot-on-demand service for map files, 
such as those described in this report, through Open-File Services.  In order to obtain 
plots, contact Open-File Services at:

USGS Information Services
Box 25286
Denver Federal Center
Denver, CO 80225-0046

(303) 202-4200
1-800-USA-MAPS

FAX:  (303) 202-4695

e-mail:  infoservices@usgs.gov

Be sure to include with your request the Open-File Report number and the exact names, as 
listed in the Database Contents section above, of the plotfiles you require.  An Open-File 
Report number and its letter alone may not be sufficient, unless you are requesting plots of 
all the plotfiles for that report.


Obtaining Plots from an Outside Vendor

Those interested in Preliminary Geologic Map of the Napa 1:100,000 Quadrangle, but who 
use neither a computer nor the Internet, can still obtain the information.  We will provide 
the PostScript or Portable Document Format plot files on digital tape (details below) for use 
by commercial vendors who can make large-format plots.  Send a blank tape with request 
and return address to:

	Napa Quaternary Geology and Liquefaction
	Susceptibility 1:100,000 quadrangle PostScript Plotfiles
	c/o Database Coordinator
	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 type is:

	2.3 or 5.0 GB, 8 mm Exabyte tape.

Make sure your vendor is capable of reading this tape type and PostScript or  Portable 
Document Format plot files.  Important information regarding tape file format is included in 
the sections î ñTar Files,î "PostScript Plot Files", and "PDF Plot Files" above, so be 
certain to provide a copy of this document to your vendor.


Converting ARC export files

ARC export files are converted to ARC coverages using the ARC command IMPORT with 
the option COVER.  In order to ease conversion and to maintain naming conventions, we 
have included an ASCII text file in ARC Macro Language that will convert all of the export 
files in the database into coverages and create the associated INFO directory.  From the 
ARC command line type:

Arc:  &run import.aml

ARC export files can also be read by some other Geographic Information Systems.  Please 
consult your GIS documentation to see if you can use ARC export files and the procedure 
to import them.


ADDITIONAL INFORMATION


Digital Compilation

   The geologic map information was digitized from stable original of the geologic map at 
1:100,000 scale.  The author manuscripts (pencil on mylar) were scanned using a Altek 
monochrome scanner with a resolution of 800 dots per inch.  The scanned images were 
vectorized and transformed from scanner coordinates to projection coordinates with  digital 
tics placed by hand at map corners.  The scanned lines were edited interactively by hand 
using ALACARTE, color boundaries were tagged as appropriate, and scanning artifacts 
visible at 1:100,000 were removed. 


Base Maps

   Base Map layers were prepared from scale-stable printing negatives of the U.S. 
Geological Survey Napa, California 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 development purposes.  In addition, 
this map does not take the place of fault-rupture hazard zones designated by the California 
State Geologist (Hart and Bryant, 1997).  Similarly, the database cannot be used to identify 
or delineate landslides in the region.  For a 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 1:100,000 means that higher resolution 
information is not present in the dataset.  Plotting at scales larger than 1:100,000 will not 
yield greater real detail, although it may reveal fine-scale irregularities below the intended 
resolution of the database.  The base map layers also have a resolution of 1:100,000 and 
are provided for reference only.

DATABASE SPECIFICS

   The map databases consist of ARC coverages and supporting INFO files, which are 
stored in a Universal Transverse Mercator (California coordinate system) projection (Table 
1).
Table 1 - Map Projection

			PROJECTION UNIVERSAL
			TRANSVERSE MERCATOR	
			UNITS METERS			-on the ground
			ZONE 10				UTM zone 10

			PARAMETERS
			END

  The content of the geologic database can be described in terms of the lines, points, 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 number

LINES - 

   The lines (arcs) for na-geol are recorded as strings of vectors and are described in the arc 
attribute table (Table 3).  They define the boundaries of the map units, the boundaries of 
open bodies of water, faults, 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.

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)
SEL			1		1		I	-	user defined field 	
									used to save a 		
									selected set
SYMB			3		3		I	-	user defined field 	
									used to save symbol 	
									assignments (such 	
									as color)

Table 4 - Line Types Recorded in the LTYPE Field

contact, certain
water boundary, certain
map boundary, certain

The geologic line types 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).

AREAS - 

	Map units and liquefaction susceptibility (polygons) for na-geol 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 na_geo.txt or na_geo.pdf.  The identities of the 
liquefaction susceptibility units are recorded in the LIQ field by susceptibility label (table 
7).  Note that ARC/INFO coverages cannot contain both point and polygon information, so 
only coverages with polygon information will have a polygon attribute table, and these 
coverages will not have a point attribute table.

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

SEL			1	1		I	-	user defined field used 	
								to save a selected set
SYMB			3	3		I	-	user defined field used 	
								to save symbol 		
								assignments (such as 		
								color)
LIQ			8	8		C		liquefaction susceptibility

Table 6 - Map Units
(See na_geo.txt or na_geo.pdf for descriptions of units)


    						
af
Qhbm/af
Qhbm
Qhay
Qhay/Qhb
Qhb
Qhs
Qht
Qhf
Qha
Qs
Qb
Qt
Qf
Qa
Qpt
Qpf
Qpa
Qpmt
Qoa
Qomt
w
	      br




Table 7 - Susceptibility Units
The susceptibility units are VH = very high, H = high, M-H = medium to high, M = 
medium, L-H = low to high, L-M = low to medium, L = low, VL = very low,
and w = water


    						
VH
H
M-H
M
L-H
L-M
L
VL
	      w



POINTS -

	Historical Liquefaction Events (points), for na-hist, are described in the point 
attribute table (Table 8).  They define the location of liquefaction events.  The identities of 
the points are recorded in the LOCATION#, YEAR, PROBABLE_UNIT, and PTTYPE 
field  These field correspond to data found in na_geo.txt or na_geo.pdf table 2.  The 
identities for the PTTYPE field can be found in table 9.

Table 8 - Content of the Point Attribute Tables

ITEM NAME         WIDTH  OUTPUT     TYPE    N. DEC

AREA			4	12		F	3	not used

PERIMETER		4	12		F	3	not used

<coverage>#		4	5		B	-	unique internal 		
								control number
<coverage>-ID	4	5		B	-	unique identification 		
								number
LOCATION#		3	3		I		location identification
								number
YEAR			10	10		C		year of event

PROBABLE_UNIT	35	35		C		geologic unit of event

PTTYPE		35	35		C		type of event


Table 9 - PTTYPE Field


    						
Lateral spreading
Ground settlement
Sand boil
Ground cracks
Absence of cracks
	      Miscellaneous effects




Acknowledgments

   Carl M. Wentworth, Todd T. Fitzgibbon, and Geoffrey A. Phelps graciously provided 
assistance with Alacarte and ARC/INFO.  The scanning and editing of the digital maps was 
done by Thomas E. May and Carolyn E. Randolph.  Earl E. Brabb provided much helpful 
advice and feedback, as well as arranging for material support for the project.

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.
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