Digital Images of Official Maps of Alquist-Priolo Earthquake Fault Zones of California, Northern and Eastern Region By DMG Staff California Department of Conservation Division of Mines and Geology 1 READ-ME FILE DIGITAL IMAGES OF OFFICIAL ALQUIST-PRIOLO EARTHQUAKE FAULT ZONES MAPS OF CALIFORNIA, NORTHERN AND EASTERN REGION INTRODUCTION The Alquist-Priolo Earthquake Fault Zoning (AP) Act was passed in 1972 as a result of the destructive 1971 San Fernando earthquake. The AP Act addresses the seismic hazard of surface fault rupture by prohibiting the placement of most structures for human occupancy across traces of active faults. The AP Act addresses the seismic hazard of surface fault rupture by prohibiting the placement of most structures for human occupancy across traces of active faults. The Act also requires sellers and real estate agents to inform buyers whether real property being sold is within a state- designated Earthquake Fault Zone. The Department of Conservation, Division of Mines and Geology has issued 544 regulatory maps as of March 1, 2000 at a scale of 1:24,000. These maps, designated as Earthquake Fault Zones maps, are issued in order to assist cities and counties in avoiding the hazard of surface fault rupture. For more information on the AP Act refer to the enclosed .pdf version of Special Publication (SP) 42, Fault-Rupture Hazard Zones in California. The statewide collection of digital images of AP Earthquake Fault Zone maps is divided into three geographic regions: Southern Region, Central Coastal Region, and Northern and Eastern Region. This CD contains digital images of Official Maps of Earthquake Fault Zones (EFZ) affecting the Northern and Eastern Region, including Alpine, Butte, Humboldt, Inyo, Lassen, Mendocino, Modoc, Mono, Shasta, and Siskiyou counties, and is current as of March 1, 2000. Updates of digital versions of Earthquake Fault Zone maps will be available on the Department of Conservation, Division of Mines and Geology’s (DMG) web site as new maps are issued and current maps are revised. New and/or revised EFZ maps generally are issued about once a year. Release announcements of both preliminary review maps and official EFZ maps can be found at www.consrv.ca.gov/dmg/rghm. LICENSE AGREEMENT ©2000 California Department of Conservation, Division of Mines and Geology. All rights reserved. No part of this CD-ROM may be reproduced, transmitted, or distributed in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of the Division of Mines and Geology except as follows. Permission is granted to reproduce prints of all or part of the data under the following conditions: 1) For personal use 2) For publication in a report in unmodified form, cite on figure or in text as “Reproduced with permission. California Division of Mines and Geology CD-ROM 2000-00x 2 (2000), Official Map of Alquist-Priolo Earthquake Fault Zones, {name of} Quadrangle (19xx).” (3) For publication in a report in modified form, cite on figure or in text as “Modified from California Division of Mines and Geology from CD-ROM 2000-00x (2000), Official Map of Alquist-Priolo Earthquake Fault Zones, {name of} Quadrangle (19xx).” CD CONTENTS Contents of this CD include 169 pdf image files of Official Maps of Alquist- Priolo Earthquake Fault Zones and metadata files for the Northern and Eastern Region. Special Publication (SP) 42, Fault-Rupture Hazard Zones in California (1999 reprinted version of 1997 edition), is included as a pdf file. This CD-ROM contains four tables in pdf file format. Table 1 is an alphabetical listing of EFZ map names listing the affected county(ies) and city (ies). Table 2 lists the 36 affected counties and the specific EFZ maps that affect that county. Table 3 lists the 100 affected cities and the specific EFZ maps affecting that city. Table 4 lists the counties contained in each of the CD-ROM sets. Please note that the tables of affected counties (Table 2) and affected cities (Table 3) are correct as of March 2000, but may be subject to change as new cities are created, city boundaries are expanded, or new zones are established. Current lists of counties and cities affected by AP EFZs are located at DOC\DMG’s website www.consrv.ca.gov/dmg/rghm. The EFZ files contained in this CD are current as of March 1, 2000. Please check the DMG website at www.consrv.ca.gov/dmg/rghm for current information on new and revised EFZ maps. Original AP EFZ maps (original hardcopy maps) consist of a topographic base map at 1:24,000 scale and a clear-film overlay containing turning points defining EFZ boundaries and fault traces used to establish the EFZ. Fault traces consist of five line types: Solid line: accurately located trace Long-dashed line: approximately located trace Short-dashed line: inferred fault trace Dotted line: concealed fault trace Thin dashed and dotted line: indicates aerial photo lineament (symbol generally not used after 1981) Query: indicates additional uncertainty The Act was initially designated Alquist-Priolo Special Studies Zones Act and official regulatory maps were known as maps of Special Studies Zones. The name was changed January 1, 1994 to Alquist-Priolo Earthquake Fault Zoning Act and the official maps are currently referred to as maps of Earthquake Fault Zones. Title blocks of maps issued prior to 1994 refer to the older name Special Studies Zones. These pre-1994 maps have been reproduced for this CD without the stamp referring to the name change. 3 DIGITAL COMPILATION The original hardcopy maps used to reproduce Official Maps of Earthquake Fault Zones were the basis for developing these digital image files. Each hardcopy map consists of two layers: a solid line clear film topographic base and a clear film overlay containing EFZ zones and fault traces. Each layer was scanned at 400 dpi using an Anatech large-format scanner. The base and overlay images were translated to .pcx grayscale images and resolution reduced to 266 dpi and reduced to 50% of the physical image size. These reductions in size and resolution allowed smaller file sizes with negligible loss of image quality. The resulting .pcx files were then registered, enhanced, and processed to .pdf files using Adobeâ Photoshopâ and Adobeâ Acrobatâ The final Acrobat images are optimized to read in Adobeâ Acrobatâ Reader, version 4.0. GETTING STARTED You must have Adobe Acrobat Reader 4.0 installed before you can view the EFZ images. The .pdf files on this CD-ROM are exact images of the Official Maps of Earthquake Fault Zones issued by the Division of Mines and Geology. These images are intended for viewing and printing at a scale of 1 inch equals 2,000 feet. Any further enlargement could result in a lesser quality image. SETTING UP YOUR ACCROBAT READER Inserting the CD-ROM (only when using a windows pc) will automatically open a window with navigation buttons to start your session. When first opening the Acrobat Reader, select “file”, “preferences”, “general” and unselect the option to open cross-doc links in the same window. Deselecting this option allows multiple window operation. You may also need to configure your Internet Browser using weblink preferences in Acrobat Reader. NAVIGATING THE CD FILES The individual county index maps show all of the EFZ maps that affect that county. At the main index map, selecting either a specific county on the index map, or the county name in the list to the left will access the specific county index map. If your view is showing the thumbnails or bookmarks as a list, you may also double-click these to navigate to the desired county. Each county map has arrow indicators to access the adjacent county. However, if the arrow points to a county or map not contained in this CD-ROM, nothing will happen. An Acrobat sticky-note will indicate what action to take. You will have to purchase the CD-ROM that contains that county from the Division of Mines and Geology. Refer to Table 4 for a list of counties contained in each CD-ROM set. To find a specific EFZ map, you need to know the geographic location of the area, the city name, or the quadrangle map name. Affected cities are listed in Table 3 and are shown to the left of each county index. Clicking on the city name in this list on the 4 county index maps will access the correct EFZ map. If an incorporated city is not listed in Table 3, it is not affected by an EFZ. If an EFZ on a specific quadrangle map extends to the adjacent quadrangle contained in this CD-ROM, clicking on the area outside of the map border will directly access the adjacent EFZ map. SELECTING AND PRINTING A SPECIFIC AREA ON AN EFZ MAP Any portion of these maps can be selected and copied for use in any application using the paste command. To select an area, open the document and zoom to 100% at the area of interest. Hold the mouse button down on the “grab text” tool button, which will expand to three buttons. Choose the “grab graphics” tool button (last one on the right). Using this tool, select your area of interest. Now use the zoom box to enter “200%” as zoom number, then copy the selection. Using 200% will result in a image at approximately the original map scale (1:24,000) that can be copied into the desired application. To print the selected area at a scale of 1 inch equals 2,000 feet requires printing at 200% enlargement. The image was reduced 50% to reduce file size attributes, while maintaining image quality for viewing.