README INFORMATION FOR EARTHQUAKE SCENARIO AND PROBABILISTIC GROUND SHAKING MAPS FOR THE PORTLAND, OREGON, METROPOLITAN AREA, CD-ROM DISK This compact disc contains digital files for Interpretive Map Series IMS-16, "Earthquake scenario and probabilistic ground shaking maps for the Portland, Oregon, metropolitan area." This publication is issued by the Oregon Department of Geology and Mineral Industries. The publication is available from The Nature of the Northwest Information Center Suite 177 800 NE Oregon Street Portland, OR 97232-2162 503/872-2750 Fax 503/731-4066 http://www.naturenw.org and the Baker City and Grants Pass, Oregon, field offices of the Oregon Department of Geology and Mineral Industries. Title and authorship IMS-16, Earthquake scenario and probabilistic ground shaking maps for the Portland, Oregon, metropolitan area by Ivan Wong, Walter Silva, Jacqueline Bott, Douglas Wright, Patricia Thomas, Nick Gregor, Sylvia Li, Matthew Mabey, Anna Sojourner, and Yumei Wang. Eleven maps are included in this publication: (digital map file name in parentheses) Sheet 1 Earthquake scenario ground shaking map for the Portland, Oregon, metropolitan area, Portland Hills fault M 6.8 earthquake, 0.2 sec spectral acceleration at the ground surface (m68_5hz) Sheet 2 Earthquake scenario ground shaking map for the Portland, Oregon, metropolitan area, Portland Hills fault M 6.8 earthquake, 1.0 sec spectral acceleration at the ground surface (m68_1hz) Sheet 3 Earthquake scenario ground shaking map for the Portland, Oregon, metropolitan area, Cascadia subduction zone M 9.0 earthquake, peak horizontal acceleration at the ground surface (m90_pga) Sheet 4 Earthquake scenario ground shaking map for the Portland, Oregon, metropolitan area, Cascadia subduction zone M 9.0 earthquake, 0.2 sec horizontal spectral acceleration at the ground surface (m90_5hz) Sheet 5 Earthquake scenario ground shaking map for the Portland, Oregon, metropolitan area, Cascadia subduction zone M 9.0 earthquake, 1.0 sec horizontal spectral acceleration at the ground surface (m90_1hz) Sheet 6 Probabilistic earthquake ground shaking map for the Portland, Oregon metropolitan area, 10% probability of exceedance in 50 years, peak horizontal acceleration at the ground surface (500yrs_pga) Sheet 7 Probabilistic earthquake ground shaking map for the Portland, Oregon metropolitan area, 10% probability of exceedance in 50 years, 0.2 sec horizontal spectral acceleration at the ground surface (500yrs_5hz) Sheet 8 Probabilistic earthquake ground shaking map for the Portland, Oregon metropolitan area, 10% probability of exceedance in 50 years, 1.0 sec horizontal spectral acceleration at the ground surface (500yrs_5hz) Sheet 9 Probabilistic earthquake ground shaking map for the Portland, Oregon, metropolitan area, 2% probability of exceedance in 50 years, peak horizontal acceleration at the ground surface (2500yrs_pga) Sheet 10 Probabilistic earthquake ground shaking map for the Portland, Oregon, metropolitan area, 2% probability of exceedance in 50 years, 0.2 sec horizontal spectral acceleration at the ground surface (2500yrs_5hz) Sheet 11 Probabilistic earthquake ground shaking map for the Portland, Oregon, metropolitan area, 2% probability of exceedance in 50 years, 1.0 sec horizontal spectral acceleration at the ground surface (2500yrs_1hz) Files Apart from this README file, all data are grouped into three folders: "Maps," "Text," and "Metadata." "Text" folder: Contains the complete explanatory "text-only" material in -.txt format (IMS-16-CDtx.txt) and illustrations and tables separately in -.jpg, -.tif, and -.xls formats. The text includes an introduction, hazard map explanation and methodology, and source information. "Maps" folder: The digital map files are presented as raster images and vector files. The digital image map files are in JPEG format. Vector files are available in two formats: (1) .tab - native file format of MapInfo GIS software package by MapInfo Corporation of Troy, New York. (2) .shp - native file format of ArcView GIS software package by ESRI, Redlands, California. Note: All map files are in Transverse Mercator projection, NAD 1927, Zone 10, meters "Metadata" folder: The metadata.txt is a documentation of the digital map dataset. Data viewing Most files can be viewed with a variety of software systems. For the vector map data, both program manufacturers currently offer viewer software that can be downloaded free: http://www.esri.com/software/arcexplorer/index.html http://www.mapinfo.com/software/proviewer/index.html LIMITATIONS There are large uncertainties associated with ground motion prediction in the Pacific Northwest due to a limited amount of region-specific information and data on the characteristics of seismic sources and ground motions. In the portrayal of the Cascadia subduction zone scenario, the uncertainties in the geometry and eastward extent of the rupture are particularly large. Additional uncertainty stems from the characterization of the subsurface geology beneath Portland and the estimation of the associated site response effects on ground motions. Thus the maps should not be used for site-specific design or in place of site-specific hazard evaluations.