State of Oregon Oregon Department of Geology and Mineral Industries Brad Avy, State Geologist OPEN-FILE REPORT O-19-09 COSEISMIC LANDSLIDE SUSCEPTIBILITY, LIQUEFACTION SUSCEPTIBILITY, AND SOIL AMPLIFICATION CLASS MAPS, CLACKAMAS, COLUMBIA, MULTNOMAH, AND WASHINGTON COUNTIES, OREGON FOR USE IN HAZUS: FEMA'S METHODOLOGY FOR ESTIMATING POTENTIAL LOSSES FROM DISASTERS By Christina A. Appleby, William J. Burns, Robert W. Hairston-Porter, and John M. Bauer 2019 Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street, Suite 965, Portland, OR 97232 Coseismic Geohazard Maps, Clackamas, Columbia, Multnomah, and Washington Counties, Oregon DISCLAIMER This product is for informational purposes and may not have been prepared for or be suitable for legal, engineering, or surveying purposes. Users of this information should review or consult the primary data and information sources to ascertain the usability of the information. This publication cannot substitute for site-specific investigations by qualified practitioners. Site-specific data may give results that differ from the results shown in the publication. Expires 12/31/2020 Oregon Department of Geology and Mineral Industries Open-File Report O-19-09 Published in conformance with ORS 516.030 For additional information: Administrative Offices 800 NE Oregon Street, Suite 965 Portland, OR 97232 Telephone (971) 673-1555 https://www.oregongeology.org/ https://oregon.gov/DOGAMI/ Oregon Department of Geology and Mineral Industries Open-File Report O-19-09 ii Coseismic Geohazard Maps, Clackamas, Columbia, Multnomah, and Washington Counties, Oregon TABLE OF CONTENTS 1.0 Report Summary .............................................................................................................................................. 1 2.0 Introduction ..................................................................................................................................................... 2 2.1 Study area ......................................................................................................................................................... 2 2.2 Purpose ............................................................................................................................................................. 4 2.3 Coseismic Hazards ............................................................................................................................................ 4 2.3.1 Soil Amplification .................................................................................................................................... 4 2.3.2 Liquefaction ............................................................................................................................................ 6 2.3.3 Landslides ............................................................................................................................................... 7 2.4 Coseismic Hazard Studies in the Portland Regional Area ................................................................................. 7 3.0 Methods .......................................................................................................................................................... 9 3.1 Methodology Overview .................................................................................................................................... 9 3.2 Unified Geologic Map ..................................................................................................................................... 11 3.3 Landslide Susceptibility .................................................................................................................................. 16 3.4 Soil Amplification Class ................................................................................................................................... 20 3.5 Liquefaction Susceptibility .............................................................................................................................. 21 4.0 Results ........................................................................................................................................................... 25 4.1 Soil Amplification Class ................................................................................................................................... 25 4.2 Liquefaction Susceptibility .............................................................................................................................. 27 4.3 Coseismic Landslide Susceptibility .................................................................................................................. 29 5.0 Discussion, Conclusions, and Recommendations ........................................................................................... 32 5.1 Recommendations .......................................................................................................................................... 32 5.2 Limitations ...................................................................................................................................................... 33 6.0 Acknowledgments ......................................................................................................................................... 34 7.0 References ..................................................................................................................................................... 35 Appendix A. Applications of Maps within Hazus .................................................................................................. 39 Appendix B. Geologic Unit Classification .............................................................................................................. 42 Oregon Department of Geology and Mineral Industries Open-File Report O-19-09 iii Coseismic Geohazard Maps, Clackamas, Columbia, Multnomah, and Washington Counties, Oregon LIST OF FIGURES Figure 1. Map of the study area .............................................................................................................................. 3 Figure 2. Schematic diagram of soil amplification effects on bedrock versus soft soils ......................................... 5 Figure 3. Damage to a 21-story, steel-constructed apartment complex in Mexico City after the September 19, 1985, earthquake ............................................................................................................ 5 Figure 4. Examples of liquefaction damage from the February 2011 Christchurch earthquake ............................ 6 Figure 5. Road prism rotational type landslide (top) and lateral spread landslide along the shoreline of Capitol Lake Olympia, Washington (bottom) ........................................................................................... 7 Figure 6. Flowchart summarizing methodology used to create soil amplification class, liquefaction susceptibility, and landslide susceptibility maps .................................................................................... 10 Figure 7. Principal sources of geologic data for the study area ............................................................................ 12 Figure 8. Example of interpreted geologic unit contacts underlying mapped landslides ..................................... 13 Figure 9. Lidar acquisition dates for study area .................................................................................................... 15 Figure 10. Sources of landslide data ....................................................................................................................... 18 Figure 11. Soil amplification class map ................................................................................................................... 26 Figure 12. Liquefaction susceptibility ...................................................................................................................... 28 Figure 13. Coseismic landslide susceptibility given dry groundwater conditions ................................................... 30 Figure 14. Coseismic landslide susceptibility given wet groundwater conditions .................................................. 31 Figure 15. Summary of application of liquefaction susceptibility maps within Hazus ............................................ 40 Oregon Department of Geology and Mineral Industries Open-File Report O-19-09 iv Coseismic Geohazard Maps, Clackamas, Columbia, Multnomah, and Washington Counties, Oregon LIST OF TABLES Table 1. Notes on quality and applicability of principal sources for geologic data.............................................. 11 Table 2. Landslide units removed from geologic maps ....................................................................................... 14 Table 3. Landslide susceptibility for (a) dry and (b) wet conditions .................................................................... 16 Table 4. Generalized geologic unit type associated with landslide geologic groups ........................................... 19 Table 5. NEHRP site classes .................................................................................................................................. 20 Table 6. Generalized geologic unit type associated with NEHRP classes............................................................. 21 Table 7. Liquefaction susceptibility rating systems ............................................................................................