1560 U~S.l'lep'.rtment 0 die Interior u.s. Geologicol Surv. Cover. Insert, ground-shaking damage from the 1949 Puget Sound earthquake to unrein- forced masonry in Seattle, Wash. Photograph by George Cankonen, Seattle Times. Back- ground, landslide damage to the railbed between Olympia and Tumwater, Wash., in the 1965 Puget Sound earthquake. Photograph by Greg Gilbert, Daily Olympian. Cover design by Carol A. Quesenberry. Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest Albert M. Rogers, Timothy J. Walsh, William J. Kockelman, and George R. Priest, Editors Volume 2 T OF EN TH U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1560 TM E R I A N P T E E D R . I O S . R An investigation of the earthquake potential in the U Pacific Northwest and examination of the measures necessary to reduce seismic hazards M 9 A 8 4 R C H 3, 1 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1998 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director For sale by U.S. Geological Survey, Information Services Box 25286, Federal Center Denver, CO 80225 Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Library of Congress Cataloging-in-Publication Data Assessing earthquake hazards and reducing risk in the Pacific Northwest / Albert M. Rogers...[et al.], editors. p. cm.—(U.S. Geological Survey professional paper ; 1560) Includes bibliographical references. Supt. of Docs. no.: I 19.16:1560 1. Earthquake hazard analysis—Northwest, Pacific. 2. Earthquakes—Northwest, Pacific. I. Rogers, A.M. II. Series. QE535.2.U6A825 1997 363.3′495—dc20 ISBN 0-607-89262-5 95–37559 CIP CONTENTS VOLUME 2 EARTHQUAKE HAZARDS An Introduction to Predicting Earthquake Hazards and Losses in the Pacific Northwest By Albert M. Rogers and George R. Priest................................................ 307 GROUND-MOTION PREDICTION Engineering Characterization of Earthquake Strong Ground Motions in the Pacific Northwest By Walter J. Silva, Ivan G. Wong, and Robert B. Darragh ......................... 313 Simulated Strong Ground Motions for Magnitude 8 Earthquakes on the Cascadia Subduction Zone By Brian Cohee and Paul Somerville.......................................................... 325 Earthquake Ground-Response Studies in West and South Seattle, Washington By David L. Carver, Kenneth W. King, Robert A. Williams, and David M. Worley ................................................................................. 345 Earthquake-Hazard Geologic Maps of the Portland, Oregon, Metropolitan Area By Ian P. Madin ........................................................................................ 355 GROUND FAILURE Ground Failure Associated with the Puget Sound Region Earthquakes of April 13, 1949, and April 29, 1965 By Alan F. Chleborad and Robert L. Schuster ............................................ 373 Evaluation of Liquefaction Potential in Seattle, Washington By W. Paul Grant, William J. Perkins, and T. Leslie Youd.......................... 441 IMPLEMENTATION Reducing Earthquake Hazards—An Introduction By William J. Kockelman............................................................................ 477 Techniques for Reducing Earthquake Hazards By William J. Kockelman............................................................................ 479 Earthquake Risk-Reduction Prospects for the Puget Sound and Portland, Oregon, Areas By Peter J. May ........................................................................................... 497 Integrated Tsunami-Hazard Assessment for a Coastal Community, Grays Harbor, Washington By Jane Preuss and Gerald T. Hebenstreit .................................................. 517 Approaches to Seismic-Hazard Mitigation by Local Governments—An Example from King County, Washington By Derek B. Booth and John P. Bethel ....................................................... 537 Liability for Earthquake Hazards or Losses and its Impacts on the Cities and Counties of Washington By Jeanne B. Perkins and Kenneth K. Moy................................................ 543 III IV CONTENTS TABLE OF CONVERSION FACTORS Multiply By To obtain Area square meter (m2) 10.76 square foot (ft2) square kilometer (km2) 0.3861 square mile (mi2) Density gram per cubic centimeter (g/cm3) 62.43 pound per cubic foot (lb/ft3) Length millimeter (mm) 0.03937 inch (in.) centimeter (cm) 0.3937 inch (in.) meter (m) 3.281 foot (ft) kilometer (km) 0.6214 mile (mi) kilometer (km) 0.5400 mile, nautical (nmi) Volume cubic centimeter (cm3) 0.06102 cubic inch (in.3) cubic meter (m3) 35.31 cubic foot (ft3) cubic kilometer (km3) 0.2399 cubic mile (mi3) Abbreviations: ka, thousand years ago; Ma, million years ago EARTHQUAKE HAZARDS Preceding page. Insert, debris left by the April 29, 1965, Seattle, Wash., earthquake. Photograph courtesy of NOAA/EDIS. Background, destruction caused by the fall of an unbraced masonry parapet in downtown Klamath Falls, Oreg., during the Sept. 20, 1993, M 5.9 and M 6.0 earthquakes. Photograph by Lou Sennick of the Herald and News, Klamath Falls, Oreg. (from Dewey, J.W., 1993, Damages from the 20 September earth- quakes near Klamath Falls, Oregon: Earthquakes & Volcanoes, v. 24, no. 3, p. 121–128). AN INTRODUCTION TO PREDICTING EARTHQUAKE HAZARDS AND LOSSES IN THE PACIFIC NORTHWEST By Albert M. Rogers1 and George R. Priest2 INTRODUCTION called paleoseismology has emerged that provides informa- tion about recurrence rates on faults and the time since the The articles in the Earthquake Hazards section of the last earthquake, data that can be incorporated into probabi- professional paper discuss ground-shaking and listic ground-motion maps or used to forecast the probabil- ground-failure hazards and the estimation of losses associ- ity of the next earthquake during a chosen time interval. ated with these hazards. Ground shaking and ground failure Database development will also be of great value in contin- are the major factors in loss of life and property during earth- ued research to improve hazards-prediction methodology. quakes. The delineation of these hazards by mapping and Site-specific hazard estimates are most useful in the site-specific prediction techniques is an important step in the design of critical facilities and high-occupancy buildings process of reducing the effects of earthquakes. Ground-shak- such as bridges, power plants, hospitals, and high-rise ing and ground-failure maps, for example, can be valuable in structures. The information used for site-specific estimates land-use-policy development, siting or relocation of local is generally more detailed than that required to produce haz- government emergency facilities, and urban-renewal deci- ard maps. Such estimates are commonly based on borehole sions. Furthermore, hazard maps can aid in the design and measurements at the site and modeling of local ground siting of lifelines (see volume 1, Glossary) and ordinary motions based on these measurements and also on data such structures and in emergency planning and response, each as regional ground-motion attenuation and fault locations. requiring advance information about the likelihood of earth- Estimating ground-shaking and ground-failure hazards quake damage to infrastructure. Estimates of the magnitude in this region is complicated by three factors. First, several of economic losses and mortality during future earthquakes types of earthquakes are likely (see Rogers and others, vol- are also partly based on hazard maps. Loss estimates are not ume 1, for a discussion of earthquake types), and each type is only useful in planning for earthquakes but also serve deci- expected to produce damage that differs in geographic distri- sion makers in establishing preventive actions and determin- bution and level of intensity. Second, very few ing the rate at which resources should be expended to reduce strong-motion records exist that would permit calibration of earthquake effects. models or generalization about the characteristics of ground shaking for the region. Furthermore, no records exist for the Preparation of hazard maps requires extensive regional types of Pacific Northwest earthquakes having the greatest development of databases, a process that is far from potential for destruction, that is, the great Cascadia complete in the Pacific Northwest. Useful hazard maps, for thrust-fault earthquake and the shallow continental-crust example, are based on detailed mapping of geologic earthquake. Third, the types of data needed to produce deposits and measurement of their physical properties and microzonation maps for strong motion, ground failure, and on topography, sediment thickness, basin geometry, losses are not yet available except in limited areas. water-table depth, attenuation of ground motion, and the Nevertheless, some estimates of these factors are seismic and geologic mapping of young faults capable of possible. This volume presents work to develop several producing damaging earthquakes. A new earth-science field types of databases, research to predict site-specific estimates ________________ of ground shaking for several earthquake types, research to 1U.S. Geological Survey, Box 25046, MS 966, Federal Center, Denver, CO 80225. map limited areas that depict some types of ground failure, 2Oregon Department of Geoscience, 910 State Office Building, 1400 and the estimation of one type of economic loss. In the S.W. 5th Ave., Portland, OR 97201. following, we review the