Special Paper 32A SUMMARY OFSPECIALPAPER 31:MITIGATING GEOLOGIC HAZARDS INOREGON:A TECHNICAL REFERENCE MANUALByJohn D. Beaulieu and Dennis OlmsteadOregon Department of Geology and Mineral Industries1999Geologic Hazards:Reducing Oregon’s LossesOregon Department of Geology and Mineral Industries Special Papers, ISSN 0278–3703Published in conformance with ORS 516.030This publication is a summary of the Oregon Department of Geology and MineralIndustries’ Special Paper 31: Mitigating geologic hazards in Oregon:A technical refer-ence manual, which contains more complete information about natural hazards inOregon and how to mitigate them.For copies of these publications or other information about Oregon’s geology andnatural resources, contact:Nature of the Northwest Information Center800 NE Oregon Street #5Portland, Oregon 97232(503) 872-2750http://www.naturenw.orgSPECIAL PAPER 32Geologic Hazards:Reducing Oregon’s Losses byJohn D. Beaulieu, State GeologistandDennis L. Olmstead, Deputy State GeologistOregon Department of Geology and Mineral Industries1999STATE OF OREGONDEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIESJohn D. Beaulieu, State GeologistTable of contentsExecutive summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Why a technical reference manual? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Recognize that geologic hazards are a growing problem . . . . . . . . . . . . . . . . . . . . . .3Properly characterize the geologic hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Create an equitable team of stakeholders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Know the specific reason for the strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Strategies are community specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Select from a range of strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Make the strategy permanent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Proceed with perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Appendix 1: The diversity of geologic hazards in Oregon . . . . . . . . . . . . . . . . . . . . . .7Appendix 2: Selected geologic disaster events in Oregon . . . . . . . . . . . . . . . . . . . . . .8Appendix 3: Damage from geologic hazards in Oregon . . . . . . . . . . . . . . . . . . . . . . .9Appendix 4: Specific hazard characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Appendix 5: Multi-hazard relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Appendix 6: Geologic hazard risk reduction by state and local agencies . . . . . . . .14Appendix 7: Range of strategies to reduce risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Appendix 8: Concluding questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Floods are one of Oregon’s most common natural disasters, affecting homes, businesses, farms, roadsand railroads.Special Paper 32—Geologic Hazards: Reducing Oregon’s Losses 1Executive summaryThe science of geology tells us that natural disas-ters of the future will exceed those that we haveexperienced in our brief written history.Oregon has a variety of geologic hazards includ-ing landslides, debris flows, floods, earthquakes,volcanoes, tsunamis, and erosion. The risks posed by these hazards can be man-aged so that the benefits achieved are acceptablein terms of costs. The keys to managing the riskare having enough information about the hazardand taking the proper steps in risk reduction. Reducing risks from geologic hazards involvesseveral steps. These are: • Properly characterizing the hazard;• Building a team to develop strategies;• Considering a range of strategies to addressthe risk;• Choosing the appropriate strategies from abroad range of choices;• Permanent integration of the strategies toassure ongoing success.Community efforts that do not include each ofthese steps may not be fully effective. There maybe adequate information about a hazard, butunacceptable strategies are proposed.Alternatively, strategies may be acceptable, butmay not be effective, because the hazard was notfully understood. Other reasons why strategiesmay be ineffective are:• Strategies may develop good informationabout hazards butdo not link to riskreduction actions.• Strategies mayinclude actionsreducing risk butnot adequatelycharacterize thehazards.• Strategies mayplace the burdenfully on local government without benefit oftechnology transfer or proper technical infor-mation from sources better able to providescientific and technical information.• Strategies may place the emphasis on interac-tion and process but not on understandingthe hazard or finding the most effective riskreduction methods.In Oregon, there are many opportunities toreduce risks from geologic hazards. Land usestatutes and goals, building code regulations,construction practice manuals, public education,and voluntary actions have equally importantroles in risk reduction.Processes for imple-menting risk reduc-tion may include ruledevelopment, com-prehensive plans,periodic review ofplans, ordinancedevelopment, publiceducation, or otherstrategies by a vari-ety of agencies.The focus of this manual is to present the haz-ards and insights and information on how theycan best be understood and managed from atechnical and a risk-management point of view.It includes basic elements that should be presentin any effective regulatory or decision makingprocess.Landslides are a common problem throughoutOregon. This 1996 landslide in Portland’s WestHills directly affected at least four lots and tworoads. The major …
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