Geologic Hazards Reducing Oregon s Losses Special Paper 32 A SPECIAL PAPER 31 GEOLOGIC HAZARDS IN OREGON SUMMARY OF MITIGATING A TECHNICAL REFERENCE MANUAL By John D Beaulieu and Dennis Olmstead Oregon Department of Geology and Mineral Industries 1999 Oregon Department of Geology and Mineral Industries Special Papers ISSN 0278 3703 Published in conformance with ORS 516 030 This publication is a summary of the Oregon Department of Geology and Mineral Industries Special Paper 31 Mitigating geologic hazards in Oregon A technical reference manual which contains more complete information about natural hazards in Oregon and how to mitigate them For copies of these publications or other information about Oregon s geology and natural resources contact Nature of the Northwest Information Center 800 NE Oregon Street 5 Portland Oregon 97232 503 872 2750 http www naturenw org SPECIAL PAPER 32 Geologic Hazards Reducing Oregon s Losses by John D Beaulieu State Geologist and Dennis L Olmstead Deputy State Geologist Oregon Department of Geology and Mineral Industries 1999 STATE OF OREGON DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES John D Beaulieu State Geologist Table of contents Executive summary 1 Why a technical reference manual 2 Recognize that geologic hazards are a growing problem 3 Properly characterize the geologic hazards 3 Create an equitable team of stakeholders 4 Know the specific reason for the strategy 4 Strategies are community specific 4 Select from a range of strategies 5 Make the strategy permanent 5 Proceed with perspective 6 Appendix 1 The diversity of geologic hazards in Oregon 7 Appendix 2 Selected geologic disaster events in Oregon 8 Appendix 3 Damage from geologic hazards in Oregon 9 Appendix 4 Specific hazard characterization 11 Appendix 5 Multi hazard relationships 13 Appendix 6 Geologic hazard risk reduction by state and local agencies 14 Appendix 7 Range of strategies to reduce risk 15 Appendix 8 Concluding questions 27 Floods are one of Oregon s most common natural disasters affecting homes businesses farms roads and railroads Executive summary The science of geology tells us that natural disasters of the future will exceed those that we have experienced in our brief written history Oregon has a variety of geologic hazards including landslides debris flows floods earthquakes volcanoes tsunamis and erosion The risks posed by these hazards can be managed so that the benefits achieved are acceptable in terms of costs The keys to managing the risk are having enough information about the hazard and taking the proper steps in risk reduction Reducing risks from geologic hazards involves several steps These are Properly characterizing the hazard Building a team to develop strategies Considering a range of strategies to address the risk Choosing the appropriate strategies from a broad range of choices Permanent integration of the strategies to assure ongoing success Landslides are a common problem throughout Oregon This 1996 landslide in Portland s West Hills directly affected at least four lots and two roads The major damage occurred to the house located across the street from the slide Community efforts that do not include each of these steps may not be fully effective There may be adequate information about a hazard but unacceptable strategies are proposed In Oregon there are many opportunities to Alternatively strategies may be acceptable but may not be effective because the hazard was not reduce risks from geologic hazards Land use statutes and goals building code regulations fully understood Other reasons why strategies construction practice manuals public education may be ineffective are and voluntary actions have equally important Strategies may develop good information roles in risk reduction about hazards but do not link to risk Processes for implereduction actions menting risk reducA firm basis for action includes tion may include rule Strategies may Characterizing the hazard development cominclude actions Using a carefully selected team prehensive plans reducing risk but periodic review of not adequately Considering a range of strategies plans ordinance characterize the Selecting the best strategy development public hazards Institutionalizing the strategy education or other Strategies may strategies by a variplace the burden ety of agencies fully on local government without benefit of technology transfer or proper technical information from sources better able to provide scientific and technical information Strategies may place the emphasis on interaction and process but not on understanding the hazard or finding the most effective risk reduction methods The focus of this manual is to present the hazards and insights and information on how they can best be understood and managed from a technical and a risk management point of view It includes basic elements that should be present in any effective regulatory or decision making process Special Paper 32 Geologic Hazards Reducing Oregon s Losses 1 Why a technical reference manual Oregon has among the widest variety of significant geologic hazards of any state in the union Demographics are increasing the risk of natural hazards to Oregonians as development is increasingly being carried out on more hazardous land than in the past With proper information it is possible to manage the risks posed by these geologic hazards Among other information the appendices to this manual summarize the geologic hazards of Oregon provide perspectives on how the geologic view of the hazard may differ from the In spite of efforts to manage risks some actions are ineffective at reducing damage from geologic hazards There are many reasons including The hazards are unrecognized or poorly understood The full range of choices for risk reduction is not fully appreciated The issue is so diverse and involves so many participants that the process simply bogs down and dies out The community chooses to handle the hazard on a caseby case basis rather than develop a comprehensive strategy Legal jeopardy may not be well understood It is common for those who find themselves dealing with hazards to enter into the arena with The effects of flooding do not end when the water recedes Cleanup and rebuilding may take months in some cases structures properties or even neighborhoods must be abandoned Lack of understanding of all the Flood control measures must be carefully planned so they do hazards they need to consider not cause more problems downstream
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