2020-2025 King County Regional Hazard Mitigation Plan Table of Contents Executive Summary................................................................................................................................................... 8 Introduction ............................................................................................................................................................. 10 Mitigation Plan Priorities: .................................................................................................................................. 10 Timeline ................................................................................................................................................................ 11 Revisions from 2015 Edition ............................................................................................................................ 11 Regional Hazard Mitigation Plan Chapters ..................................................................................................... 11 Hazard Mitigation Planning Process .................................................................................................................... 13 Mitigation Planning Partner Engagement ....................................................................................................... 15 Jurisdiction Plan Annex Process ....................................................................................................................... 16 Review and Incorporation of Reports and Studies ........................................................................................ 16 King County Plan Update Timeline ................................................................................................................. 17 Support for Community Rating System (CRS) Communities ..................................................................... 20 Public Outreach Process .................................................................................................................................... 21 Continued Public Participation ......................................................................................................................... 26 King County Regional Hazard Mitigation Program Capabilities ..................................................................... 27 Plan Integration ................................................................................................................................................... 27 Program and Policy Capabilities ....................................................................................................................... 31 Integration with Departments and other Jurisdictions ................................................................................. 35 Potential Sources of Hazard Mitigation Funding .......................................................................................... 37 King County Hazard Mitigation Grant Assistance Program ....................................................................... 41 Participation in the National Flood Insurance Program ............................................................................... 41 Participation in CRS ........................................................................................................................................... 42 Regional Risk and Probability Summaries....................................................................................................... 43 Risk Assessment Overview .................................................................................................................................... 45 1 Methodology ........................................................................................................................................................ 46 Data ....................................................................................................................................................................... 46 Vulnerable Populations and Population-Based Vulnerability ...................................................................... 49 Determinants of Population Vulnerability........................................................................................................... 49 Jurisdiction-Specific Risk Assessments ............................................................................................................ 52 King County Development Trends and Risk Trajectory .............................................................................. 53 Regional Risk Profile: Avalanche .......................................................................................................................... 56 Hazard Description ............................................................................................................................................ 56 Vulnerability Characteristics and Previous Occurrences .............................................................................. 57 Scenario Drivers .................................................................................................................................................. 59 Priority Vulnerabilities ........................................................................................................................................ 59 Priority Impact Areas ......................................................................................................................................... 59 Regional Risk Profile: Civil Disorder ................................................................................................................... 62 Hazard Description ............................................................................................................................................ 62 Vulnerability Characteristics and Previous Occurrences .............................................................................. 63 Scenario Drivers .................................................................................................................................................. 64 Priority Vulnerabilities ........................................................................................................................................ 65 Priority Impact Areas ......................................................................................................................................... 66 Regional Risk Profile: Cyber Incident .................................................................................................................. 68 Hazard Description ............................................................................................................................................ 68 Vulnerability Characteristics and Previous Occurrences .............................................................................. 70 Scenario Drivers .................................................................................................................................................. 72 Priority Vulnerabilities ........................................................................................................................................ 75 Priority Impact Areas ......................................................................................................................................... 75 Regional Risk Profile: Dam Failure ...................................................................................................................... 78 2 Hazard Description ............................................................................................................................................ 78 Vulnerability Characteristics and Previous Occurrences .............................................................................. 82 Scenario Drivers .................................................................................................................................................. 83 Priority Vulnerabilities ........................................................................................................................................ 85 Priority Impact Areas ......................................................................................................................................... 86 Full List of Dams That Impact King County ................................................................................................. 90 Regional Risk Profile: Earthquake ...................................................................................................................... 101 Hazard Description .......................................................................................................................................... 101 Vulnerability Characteristics and Previous Occurrences ............................................................................ 101 Scenario Drivers ................................................................................................................................................ 104 Priority Vulnerabilities ...................................................................................................................................... 106 Priority Impact Areas ....................................................................................................................................... 108 Regional Risk Profile: Flood 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