Multi-Hazard Risk Identification and Assessment
"A Cornerstone of the National Mitigation Strategy

Assessment Prepared in support of the International Decade for Natural Disaster Reduction

A MESSAGE FROM THE DIRECTOR
Photo of James Lee Witt

During a presentation before the U.S. Congress in 1993, I indicated that the United States cannot afford the continuing 
high costs of natural and technological disasters. We cannot afford the economic costs to the American taxpayer, nor can we afford the social costs inflicted on our communities and citizens. 

The Federal Emergency Management Agency (FEMA) has embarked on a full-scale effort to help build safer communities. Our goals include increasing public awareness of hazards and loss reduction (mitigation) measures, reducing the risk of loss of life and property, and protecting our nations communities and the economy from all types of natural and technological hazards. 

FEMA's role in this effort is to provide leadership and programmatic, technical, and financial support to our partners: Federal, State, and local agencies; national and State legislative bodies; colleges and universities; private-sector organizations; volunteer organizations; and individuals. Our partnerships are accomplished through a comprehensive, risk-based, all-hazards program of mitigation, preparedness, response, and recovery. 

FEMA has been busy. In addition to responding to numerous disasters, we have made significant progress in developing mitigation programs. Among many accomplishments, in 1995 we developed a national strategy for mitigation after meeting with our partners across the United States. We have started a process that is vital to successful implementation of pre- and post-
disaster mitigation. We have also executed performance-based partnership agreements with all 50 States and the U.S. territories. 

An integral part of implementing our mitigation strategy is the transfer and sharing of information and knowledge. Multi-Hazard Identification and Risk Assessment supports that objective. We look forward to working with our partners to update and expand scientific knowledge and applied technology so that we will be better prepared for the hazards that will affect our families, friends and neighbors in the future. 

Signature of James Lee Witt, Director 
Federal Emergency Management Agency 


A MESSAGE FROM THE ASSOCIATE DIRECTOR FOR MITIGATION
Photo of Michael Armstrong

Hurricanes, earthquakes, wildfires, and tornadoes cause millions of dollars in damage. They force individuals and families out of their homes and destroy their belongings. Businesses often lose money or even close their doors for good. Public infrastructure such as roads, bridges, water supplies and sewage systems suffer damage, diminishing our quality of life. These losses tear at the very fabric of our communities and our lives. 

What is most saddening is that much of the suffering and losses associated with natural disasters is unnecessary. While we cannot keep natural hazards from occurring, we do know how to reduce their effects. By taking actions in our homes, businesses, and our communities to mitigate risks, we can reduce disaster impacts and break the cycle of losses that we have witnessed in recent years. In a nutshell, we can reduce our nations vulnerability to natural disasters. Central to our success in breaking the disaster-loss cycle is our ability to identify the hazards that we face and to assess the level of risk they bring to our lives.
 
The report before you is a product of FEMA's efforts to further develop such a capability at the national level. It 
documents months of research and coordination and provides a baseline of knowledge concerning the identification 
of hazards and assessment of the risks. The report was created to be a working or living reference document for State and local specialists. As such, it is FEMAs intention to periodically update or amend the report to ensure that the best and most accurate information is available to those who need it most. 

I believe this report provides State and local decision-makers with a better understanding of the types and magnitudes of the natural and technological hazards which their communities face. This, in turn, will help them evaluate exposure of people and property and assess the consequences of hazard events. With these tools, we can make more informed decisions about reducing future disaster losses. I trust you will find this report useful and informative. We look forward to working together to address natural and technological hazards nationwide. 

Signature of Michael Armstrong 
Associate Director for Mitigation 


ACKNOWLEDGEMENTS
This report was prepared by the Federal Emergency Management Agencys (FEMA) Mitigation Directorate, with assistance from 
Michael Baker Jr., Inc., Arthur D. Little, Inc., of Cambridge, MA, and Mr. John Hilson of Boulder, CO. We wish to acknowledge the valuable contributions of these organizations, the staffs of the FEMA Regional Offices, and the following organizations and individuals: 

Atmospheric 
 Arthur Mears, Inc., Gunnison, CO 
 Carbon Dioxide Information Analysis Center, World Data Center for Atmospheric Trace Gasses, Oak Ridge National Laboratory, Oak Ridge,TN 
 Mr. Chris Jones, Earth Tech, Charlottesville, VA 
 Mr. Knox Williams, Colorado Avalanche Information Center, Denver, CO 
 EOSDIS Distributed Active Archive Center, User Services Office, National Aeronautic and Space Administration, Oak Ridge,TN 
 National Climatic Data Center, National Oceanic and Atmospheric Administration, Asheville, NC 
 National Hurricane Center, National Weather Service, Coral Gables, FL 
 National Weather Service, National Oceanic and Atmospheric Administration, Silver Spring, MD Geologic 
 Geologic Division, U.S. Geological Survey: Reston, VA; Golden, CO; Menlo Park, CA; Seattle, WA 
 Geology Department, University of Washington, Seattle, WA Photo: Red Cross 
 J.H. Wiggins Company, Redondo Beach, CA 
 National Landslide Information Center, U.S. Geological Survey, Golden, CO 
 Oklahoma State University, Stillwater, OK 
 Slosson and Associates, Van Nuys, CA 
 Water Resources Division, U.S. Geological Survey: Sacramento, CA; Tucson, AZ 


Hydrologic 
 Institute for Water Resources, U.S. Army Corps of Engineers, Fort Belvoir, VA 
 Property Loss Research Bureau, Schaumberg, IA 
 TEMCO/Department of Public Safety, Pago Pago, American Samoa 
 U.S. Army Corps of Engineers, Headquarters, Division, and District Offices 
 University of California, Santa Cruz, CA 
 Dr. Robert Dolan, University of Virginia, Charlottesville, VA 


Seismic 
 Building Seismic Safety Council, Washington, DC 
 Geologic Division, U.S. Geological Survey: Golden, CO; Reston, VA; Seattle, WA 
 National Earthquake Information Center, U.S. Geological Survey, Golden, CO 
 National Geophysical Data Center, National Oceanic and Atmospheric Administration, Boulder, CO 
 National Institute of Building Sciences, Washington, DC 
 Dr. Edward Bernard, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA 


Volcanic 
 Cascades Volcano Observatory, U.S. Geological Survey, Vancouver, WA 
 Geologic Division, U.S. Geological Survey, Menlo Park, CA 


Wildfire 
 Arapaho/Roosevelt National Forest, U.S. Forest Service, Fort Collins, CO 
 Boulder County Land Use Department, Boulder, CO 
 Colorado State Forest Service, Fort Collins, CO 
 Fire and Aviation, U.S. Forest Service, Washington, DC 
 Intermountain Fire Sciences Lab, Missoula, MT 
 National Interagency Fire Center, Boise, ID 
 State and Private Forestry, Region 2, U.S. Forest Service, Denver, CO 


Technological 
 Mr. Martin McCann, Jr., Center on the Performance of Dams, Stanford University, Stanford, CA 
 Risk Management Solutions, Inc., Menlo Park, CA 

 
Multiple Hazards 
 Department of Geology and Geography, Hunter College of the City University of New York, New York, NY 
 Disaster Preparedness Resources Centre, University of British Columbia, Vancouver, British Columbia 
 Insurance Institute for Property Loss Reduction, Boston, MA 
 Board of Natural Disasters, National Research Council, Washington, DC 
 National Fire Protection Association, Quincy, MA 
 Ms. Mary Fran Myers, Natural Hazards Research and Applications Center, Institute of Behavioral Sciences, University of Colorado, Boulder, CO 


Risk Assessment 
 Mr. Hemant Shah and Dr. Scott Lawson, Risk Management Solutions, Inc., Menlo Park, CA 


TABLE OF CONTENTS

Message from the Director 
Message from the Executive Associate Director for Mitigation 
Acknowledgments 
List of Illustrations 
Executive Summary 
Introduction
 
Part INatural Hazards 
Subpart A Atmospheric Hazards
	Chapter 1 Tropical Cyclones
	Chapter 2 Thunderstorms and Lightning
	Chapter 3 Tornadoes 	Chapter 4 Windstorms
	Chapter 5 Hailstorms
	Chapter 6 Snow Avalanches 
	Chapter 7 Severe Winterstorms
	Chapter 8 Extreme Summer Weather 

Subpart B Geologic Hazards
	Chapter 9 Landslides 
	Chapter 10 Land Subsidence
	Chapter 11 Expansive Soils
	
Subpart C Hydrologic Hazards 
	Chapter 12 Floods 
	Chapter 13 Storm Surges
	Chapter 14 Coastal Erosion
	Chapter 15 Droughts 
Subpart D Seismic Hazards
	Chapter 16 Earthquakes
	Chapter 17 Tsunami Events

Subpart E Other Natural Hazards
	Chapter 18 Volcanic Hazards 
	Chapter 19 Wildfire Hazards

Part IITechnological Hazards 
	Chapter 20 Dam Failures
	Chapter 21 Fires
	Chapter 22 Hazardous Materials Events 
	Chapter 23 Nuclear Accidents

Part IIIRisk Assessment Approaches

	Chapter 24 HAZUS: Standardized Risk Assessment (Loss Estimation) Methodology
	Chapter 25 Other Risk Assessment Approaches 

Part IVActivities Under the National Mitigation Strategy

	Chapter 26 Hazard Identification and Risk Assessment
	Chapter 27 Applied Research and Technology Transfer
	Chapter 28 Public Awareness, Training, and Education 
	Chapter 29 Incentives and Resources
	Chapter 30 Leadership and Coordination 

Part VSummary and Conclusions 
	Chapter 31 Summary and Conclusions 
Appendix A Acronyms and Abbreviations
Appendix B Metric Conversion Table

LIST OF ILLUSTRATIONS

Tables Page 
Table 1-1 Classification Criteria for Tropical, Subtropical, and Extratropical Cyclones
Table 1-2 Saffir/Simpson Hurricane Scale Ranges 
Table 1-3 Most Intense U.S. Hurricanes at Time of Landfall: 19001994
Table 1-4 Two-Day Precipitation Totals, Eastern North Pacific Tropical Cyclones: 19001984
Table 1-5 Deadliest U.S. Hurricanes: 19001994 
Table 1-6 Costliest U.S. Hurricanes: 19001994
Table 1-7 Significant Hawaiian Hurricanes of the 20th Century 
Table 3-1 Fujita Tornado Scale 
Table 3-2 Ten Most Deadly Tornado Events: 18701979 
Table 3-3 Six Most Deadly Recent Tornado Events: 1980-1994
Table 6-1 Vegetation as an Avalanche-Frequency Indicator 
Table 6-2 Avalanche Impact Pressures Related to Damage
Table 7-1 Superstorm of March 1993: Deaths, Injuries, and Damages by State
Table 8-1 Heat Index / Heat Disorders 
Table 10-1 Estimated Annual Damage From Land Subsidence
Table 11-1 Estimated Annual Soil-related Damage Costs
Table 13-1 Factors Influencing the Severity of Coastal Storms 
Table 13-2 Dolan/Davis Nor'easter Scale 
Table 14-1 Summary of Natural Factors Affecting Shoreline Change 
Table 14-2 Estimated Extent of Eroding Shorelines: 1971 
Table 16-1 Earthquake Felt Intensity: The Modified Mercalli Intensity Scale
Table 16-2 Relationship Between Modified Mercalli Intensity Scale and Seismic Magnitude
Table 16-3 Significant U.S. Earthquakes: 1964-1994 
Table 18-1 Selected Active and Potentially Active U.S. Volcanoes 
Table 18-2 Lava Flow Hazard Zones for the Island of Hawaii 
Table 20-1 Selected Dam Failures in the United States: 1874-1995 
Table 21-1 Fires in the Northeast Region Reported by U.S. Public Fire Departments by Type of Natural Condition: 1984-1993 Annual Average
Table 21-2 Fires in the North Central Region Reported by U.S. Public Fire Departments by Type of Natural Condition: 1984-1993 Annual Average
Table 21-3 Fires in the Southern Region Reported by U.S. Public Fire Departments by Type of Natural Condition: 1984-1993 Annual Average
Table 21-4 Fires in the Western Region Reported by U.S. Public Fire Departments by Type of Natural Condition: 1984-1993 Annual Average
Table 25-1 Variables, Units of Measure, and Summary Statistics for Exposure Variables for 3,140 U.S. Counties 


Figures Page 
Figure i-1 Geography of Natural Hazards 
Figure i-2 Total Insured Losses for Major Natural Disasters: 19891995
Figure 1-1 Total Number of U.S. Hurricanes per month: 19001994 
Figure 1-2 U.S. Hurricane Landfalls (Categories 15): 1900-1994 
Figure 1-3 Value of Insured Coastal Property Exposures By Mainland State: 1993
Figure 12-1 An Example of a Digital Flood Insurance Rate Map, El Paso County, CO 
Figure 14-1 Schematic Diagram of Storm Wave Attack on Beach and Dune 
Figure 15-1 Accumulative Departure of Monthly Stream Discharge From Long-Term Mean Monthly Streamflow at a Hypothetical Stream Gaging Station
Figure 16-1 Wave Fronts: Directions of Vibration
Figure 16-2 Surface Faulting 
Figure 16-3 Probabilistic Maximum Ground Acceleration in the Conterminous United States
Figure 18-1 Volcanoes of the Aleutian Arc 
Figure 19-1 Live Fuel Moisture - Departure from Average Greenness 
Figure 19-2 Sample of a Fire Danger Rating Map 
Figure 19-3 Boulder County Wildfire Hazard Pilot Map 
Figure 24-1 Modules of HAZUS 
Figure 25-1 A Risk Matrix Approach 
Figure 25-2 Example of Risk Matrix


Maps Page 
Map i-1 Presidential Disaster Declarations by State for the Period of 1975-1995
Map 1-1 Total Number of Direct and Indirect Impacts From Landfalling Hurricanes for Coastal Counties From Texas to Maine: 1900-1994 
Map 1-2 Coastal Counties From Texas to Maine and the 5% Chance Associated with the Occurrence of Landfalling Hurricane Magnitude (by Category) Being Equaled or Exceeded in Any Given Year Map 2-1 Thunderstorm Hazard Severity Based on the Annual Average Duration of Thunder Events: 1948-1977 
Map 2-2 Thunderstorm Hazard Severity Based on the Annual Average Number of Thunder Events:1948-1977 
Map 2-3 Areal Extent and Severity of Lightning Hazard Based on the Mean Annual Lightning Strike Density: 1948-1977
Map 2-4 Total Deaths Caused by Lightning: 1959-1993 
Map 3-1 Average Annual Number of Tornadoes Per State: 1953-1993 
Map 3-2 Geographic Distribution of Tornadoes Based on Total Number of Tornado Events Per One Degree of Latitude and Longitude: 1954-1993 
Map 3-3 Average Annual Deaths by State Caused by Tornadoes: 1953-1993
Map 4-1 Wind Climatology for Special High Wind Regions and 50-Year Return Period Fastest Mile Speeds 
Map 5-1 Annual Frequency of Hailstorms in the United States 
Map 6-1 Qualitative Indicator of the Severity of Snow Avalanches in the United States
Map 7-1 Snowdepth (in Centimeters) With a 5% Chance of Being Equaled or Exceeded in Any Given Year, From Solar and Meteorological Surface Observation Network: 1961-1990
Map 8-1 Heat Index with a 5% Chance of Being Exceeded in Any Given Year
Map 9-1 Landslide Potential Based on Adverse Formations Associated with Past Landslide Activity
Map 9-2 Landslide Incidence and Susceptibility in the Conterminous United States
Map 10-1 Cumulative Subsidence Damage Caused by Mining
Map 10-2 Cumulative Subsidence Damage Caused by Sinkholes
Map 10-3 Cumulative Subsidence Damage Caused by Underground Fluid Withdrawal 
Map 10-4 Cumulative Subsidence Damage Caused by Hydrocompaction 
Map 10-5 Cumulative Subsidence Damage Caused by Drainage of Organic Soils
Map 11-1 Clay Swelling Potential 128
Map 12-1 Geographic Distribution by County of Households in the United States in the 1-Percent-Annual-Chance Floodplain 
Map 13-1 Expected Storm Surge Elevations with a 10-Year Recurrence Interval 
Map 14-1 Average Annual Shoreline Change Rates for the Western United States
Map 14-2 Average Annual Shoreline Change Rates for the Great Lakes and Eastern United States
Map 15-1 Spatial Variation in the July-to-January Mean Flow With a 5-Percent Chance of Not Being Exceeded in Any Given Year
Map 15-2 Status of Drought Planning in the United States 
Map 16-1 Spatial Variation in the Effective Peak Acceleration Coefficient (Aa) By County 
Map 16-2 Spatial Variation in the Effective Peak Velocity Coefficient (Av) By County 
Map 17-1 Tsunami Elevations With a 90-Percent Chance of Not Being Exceeded in 50 Years
Map 18-1 Areas Subject To Lava Flows and Ashfall in the Western United States
Map 20-1 Dams Included in the National Inventory of Dams
Map 20-2 Dams in the National Inventory of Dams Classified as Having High or Significant Hazard
Map 22-1 Superfund Sites in the United States as of 1993 
Map 23-1 Nuclear Powerplants in the United States as of 1993 
EXECUTIVE SUMMARY
Experience is a good teacher, but changes in population patterns, physical characteristics of structures, and economic development during the past century suggest that relying on experiences alone is inadequate for judging vulnerability. 

From Reducing Disasters Toll: 
The United States Decade for 
Natural Disaster Reduction 

 
EXECUTIVE SUMMARY
For decades, most Americans assumed that they were immune to, or could control, the forces and fury of natural hazards. With each new flood, hurricane, tornado, earthquake, avalanche, landslide, or wildfire, that assumption has proven incorrect. Since 1990, the United States has experienced numerous major disasters,among them were Hurricanes Andrew, Iniki, Marilyn and Opal; the Great Midwest Flood of 1993; the Northridge Earthquake; and wildfires in California. 

Recent disasters, regardless of scale, have focused the attention of government officials and citizens alike on 
the economic, human, and environmental costs. With each new event, it becomes more apparent that a unified, concerted approach to lessening if not eliminating the risks is needed. The United States has the technical skill to reduce loss of life and property. Unfortunately, until recently, the will to do so has been unfocused. 

Under the leadership of Director James Lee Witt, the staff of the Federal Emergency Management Agency (FEMA) has developed a national approach to mitigating human and economic loss caused by disasters. As one part of the effort, FEMA initiated a research project to clarify and document previous efforts to identify natural and technological hazards, and to assess associated risks. This report, Multi-Hazard Identification and Risk Assessment, is prepared as a reference document to summarize the findings.
 
For specific natural and technological hazards, the report summarizes the state of scientific and technical knowledge on identification and the risks that have been or can be assigned to each hazard. FEMA's recently developed risk assessment methodology, Hazards United States, known as HAZUS, is introduced.
 
Also summarized are the National Mitigation Strategy and highlights from recent successes in each of the five major elements of the Strategy: (1) hazard identification and risk assessment; (2) applied research and technology transfer; (3) public awareness, training, and education; (4) incentives and resources; and (5) leadership and coordination.
 
Using Geographic Information System technology and available data, selected maps were generated. Often, the maps illustrate areas that appear to be most susceptible to individual and multiple hazards. Some readers may be surprised at the variety and extent of hazards that may occur in various regions of the United States.
 
The maps do not, and are not intended to, depict a final assessment of where hazards exist or where disasters are likely to occur. Uncertainty about risks will always be present, but assessments can be improved. 

Brief summaries of existing programs and initiatives, and plans for future mitigation activities, suggest that while a great deal has been accomplished, much more remains to be done. 

Multi-Hazard Identification and Risk Assessment is a reference that is available to assist hazard identification, risk assessment, and mitigation specialists in refining our understanding of hazards and their impacts on people and the built environment. FEMA intends to update this report as identification, assessment, and mitigation approaches are refined. 

INTRODUCTION 
Want of foresight, unwillingness to act when action would be simple and 
effective, lack of clear thinking, confusion of counsel until the emergency 
comes, until self-preservation strikes its jarring gong - these are the 
features which constituted the endless repetition of history. 

Winston Churchill
Speaking to the House of Commons 
Before World War II


INTRODUCTION BACKGROUND 
Since its creation in 1979, the role of the Federal Emergency Management Agency (FEMA) has been to develop, implement, and support policies and programs for emergency management at the national, State, and local levels. Such policies and programs are necessary because periodically throughout its history the United States has been damaged disastrously by natural and 
technological hazard events. Many events, even if not disastrous in scope or magnitude, take their toll in terms of life and property. Cumulatively, natural and technological hazard events cost millions each year and affect every State (Figure i-1). 

Presidential disaster declarations throughout the United 
States and its territories from 1975 through 1995 are 
shown on Map i-1. 

During the late 1980s and early 1990s, the United States experienced unprecedented devastation from major events, such as earthquakes, hurricanes, tropical storms, floods, landslides, volcanic eruptions, severe winterstorms, and wildfires. Over 500 people lost their lives during these events. Between 1989 and 1994, 291 presidential disaster declarations were issued. Federal disaster assistance made available to affected States, communities, and individuals cost the U.S. Treasury over $34 billion. Figure i-2 presents information provided by the Insurance Research Council and the Property Claims Service, Inc., on insured losses for selected major natural disasters that occurred from 1989 to 1995. 

Under the leadership of Director James Lee Witt, FEMA's efforts have been redefined and better focused. FEMA's primary mission is to reduce the risk of loss of life and property in the United States, and to protect U.S. institutions from the disastrous effects of natural and technological hazards. FEMA accomplishes this mission by leading, coordinating with, and supporting specialists at every level of government (Federal, State, and local) and the private sector in the development of a comprehensive, risk-based emergency management program of mitigation, preparedness, response, and recovery. 

The importance and necessity of FEMA's efforts are underscored by the following statistics: 

 Estimates indicate approximately 9 to 11 million homes are at risk from flooding, approximately 25 million homes are at risk from severe wind hazards, approximately 2 million homes may be at risk from coastal storm surge, and at least 50 million homes may be located in counties with significant earth-quake risk;

 More than 36 million people live in the most hurricane-prone counties from Maine to Texas, and the number is expected to grow to 73 million by the year 2010; and 

 During the last 5 years alone, combined Federal disaster assistance and insurance industry payments totaled over $67 billion. 

Presidents and the U.S. Congress have exhibited strong leadership in raising awareness concerning the United States' exposure to hazard events. They have provided valuable input to FEMA in the development of its policies and programs. Recently, the U.S. Congress stressed the importance of identifying natural and technological hazards and assessing the risks posed to people and property. 

In Senate Report 101-128, which accompanied the 1990 FEMA appropriations bill, the Senate Appropriations Committee directed FEMA to ". . . prepare a study on the principal threats facing communities and local emergency management coordinators . . . The study should rank the principal threats to the population according to region and any other factors deemed appropriate." 

From 1990 to 1993, FEMA produced reports that summarized the principal natural and technological threats, or hazards, facing communities and emergency management coordinators. However, the limitations of these rankings were acknowledged in the first report, dated April 1990. Some of the limiting factors cited were the wide variation in application of criteria to the same hazards, differences between the State and regional impacts of particular hazards, applicability of threats from region to region, and variances in amounts and types of data collected on particular hazards. 

The April 1990 report cited the following as factors that make relative rankings of hazards, even within regions, very difficult: level of community preparedness; degree to which urban or sparsely populated rural areas are affected by disaster events; and emergency managers' perceptions regarding the potential severity, magnitude, or rankings of particular hazards. 


U.S. Map Map i-1. Presidential disaster declarations by State for the period of 1975 - 1995. 
The Pacific Territories have had 35 declarations. 
Source: FEMA, 1995.
 
As a direct result of the disasters of the early 1990s, in particular the Midwest Floods of 1993, the U.S. 

Congress directed FEMA to place its highest priority on working with State and local agencies to mitigate the impacts of future natural hazard events. This marked a fundamental shift in policy: rather than placing primary emphasis on response and recovery, FEMA's focus broadened to incorporate mitigation as the foundation of emergency management.
 
NATIONAL MITIGATION STRATEGY AND GOAL 
In keeping with congressional directive, Director Witt and FEMA staff led the development of the National Mitigation Strategy. FEMA derived 10 fundamental principles for the framework and objectives of the National Mitigation Strategy. 

1. Risk reduction measures ensure long-term economic success for the community as a whole rather than short-term benefits for special interests. 
2. Risk reduction measures for one natural hazard must be compatible with risk reduction measures for other natural hazards. 
3. Risk reduction measures must be evaluated to achieve the best mix for a given location. 
4. Risk reduction measures for natural hazards must be compatible with risk reduction measures for technological hazards and vice versa. 
5. All mitigation is local. 
6. Disaster costs and the impacts of natural hazards can be reduced by emphasizing pro-active mitigation 
before emergency response; both pre-disaster (preventive) and post-disaster (corrective) mitigation is needed. 
7. Hazard identification and risk assessment are the cornerstones of mitigation. 
8. Building new Federal-State-local partnerships and public-private partnerships is the most effective means of implementing measures to reduce the impacts of natural hazards. 

INTRODUCTION 
GEOGRAPHY OF NATURAL HAZARDS 
Although occasional events of a particular natural hazard can occur in any area of the United States, most tend to occur more frequently in some areas than in others. The following table lists the hazards that are most prevalent in each area. 


FIGURE i-1. 
Source: Compiled by FEMA, 1995 

WEST
Avalanches 
Droughts 
Earthquakes 
Expansive Soils 
Extreme Heat 
Hailstorms 
Floods 
Landslides 
Land Subsidence 
Storm Surges 
Tsunamis 
Tornadoes 
Typhoons 
Volcanoes 
Wildfires 
Windstorms

MIDWEST
Droughts 
Earthquakes 
Expansive Soils 
Extreme Heat 
Floods
Hailstorms
Severe Winter Storms
Thunder & Lightning
Tornadoes
Windstorms 

SOUTH
Coastal Erosion 
Droughts 
Earthquakes 
Expansive Soil 
Extreme Heat 
Floods
Hurricanes
Land Subsidence
Storm Surges
Thunder & Lightning
Tornadoes
Windstorms
 
NORTHEAST
Coastal Erosion 
Earthquakes 
Extreme Heat 
Floods
Hurricanes
Landslides
Severe Winter Storms
Storm Surges


FIGURE i-2.Total insured losses for major natural disasters: 1989-1995. 
Source: From Property Claim Services, 1997; and Insurance Research Council, 1995 
* Only 2 of the 27 fires were officially classified by the insurance industry as catastrophes. 
Costs associated with other fires at the same time may have caused losses to reach $.95 billion. 

($ amounts in billions)
Hurricane Opal 10/95: $2.1
Hailstorm TX and NM 5/95:$1.135
Severe Winter Storm 1/94-2/94:$1.60
Northridge, CA Earthquake 1/94:$12.50
Southern CA Fires* 10/93-11/93:$.725
Midwest Floods 6/93-8/93:$.60
Severe Winter Storm 3/93:$1.75
Hurricane Iniki 9/92:$1.60
Hurricane Andrew 8/92:$15.50
Oakland, CA Fire 10/91:$1.70
Denver, CO Wind, Hail, Tornadoes 7/90:$.625
Loma Prieta, CA Earthquake 10/89:$.96
Hurricane Hugo 9/89:$4.20

 
9. Those who knowingly choose to assume greater risk must accept responsibility for that choice. 

10. Risk reduction measures for natural hazards must be compatible with the protection of natural and 
cultural resources.
 
Using these principles as guidance, FEMA established a National Mitigation Goal to be accomplished by the year 2010. The two components of the goal are (1) to substantially increase public awareness of natural hazard risk so that the public demands safer communities in which to live and work, and (2) to significantly reduce the risk of loss of life, injuries, economic costs, and destruction of natural and cultural resources that result from natural hazards. 

To meet the National Strategy Goal, FEMA set specific objectives for five major "elements" of the Strategy: 
 Hazard identification and risk assessment; 
 Applied research and technology transfer; 
 Public awareness, training, and education; 
 Incentives and resources; and 
 Leadership and coordination. 

INTENT OF THIS REPORT 
This report is intended to serve as a baseline for hazard identification and risk assessment efforts. The research 
and reviews documented in this report are not intended to be exhaustive evaluations of hazards and the risks they pose throughout the United States. The research, monitoring, mitigation measures, recommendations and federal programs described herein are current as of 1995. The report may be updated as hazard identification and risk assessment techniques are refined and improved, and as Federal, State, and local programs evolve. 

FEMA initiated this report to focus primarily on identification of hazards and factors important to risk assessment: 
probability and frequency, exposure, and consequences. 

FEMA also began development of a consistent methodology to assess risks posed by natural and technological hazards. 

The baseline of knowledge was developed by identifying and contacting Federal and State agencies, research institutes, and universities known to have leading experts in each specialty area. For example, experts from the National Oceanic and Atmospheric Administration were contacted regarding atmospheric hazards; experts from the U.S. Geological Survey were 
contacted regarding geologic, seismic, and volcanic hazards; and experts at the Natural Hazards Research and Applications Information Center at the University of Colorado were contacted for information on multiple hazards. 


KEY TERMS AND DEFINITIONS 
Terminology is important because variations in meaning lead to differences in hazard identification and measures 
of risk. The following key terms and definitions are used in this report: 

Hazard means an event or physical condition that has the potential to cause fatalities, injuries, property damage, infrastructure damage, agricultural loss, damage to the environment, interruption of business, or other types 
of harm or loss. 

Hazard Identification means the process of defining and describing a hazard, including its physical characteristics, 
magnitude and severity, probability and frequency, causative factors, and locations/areas affected. 

Risk means the potential losses associated with a hazard, defined in terms of expected probability and frequency, 
exposure, and consequences. 

Probability and Frequency means a measure of how often an event is likely to occur. Frequency can be expressed as the average time between occurrences or exceedances (non-exceedances) of an event or the percent chance or probability of the event occurring or being exceeded (not exceeded) in a given year or a longer time period. 

Exposure means the number, types, qualities, and monetary values of various types of property or infrastructure 
and life that may be subject to an undesirable or injurious hazard event. 

Consequences mean the damages (full or partial), injuries, and losses of life, property, environment, and business that can be quantified by some unit of measure, often in economic or financial terms. 

Risk Assessment means a process or method for evaluating risk associated with a specific hazard and defined in terms of probability and frequency of occurrence, magnitude and severity, exposure, and consequences. 

Mitigation means sustained action taken to reduce or eliminate long-term risk to people and property from hazards and their effects. Mitigation distinguishes actions that have a long-term impact from those that are more closely associated with preparedness for, immediate response to, and short-term recovery from a specific event. 

PREVIOUS HAZARD IDENTIFICATION AND RISK ASSESSMENT ACTIVITIES 
Over the past 12 years, FEMA and State emergency managers have developed a variety of tools to assist with hazard identification and risk assessment. Two such cooperative programsthe Integrated Emergency Management System (IEMS) and the Capability and Hazard Identification Program (CHIP)have evolved and have contributed significantly to hazard identification program activities.
 
FEMA instituted IEMS in 1983. Its objective was to develop and maintain a credible emergency management capability nationwide by integrating activities along functional lines at all levels of government and, to the fullest extent possible, across all hazards. Through a 13-step process, IEMS collected basic information from State and local emergency management organizations on which reasonable and justifiable plans could be made and implemented to increase emergency management capabilities nationwide. 

The 13 steps in the IEMS process were: (1) hazards analysis, (2) capability assessment, (3) emergency operations plan development, (4) capability maintenance, (5) mitigation efforts, (6) emergency operations, (7) emergency operations evaluation, (8) capability short-fall determination, (9) multi-year development plan development, (10) modification of multi-year development plan for annual increments, (11) estimate of State/local financial resource requirements, (12) estimate of Federal financial resource requirements, and (13) annual review of completed work. Based on the review completed in Step 13 each year, the process was begun again.
 
Under CHIP, instituted in 1989 to replace IEMS, FEMA established a national database of information on the status of emergency preparedness and the impact of FEMA funds on State and local government operations. Emergency management data were collected for 3,300 communities and maintained in a comprehensive and easily accessible database. However, a drawback of the "self-assessment" was the lack of consistent criteria for reporting, which resulted in incomplete and inaccurate information. 

Through regular updates of the CHIP database, local government officials provided information on natural hazards in their areas, including the likelihood and frequency of events and the impacts on local population and property. They also provide information on local emergency management expenditures, including totals expended and the sources of funding. By answering questions separated into five topic areas, local governments provided information to allow assessment of their capability to deal with disasters. The five topic areas are: planning, logistics, training and education, operations, and administration. 

On the Federal level, the information from CHIP was used to prepare reports to the U.S. Congress on the status of emergency management capabilities. It also was used to evaluate the effectiveness of FEMA programs in delivery of financial and technical assistance to State and local governments. At the local level, CHIP was used as a planning tool, guiding local jurisdictions through a logical sequence: identify hazards; assess capabilities to address those hazards; set priorities for improving those capabilities; and schedule process activities to improve those capabilities. 

REPORT CONTENT AND FORMAT 
Two categories of hazards are covered: natural hazards 
and technological hazards. Natural hazards, the largest 
single contributor to catastrophic or repetitive damage 
to communities nationwide, evolve from atmospheric 
or weather, geologic, hydrologic, and seismic events. 

They pose threats in all areas of the United States. 
The impacts of natural hazards can be local or wide-
spread, predictable or unpredictable. Resulting property 
and infrastructure damage can range from minor to 
major, depending on whether hazard events affect 
major or minor population centers. 

Technological or manmade hazards have expanded dramatically 
throughout the 20th century. Like natural 
hazards, their effects can be local or widespread. They 
are frequently unpredictable and have the potential to 
cause substantial loss of life in addition to property 
damage. Some technological hazards can be significant 
threats to infrastructure. For the purposes of this report, 
the discussions of technological hazards are limited to 
those that have been or may be triggered by natural 
events. 
To present what is known today with respect to hazard 
identification and risk assessment, this report is organized 
to allow location of information on a specific hazard 
or a group of hazards. It is intended as a reference 
document for use by emergency management and miti-

xxvii INTRODUCTION 
gation specialists in all levels of government and the 
private sector. 
For each hazard, the chief characteristics necessary for 
hazard identification are described, followed by the factors 
required in risk assessment: probability and frequency, 
exposure, and consequences. Each chapter 
includes brief summaries on previous and on-going 
research, data collection and monitoring activities, and 
brief discussions of mitigation measures and recommendations. 
The report is divided into five major parts: 
 Part I "Natural Hazards" presents atmospheric, geologic, 
hydrologic, seismic, and other hazards. 
Subpart A includes chapters on atmospheric hazards: 
tropical cyclones, thunderstorms and lightning, 
tornadoes, windstorms, hailstorms, snow avalanches, 
severe winterstorms, and extreme summer weather. 
Subpart B includes chapters on geologic hazards: 
landslides, land subsidence, and expansive soils. 
Subpart C includes chapters on hydrologic hazards: 
floods, storm surges, coastal erosion, and droughts. 
Subpart D includes chapters on seismic hazards: 
earthquakes and tsunami events. 
Subpart E includes chapters on two other natural 
hazards: volcanoes and wildfires. 
 Part II "Technological Hazards" presents dam failures, 
fires, hazardous materials events, and nuclear 
accidents. 
 Part III "Risk Assessment Approaches" presents risk 
assessment methodologies. One chapter addresses a 
method developed by the National Institute of 
Building Sciences, in cooperation with FEMA. The 
initial methodology estimates potential losses from 
earthquake events, but will be modified for other hazards. 
When completed, FEMA will make it available 
to State and local agencies along with many inventory 
databases. Components of other risk assessment 
methodologies are discussed briefly in a separate 
chapter. 
 Part IV "Activities Under the National Mitigation 
Strategy," summarizes the major elements of the 
National Mitigation Strategy and provides information 
on existing programs, recently completed activities, 
and future initiatives of FEMA, other Federal 
agencies, State and local agencies, and others. 
 Part V "Summary and Conclusions" presents an 
overall summary of the report and some general conclusions 
drawn from the research. 
To illustrate graphically the breadth and extent of both 
natural and technological hazards, color maps produced 
using Geographic Information System technology are 
included in Parts I and II. The source of data used to 
prepare each map is cited below the map caption for 
ready reference. A notation is made if information is 
not available for a particular State, territory, or region. 
STATE AND LOCAL PARTICIPATION IN 
REPORT UPDATE PROCESS 
Consistent definitions for, and a comprehensive identification 
of, natural and technological hazards can best 
be achieved through Federal-State-local partnerships 
and through cooperative efforts with private sector 
organizations, research and academic institutions, and 
individuals. The information in this report is intended 
to provide a baseline of knowledge. 
Future research on methodology, identification, assessment, 
and application will prove to be invaluable as 
risk-based strategies are refined. This report is a living 
document, and all Federal and State agencies, the scientific 
community, local government officials, emergency 
management specialists, and informed and concerned 
private sector organizations and individuals are 
encouraged to contribute to its enhancement and expansion 
in the coming years. 
To assist in the effort, comments may be submitted to: 
Multi-Hazard Identification and Risk Assessment 
Risk Assessment Branch 
Mitigation Directorate 
Federal Emergency Management Agency 
500 C Street SW 
Washington, DC 20472 
E-mail: anne.flowers@fema.gov 

All rights reserved
First edition published 1997
Printed in the United States of America
Includes bibliographical references and index