DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

OPEN-FILE REPORT 00-450

2000

National Landslide Hazards 

Mitigation Strategy

A FRAMEWORK FOR LOSS REDUCTION

U.S. GEOLOGICAL SURVEY 
ii
iii

DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

National Landslide Hazards 

Mitigation Strategy

A FRAMEWORK FOR LOSS REDUCTION

BY ELLIOTT C. SPIKER1 AND PAULA L. GORI1

OPEN-FILE REPORT 00-450

2000

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey 

editorial standards (or with the North American Stratigraphic Code). Any use of trade, products, or 

firm names is for descriptive purposes only and does not imply endorsement by the U.S. 

Government. 

1 USGS, National Center, Reston, VA 22092
iv

Preface

In fulfillment of the requirements of Public Law 106-113, the United States Geological Survey 

(USGS) submits this report, which describes a national strategy to reduce losses from landslides. 

This report includes a summary of the Nation’s needs for research, monitoring, mapping, and 

assessment of landslide hazards nationwide. 

House Report 106-222 accompanying the Interior Appropriations Bill for FY 2000, which was 

incorporated in Public Law 106-113, states: “The committee is concerned over the lack of 

attention given to the Survey’s landslide program. Because of this concern, the Survey is 

directed to develop by September 15, 2000, a comprehensive strategy, including the estimated 

costs associated with addressing the widespread landslide hazards facing the Nation. The 

preparation of this strategy should include the involvement of all parties having responsibility 

for dealing with the problems associated with landslides.”

Acknowledgments

This report was written by Elliott Spiker and Paula Gori of the USGS, based on an early draft by 

Randall Updike of the USGS and on the ideas and suggestions from landslide hazard experts 

and others who attended five stakeholder meetings. This report benefited from contributions 

and reviews from numerous USGS scientists and other Federal and State agency representatives. 

The authors would especially like to thank the American Association of State Geologists for 

their thoughtful input and review of the report.

Cover Photo: A landslide near McClure Pass, Colorado, in 1994 - This area of the Rocky 

Mountains has chronic problems where roads cross landslide areas. This car plunged into the 

landslide in the middle of the night, soon after the landslide occurred. Fortunately, no one was 

injured. Photograph by Terry Taylor, Colorado State Patrol.

September 2000
v

National Landslide Hazards Mitigation Strategy

A Framework for Loss Reduction

Table of Contents

Executive Summary vi

1. Introduction 1

1.1. Losses from Landslide Hazards in the United States 5

1.2. A National Strategy 7

2. The National Landslide Hazard Mitigation Strategy 9

2.1. Major Elements and Strategic Objectives 11

3. Action Items for National Strategy 23

3.1. Key Steps for Implementation 23

3.2. Management Plan 24

3.3. New and Enhanced Roles and Partnerships 24

Table 1. New Roles and Partnership Opportunities 25

3.4. Funding for National Strategy 27

3.5. Major Accomplishments and Products 30

Appendix A. Meetings with Stakeholders 31

Appendix B. Previous Reports and Sources of Information 34

Appendix C. Landslide Hazards and Other Ground Failures 35

Appendix D. Landslide Hazards Mitigation Strategies 38

Appendix E. Landslide Hazards Maps and Risk Assessments 40

Appendix F. Federal, State, and Local Agencies and Programs 42
vi

National Landslide Hazards Mitigation Strategy

A Framework for Loss Reduction

--------------------------------------------------------------

“Science by itself will not protect us. Federal, State and local governments, the private sector, 

volunteer and charitable organizations and individual citizens must work together in applying the 

science to make our communities safer.” 

Charles Groat, Director of the U.S. Geological Survey

--------------------------------------------------------------

Executive Summary

In response to the rising costs from landslide hazards in the United States, this report 

outlines key elements of a comprehensive and effective national strategy for reducing losses 

from landslides nationwide, including activities at the national, State, and local levels, in 

both the public and private sectors. It provides an assessment of the status, needs, and 

associated costs of this national landslide hazards mitigation strategy and is submitted in 

compliance with a directive of Public Law 106-113 (see Preface). The USGS derives its 

leadership role in landslide hazard related work from the Disaster Relief Act of 1974 

(Stafford Act). The Director of the USGS has been delegated the responsibility to issue 

disaster warnings for an earthquake, volcanic eruption, landslide, or other geologic 

catastrophe consistent with the 1974 Disaster Relief Act 42 U.S.C. 5201 et seq.

The strategy outlined in this report gives the Federal government a prominent role in leading 

efforts to reduce losses due to landslide hazards in partnership with State and local 

governments. The U.S. Geological Survey (USGS) has taken the lead in preparing this 

strategy on behalf of the large multi-sector, multi-agency stakeholder group involved in 

landslide hazards mitigation. A broad spectrum of expert opinion was sought in developing 

this strategy report as requested by the Congress in House Report 106-222.

This report outlines the essential elements of a National Landslide Hazards Mitigation 

Strategy that when implemented would reduce the cost of landslide hazards. It includes 

developing new partnerships between government at all levels, academia, and the private 

sector, and expanding landslide research, mapping, assessment, real-time monitoring, 

forecasting, information management and dissemination, development of mitigation tools, 

and emergency preparedness and response. Such a strategy makes use of new technological 

advances, enlists the expertise associated with other related hazards such as floods, 
vii

earthquakes and volcanic activity, and utilizes incentives for the adoption of loss reduction 

measures nationwide. 

The strategy envisions a society that is fully aware of landslide hazards and routinely takes 

action to reduce both the risks and costs associated with those hazards. The long-term 

mission of a comprehensive landslide hazard mitigation strategy is to provide and encourage 

the use of scientific information, maps, methodology, and guidance for emergency 

management, land-use planning, and development and implementation of public and private 

policy to reduce losses from landslides and other ground failure hazards nationwide. The 

10-year goal is to substantially reduce the risk of loss of life, injuries, economic costs, and 

destruction of natural and cultural resources that result from landslides and other ground 

failure hazards. 

A comprehensive National Landslide Hazards Mitigation Strategy employs a wide range of 

scientific, planning, and policy tools to address various aspects of the problem to effectively 

reduce losses from landslides and other ground failures. It has nine major elements, 

spanning a continuum from research to the formulation and implementation of policy and 

mitigation: 

1. Research: Developing a predictive understanding of landslide processes and triggering 

mechanisms.

2. Hazard Mapping and Assessments: Delineating susceptible areas and different types 

of landslide hazards at a scale useful for planning and decision-making

3. Real-Time Monitoring: Monitoring active landslides that pose substantial risk. 

4. Loss Assessment: Compiling and evaluating information on the economic impacts of 

landslide hazards. 

5. Information Collection, Interpretation, and Dissemination: Establishing an effective 

system for information transfer.

6. Guidelines and Training: Developing guidelines and training for scientists, engineers, 

and decision-makers.

7. Public Awareness and Education: Developing information and education for the user 

community

8. Implementation of Loss Reduction Measures: Encouraging mitigation action. 

9. Emergency Preparedness, Response, and Recovery: Building resilient communities.
viii

Table 1 on pages 25-26 describes the roles envisioned for Federal, State, and local 

governments, the private sector, and universities in each of the above nine elements. The 

USGS has a significant role in each element; however, the USGS is not the lead for all 

elements. 

Landslide hazard mitigation requires interactive collaboration across societal boundaries of 

academia, government, and the private sector. Aggressive implementation of a 

comprehensive and effective national landslide hazards mitigation strategy would require 

increased investment in landslide hazard research, mapping and monitoring, and mitigation 

activities. Reducing losses from landslide hazards can be accomplished in part by 

expanding the existing USGS Landslide Hazard Program ($2.2 million total appropriation in 

FY2000) as follows:

- Expansion of the research, assessment, monitoring, public information, and response 

efforts by USGS scientists ($8 million annually)

- Establishment of a Cooperative Landslide Hazard Assessment and Mapping Program to 

increase State and local governments efforts to map and assess landslide hazards within 

their jurisdictions through competitive grants ($8 million annually to be augmented with 

30% matching funds by the States and local jurisdictions)

- Establishment of a Cooperative Federal Land Management Landslide Hazard Program 

to increase the National Park Service, U.S. Forest Service, Bureau of Land Management, 

and other such organizations’ capabilities to address landslide hazards under their 

jurisdictions ($2 million annually for work performed by USGS scientists on public 

lands)

- Establishment of a Partnerships for Landslide Hazard Loss Reduction Program to 

support research and implementation efforts by universities, local governments, and the 

private sector through competitive grants ($2 million annually)

Total new funding required for full implementation of the National Landslide Hazards 

Mitigation Strategy within the USGS is estimated to be approximately $20 million annually.

An effective National Landslide Hazards Mitigation Strategy also depends on stronger 

partnerships among Federal, State, and local governments and the private sector in the areas 

of hazard assessments, monitoring, and emergency response and recovery. The strategy 

recommended in this report advocates enhanced coordination among Federal, State, and 

local agencies to partner effectively with the academic and the private sectors and leverage 

shared resources under the leadership of the USGS. 
ix

Massive Landslide at La Conchita, California - a small seaside community along Highway 101 north of Santa 

Barbara. This landslide and debris flow occurred in the spring of 1995. Many people were evacuated because 

of the slide, and the houses nearest the slide were completely destroyed. Fortunately, no one was killed or 

injured. (Photograph by R.L. Schuster, USGS)

,./
x

Landslide Overview Map of the Conterminous United States (USGS Open-file Report 97-289, digital compilation by Jonathan W. Godt, 1997). Different colors denote areas of varying landslide occurrence.
1

National Landslide Hazards Mitigation Strategy

A Framework for Loss Reduction

1. Introduction

Landslides and other forms of ground failure impact communities all across the 

Nation. Despite advances in science and technology, losses continue to result in 

human suffering, billions of dollars in property losses, and environmental 

degradation. As population increases and our society becomes ever more 

complex, the economic and societal costs of landslides and other ground failures 

will continue to rise. 

We have the capability as a Nation to understand and identify these hazards and 

implement mitigation measures. For many years, USGS, States, universities, 

and the private sector have been grappling with understanding and reducing 

landslide hazards, and an extensive body of knowledge exists. (See Appendix B 

for sources of information.) However, to achieve the goals of significantly 

reducing losses from landslide hazards, we need a much more comprehensive 

scientific understanding of landslides processes and occurrence, a robust 

monitoring program to warn of impending danger from active landslides, a much 

greater public awareness and understanding of the threat and options for 

reducing the risk, and action at the local level. 

A significant, sustained, long-term effort to reduce losses from landslides and 

other ground failures in the United States will require a national commitment 

among all levels of government and the private sector. The Federal government, 

in partnership with State and local governments, must provide leadership, 

coordination, research support, incentives, and resources to encourage 

communities, businesses, and individuals to undertake mitigation to minimize 

potential losses and to employ mitigation in the recovery following landslides 

and other natural hazard events. 

The USGS is the recognized authority for understanding landslide hazards in the 

United States and the long time leader in this area. The USGS derives its 

leadership role in landslide hazard related work from the Disaster Relief Act of 

1974 (Stafford Act). The Director of the USGS has been delegated the 

responsibility to issue disaster warnings for an earthquake, volcanic eruption, 

landslide, or other geologic catastrophe consistent with the 1974 Disaster Relief 

Act 42 U.S.C. 5201 et seq.
2

(Photograph by R.L. Schuster, USGS)

Massive Landslide at Thistle, Utah

The 1983 Thistle landslide began moving in the spring of 1983 in response to groundwater 

buildup from heavy rains the previous September and melting snowpack from the winter of 

1983. Within a few weeks, the landslide dammed the Spanish Fork River, obliterating U.S. 

Highway 6 and the main line of the Denver and Rio Grande Western Railroad. 

The town of Thistle was inundated under the floodwaters rising behind the landslide dam. 

Eventually a drain system was engineered to drain the lake and avert a potential disaster. 

The landslide reached a state of equilibrium across the valley, but fears of reactivation

caused the railway to construct a tunnel through bedrock around the slide zone at a cost of 

millions of dollars. Similarly, the highway was realigned around the landslide. When the 

lake was drained, residual muck partially buried the town and virtually no one returned to 

Thistle. 

Total costs (direct and indirect) incurred by this landslide exceeded $400 million, the most 

costly single landslide event in U.S. History. 
3

As requested by the Congress in House Report 106-222, the USGS has prepared 

this National Landslide Hazards Mitigation Strategy on behalf of the large multisector, multi-agency stakeholder group involved in landslide research and 

mitigation nationwide. A series of stakeholder workshops were held during 

1999 and 2000 with representatives of government and private organizations, 

academicians, and private citizens to seek their opinion and input. (See 

Appendix A for more information about the stakeholder workshops).

The National Landslide Hazards Mitigation Strategy (Strategy) provides a 

framework for reducing losses from landslides and other ground failures. 

Although the Strategy is national in scope, it is not exclusively Federal, or even 

exclusively governmental. Mitigation, defined as any sustained action taken to 

reduce and eliminate long-term risk to life and property, generally occurs at the 

State and local levels, and the Strategy is based on partnerships with 

stakeholders at levels of government and the private sector. 

The National Landslide Hazards Mitigation Strategy described here incorporates 

many ideas and recommendations of previous studies and reports that have 

expressed the need for a national strategy to address natural hazards, including 

landslides and other ground failures (see Appendix B). These studies and 

reports should be referred to for more in-depth discussions of and insights into 

landslide hazard mitigation and research needs. The National Landslide Hazards 

Mitigation Strategy builds on the principles, goals and objectives of the National 

Mitigation Strategy – Partnerships for Building Safer Communities developed in 

1996 by the Federal Emergency Management Agency (FEMA) to encourage 

mitigation of all forms of natural hazards in the United States. 

The term “landslide” describes many types of downhill earth movements, 

ranging from rapidly moving catastrophic rock avalanches and debris flows in 

mountainous regions to more slowly moving earth slides and other ground 

failures. In addition to the different types of landslides, the broader scope of 

ground failure includes subsidence, permafrost, and shrinking soils. This report 

focuses on landslides, the most critical ground failure problem facing most 

regions of the Nation. However, the National Landslide Hazards Mitigation 

Strategy provides a framework that can be applied to other ground failure 

hazards (see Appendix C for more information about different types of landslide 

hazards and other forms of ground failure). 
4

Debris flows like these near Glenwood Springs, Colorado, are a consequence of heavy 

rainfall on previously burned hillsides. (Photo: Jim Scheidt, U.S. Bureau of Land 

Management)

Wildfires and Debris-Flows

During the summer of 2000, numerous wildfires burned drought-parched areas of the

western United States. USGS scientists were enlisted to advise Federal and State emergency 

response teams on the potential for future debris flows in burned areas, such as Cerro Grande 

fire (Los Alamos, New Mexico) and Hi-Meadow and Bobcat fires (Colorado). 

Debris flows often occur during the fall and winter following major summer fires. One such 

combination of fires and debris flows occurred in July 1994, when a severe wildfire swept 

Storm King Mountain west of Glenwood Springs, Colorado, denuding the slopes of

vegetation. Heavy rains on the mountain the following September caused numerous debris 

flows, one of which blocked Interstate 70 and threatened to dam the Colorado River. A 3-

mile length of the highway was inundated with tons of rock, mud and burned trees. The 

closure of Interstate 70 imposed costly delays on this major transcontinental highway. The 

USGS assisted in analyzing the debris-flow threat and installing monitoring and warning 

systems to alert local safety officials when high-intensity rainfall occurred or debris flows 

passed through a susceptible canyon. Similar debris flows threaten other transportation 

corridors and other development in and near fire-ravaged hillsides. 

From USGS Fact Sheet 176-97 “Debris-Flow Hazards in the United States,” by Lynn M. 

Highland, Stephenson D. Ellen, Sarah B. Christian, and William M. Brown III
5

1.1. Losses from Landslide Hazards in the United States

Landslides are among the most widespread geologic hazard on Earth. 

Landslides cause billions of dollars in damages and thousands of deaths and 

injuries each year around the world. Landslides threaten lives and property in 

every State in the Nation, resulting in an estimated 25 to 50 deaths and damage 

exceeding $2 billion annually. Though most landslide losses in the United States 

accrue from many widely distributed events, thousands of landslides can be 

triggered by severe storms and earthquakes, causing spectacular damage in a 

short time over a wide area. 

The United States has experienced several catastrophic landslide disasters in 

recent years. In 1985, a massive slide in southern Puerto Rico killed 129 people, 

the greatest loss of life from a single landslide in U.S. history. The 1982-83 and 

1983-84 El Niño season affected the entire Western United States, including 

California, Washington, Utah, Nevada, and Idaho. The Thistle, Utah, landslide 

of 1983 caused $400 million in losses, the most expensive single landslide in 

U.S. history. And the 1997-98 El Niño rainstorms in the San Francisco Bay area 

produced thousands of landslides, causing over $150 million in direct public and 

private costs. 

Landslides represent a significant component of many major natural disasters 

and are responsible for greater losses than is generally recognized. Landslide 

damage is often reported as a result of a triggering event--floods, earthquakes, or 

volcanic eruptions--even though the losses from landsliding may exceed all other 

losses from the overall disaster. For example, flash floods in mountainous areas 

often have devastating debris flows. Also, most of the losses due to the 1964 

Alaska earthquake resulted from ground failure rather than from shaking of 

structures. Also, landslides associated with a major earthquake in Afghanistan 

and with Hurricane Mitch in Central America in 1998 caused the majority of 

fatalities in these disasters.

All 50 States and the U.S. Territories experience landslides and other ground 

failure problems; 36 States have moderate to highly severe landslide hazards. 

The greatest landslide damage occurs in the Appalachian, Rocky Mountain, and 

Pacific Coast regions and Puerto Rico. Seismically active mountainous regions, 

such as those in Alaska, Hawaii, and the West Coast are especially at risk. 

Extremely vulnerable are areas where wildfires have destroyed vegetation, 

exposing barren ground to heavy rainfall. 
6

Landslide in northwest Seattle, Washington. Foundation of house on right edge of

photograph and decks of neighboring houses have been undermined. 

(Photo by Alan F. Chleborad, USGS)

Project Impact: Building Disaster Resistant Communities 

An outstanding example of public-private partnerships is FEMA’s Project Impact. Nearly 

200 communities and more than 1,100 business partners have embraced Project Impact since 

its inception in 1997. Instead of waiting for disasters to occur, Project Impact communities 

take action to reduce potentially devastating disasters. Seattle, Washington, a city that is 

exposed to significant landslide hazards, was one of the first communities in the United 

States to join.

In conjunction with Project Impact, Seattle partnered with USGS to develop landslide hazard 

maps that will enable the city to become better prepared for landslide emergencies and 

reduce losses resulting from landslide disasters. The city made available information needed 

by USGS scientists to accurately assess landslide hazards in the area and to ultimately

produce a computer-based landslide hazard map, including Seattle's detailed topographic 

database and related geographic data, detailed precipitation data collected by the National 

Weather Service, GIS support for completing the maps, and a landslide database from city 

records that date back to the late 1800's. USGS scientists are analyzing city data along with 

other information to determine the degree of landslide hazard throughout the city. The 

scientists are also conducting studies to determine the probability that landslides will result 

from storms of different magnitudes. 

Project Impact has resulted in unprecedented awareness of landslide hazards by the private 

sector. For example, major mortgage bankers have realized that they hold mortgages on 

many properties in areas of significant landslide hazard in Seattle and elsewhere in the

United States, and are beginning to take steps to encourage homeowners to mitigate the 

hazards. 
7

Landslide losses are increasing in the United States and worldwide as 

development expands under pressures of increasing populations. This trend will 

continue due to development in hazardous areas, expansion of transportation 

infrastructure, deforestation of landslide-prone areas, and changing climate 

patterns. However, increase in the cost of landslide hazards can be curbed 

through better understanding and mapping of the hazards and improved 

capabilities to mitigate and respond to the hazards.

Landslides and other ground failures impose many direct and indirect costs to 

society. Direct costs include the actual damage sustained by buildings and 

property, ranging from the expense of cleanup and repair to replacement. 

Indirect costs are harder to measure and include business disruption, loss of tax 

revenues, reduced property values, loss of productivity, losses in tourism, and

losses from litigation. The indirect costs often exceed the direct costs. Much of 

the economic loss is borne by Federal, State, and local agencies that are 

responsible for disaster assistance and highway maintenance and repair. 

Landslides have a large adverse effect on infrastructure and threaten lifelines, 

including transportation corridors, fuel and energy conduits, and 

communications linkages. Federal, State, local, and private roads, bridges, and 

tunnels suffer economically devastating effects from landsliding every year. 

Railroads, pipelines, electric and telecommunication lines, dams, offshore oil 

and gas production facilities, port facilities, and waste repositories continually 

experience the consequences of land movement. Road building and construction 

often exacerbate the landslide problem in hilly areas by altering the landscape, 

slopes and drainages, and changing and channeling runoff, thereby increasing the 

potential for landslides. Landslides and others forms of ground failure, also have 

adverse environmental consequences such as dramatically increased soil erosion, 

siltation of streams and reservoirs, blockage of stream drainages, and loss of 

valuable watershed, grazing, and timber lands.

1.2. A National Strategy

Society is far from helpless in the face of these prospects. Improvements in our 

scientific understanding of landslides and other ground failure hazards can 

provide more accurate delineation of hazardous areas and assessments of their 

hazard potential. This information can be developed in a form and at a scale that 

is meaningful and useful for decisionmaking. Cost-effective actions can be 

taken to reduce the loss of lives and property, damage to the environment, and 
8

Debris-Flow Flume—Understanding Landslide Processes

USGS and U.S. Forest Service (USFS)

scientists recreate debris flows in a flume 

that has been constructed to conduct

controlled experiments. Located about 45 

miles east of Eugene, Oregon, in

Willamette National Forest in the

Cascades Range, this unique facility

provides research opportunities available 

nowhere else in the United States. USGS 

and USFS scientists conduct experiments 

to improve understanding of ground

vibrations caused by debris flows and to 

refine automated debris-flow detection

systems. The flume also provides an

ideal environment for testing landslide

controls that deflect, trap, or channelize 

debris flows. Experiments that assess

how debris flows react to and act upon 

such controls can be used to guide and 

evaluate engineering designs.

The debris-flow flume (pictured at right) 

is a reinforced concrete channel 95 meters 

(310 feet) long, 2 meters (6.6 feet) wide, 

and 1.2 meters (4 feet) deep that slopes 31 

degrees, an angle typical of terrain where 

natural debris flows originate. 

Removable glass windows built into the side of the flume allow flows to be observed and 

photographed as they sweep past. Eighteen data-collection ports in the floor of the flume 

permit measurements of forces due to particles sliding and colliding at the based of flows. 

Additional insight can be gained by using ultrasound imaging to “see” into the interior of 

flows and by deploying “smart rocks” containing miniature computers that record the rocks’ 

accelerations as they move down the flume. 

To create a debris flow, 20 cubic meters (about 40 tons) of saturated sediment are placed 

behind a steel gate at the head of the flume and then released. Alternatively, a sloping mass 

of sediment can be placed behind a retaining wall at the flume head and watered until slope 

failure occurs. The ensuing debris flow descends the flume and forms a deposit at the flume 

base. The flume design thus accommodates research on all stages of the debris-flow 

process, from initiation through deposition.

From USGS Open File Report 92-483 by R.M Iverson, J.E. Costa, and R.G. LaHusen, 1992.
9

economic and social disruption caused by landslides and other ground failures 

(see Appendix D for more information about mitigation techniques). 

Government at all levels plays critical roles in advancing landslide hazard 

mitigation and developing programs and incentives that encourage and support 

community-based implementation. A national strategy to reduce losses from 

landslides and other ground failures must have both research and implementation 

components to increase understanding of landslides and other ground failures 

and put existing knowledge to use to reduce losses. Developing durable and 

comprehensive solutions to landslides and other ground failure hazards will 

require a continuing dialogue among and concerted action by all sectors of our 

society. 

A new public-private partnership is needed at the Federal, State, and local level 

to foster continuing cooperation among geologists, engineers, hydrologists, 

planners, and decisionmakers regarding landslides and other natural hazards. 

This ongoing effort will over time help to ensure that the needed scientific and 

engineering information is developed in a form useful for planning and decisionmaking, and that such information is applied to mitigate these hazards. 

2. A National Landslide Hazards Mitigation Strategy 

The National Landslide Hazards Mitigation Strategy described herein envisions 

a society that is fully aware of landslide hazards and routinely takes action to 

reduce both the risks and costs associated with those hazards. The Strategy 

envisions bringing together relevant scientific, engineering, construction, 

planning, and policy capabilities of the Nation to eliminate losses from 

landslides and other ground failure hazards nationwide.

The long-term mission of such a strategy is to provide and encourage the use of 

scientific information, maps, methodology, and guidance for emergency 

management, land-use planning, and development and implementation of public 

and private policy to reduce losses from landslides and other ground failure 

hazards nationwide. 
10

Mapping Debris-Flow Hazards in Madison County, Virginia

A major landslide event occurred in Madison County, Virginia, in the summer of 1995. 

During an intense storm on June 27th, thirty inches of rain fell in 16 hours. In mountainous 

areas, rain-saturated landslides known as debris flows were triggered by the hundreds,

causing extensive devastation and one fatality.

Historical records tell us that destructive landslides and debris flows in the Appalachian 

Mountains occur when unusually heavy rain from hurricanes and intense storms soaks the 

ground, reducing the ability of steep slopes to resist the downslope pull of gravity. For 

example, during Hurricane Camille in 1969, such conditions generated debris flows in 

Nelson County, Virginia, 90 miles south of Madison County. The storm caused 150 deaths, 

mostly attributed to debris flows, and more than $100 million in property damage. Likewise, 

72 hours of storms in Virginia and West Virginia during early November 1985 caused debris 

flows and flooding in the Potomac and Cheat River basins that were responsible for 70

deaths and $1.3 billion in damage to homes, businesses, roads, and farmlands.

Section of debris-flow hazard map, Madison County, Virginia (USGS I-2623B, by 

B.Morgan, G.Wieczorek, and R.Campbell, 1999).

Scientists from the USGS have developed an inventory of landslides, debris flows, and

flooding from the storm of June 27, 1995, by using aerial photography, field investigations, 

rainfall measurements from rain gages, and National Weather Service radar observations. 

This inventory and a new debris-flow hazard map are being used to help understand the 

conditions that led to the floods and debris flows caused by the 1995 summer storms in 

Virginia and to suggest methods of mitigating the effects of such events in the future. 

USGS Fact Sheet FS-159-96 “Debris-Flow Hazards in the Blue Ridge of Virginia” by Paula 

L. Gori and William C. Burton
11

2.1. Major Elements and Strategic Objectives 

2.1.1. Reaching the Goal

The strategic plan described in this report has nine major elements, spanning a 

continuum from research to the formulation and implementation of policy and 

mitigation objectives. 

Implementation of such a strategy will demand a multiyear coordinated public 

and private effort. All levels of government and the private sector share 

responsibility for addressing these priorities and accomplishing the objectives. 

Some of the objectives consist of a single, discrete action; others encompass a 

series of interdependent actions to be taken over the first 10 years. Although the 

primary focus is on landslide hazards, the National Strategy provides a 

framework for addressing other forms of ground failure as well.

The USGS has a role in each of the nine elements as a provider of landslide 

hazard information; however, the lead and participants in each element differs 

with the nature of the element.

2.1.2. Elements and Objectives

 1. Research: Developing a predictive understanding of landslide processes 

and triggering mechanisms, led by USGS. Hazard identification is a 

cornerstone of landslide hazard mitigation. Although many aspects of 

landslide hazards are well understood, a much more comprehensive 

understanding of landslide processes and mechanisms is required to truly 

advance our ability to predict the behavior of differing types of landslides. 

The following actions would increase the Nation’s capability to forecast 

landslide hazards through enhanced research and application of new 

technology and understanding of landslide processes, thresholds, and 

triggering mechanisms. 

- Develop a national research agenda and a multi-year implementation 

plan based on the current state of scientific knowledge concerning 

landslide hazard processes, thresholds, and triggers, and the ability to 

predict landslide hazard behavior. 

- Develop improved, more realistic scientific models of ground 

deformation and slope failure processes, and implement their use in 

predicting landslide hazards nationwide.
12

 Real-Time Monitoring of Active Landslides

Five landslides that threaten U.S. Highway 50 

and nearby homes in Sierra Nevada, California, 

are being monitored by USGS after heavy rains 

in January 1997 generated debris flows that

blocked Highway 50. The cost of reopening the 

highway was $4.5 million, with indirect

economic losses from closure of the highway

amounting to an additional $50 million. To

monitor the risk posed by landslides in this area, 

the USGS, in cooperation with other local, State, 

and Federal agencies, provide continuous realtime monitoring of landslide activity using a

system developed by the USGS for monitoring 

active volcanoes in remote areas.

This system measures ground movement and

ground water pressures every second. Slope

movement is recorded by instruments that detect 

stretching and shortening of the ground. 

Ground vibrations caused by slide movement

are monitored by geophones buried within the 

slide. Ground-water conditions within the slides 

are monitored by sensors, and rain gauges

record precipitation. Under normal conditions, 

data are transmitted to USGS computers every

10 minutes, but if strong ground vibrations

caused by massive landslide movement are

detected, data are transmitted immediately. 

The USGS operates other remote real-time 

landslide monitoring sites. Near Seattle, WA, a 

real-time system monitors a slide threatening a

major railway, and in Rio Nido, CA, another

system monitors a large landslide threatening

more than 140 homes. Remote monitoring also 

can record the effects of wildfire in destabilizing 

on slopes. 

Measuring landslide movement. 

(Photo by Richard LaHusen, USGS)

Testing a solar-powered radio telemetry 

system for remote transmission of realtime landslide data. (Photo by Mark Reid, 

USGS)

Network for transmission of real-time 

landslide data

From USGS Fact Sheet 091-99, by M. 

Reid, R. LaHusen, and W. Ellis.
13

- Develop dynamic landslide prediction systems capable of interactively 

displaying changing landslide hazards in both space and time in areas 

prone to different types of landslide hazards (for example, shallow debris 

flows during intense rain, deep-seated slides during months of wet 

weather, and rock avalanches during an earthquake). 

 2. Hazard Mapping and Assessments: Delineating susceptible areas and 

different types of landslide hazards at a scale useful for planning and 

decision-making, led by USGS and State geological surveys. Landslide 

inventory and landslide susceptibility maps are critically needed in landslide 

prone regions of the nation. These maps must be sufficiently detailed to 

support mitigation action at the local level. To cope with the many 

uncertainties involved in landslide hazards, probabilistic methods are being 

developed to map and assess landslide hazards (see Appendix E for more 

information about mapping and assessing landslide hazards). Risk 

assessments estimate the potential economic impact of landslide hazard 

events. Landslide inventory and susceptibility maps and other data are a 

critical first step and prerequisite to producing probabilistic hazard maps and 

risk assessments, but these maps and data are not yet available in most areas 

of the United States. 

The following actions would provide the necessary maps and assessments, and 

other information to officials and planners to reduce risk and losses. 

- Develop and implement a plan for mapping and assessing landslide and 

other ground-failure hazards nationwide. 

- Develop an inventory of known landslide and other ground-failure 

hazards nationwide. 

- Develop and encourage the use of standards and guidelines for landslide 

hazard maps and assessments.

 3. Real-Time Monitoring: Monitoring active landslides that pose 

substantial risk, led by USGS. Monitoring of active landslides serves the 

dual purpose of providing hazard warning in time to avoid or lessen losses, 

as well as supporting landslide research by providing new insights into 

landslide processes and triggering mechanisms. Collection of rare dynamic 

movement behavior data enables the testing of landslide velocity models and 

the development of improved predictive tools applicable to other slides. 

Development and application of real-time monitoring of 
14

Inventory of Slope Failures in Oregon for Three 1996/97 Storm Events

Three significant Pacific Northwest storm events in February 1996, November 1996, and 

late December 1996 and early January 1997 initiated widespread slope failures throughout 

Oregon. Each of these storms received a "Major Presidential Disaster Declaration,” and 

damages to natural resources and infrastructure were extreme. In the Portland metropolitan 

region, Oregon’s largest city, more than 700 slope failures were associated with the heavy 

rains in 1996, with 17 houses completely destroyed and 64 partially condemned. An

estimate of statewide public and private damages incurred from the February 1996 event 

alone is $280 million. 

To better characterize the distribution and magnitude of the slope failures associated with the 

three storms, FEMA provided funding for the consolidation of a landslide inventory. The 

Oregon Department of Geology and Mineral Industries led the consolidation effort and 

utilized various methods to contact potential data sources, inform them of the existence of 

the study, and request their participation. 

Landslide inventory for three 1996/97 storm events in Oregon.

Over nine thousand landslide locations were incorporated into the inventory, with varying 

amounts of information reported for each. Many other slides were not observed or recorded 

and it is expected that two to three times this many landslides occurred during the time 

period. As shown on the schematic map, the vast majority (98%) of the entries are in the 

western portion of the state. Most of these slides occurred in the Oregon Coast Range and 

Cascade Province with fewer in the Willamette Valley and Klamath Mountains. 

This inventory will help lead to a greater understanding of regional landslide issues and 

assist government and community agencies in devising means to minimize the threat to 

public health and property that landslides pose. 

From Hofmeister, R.J., 2000,“Database of Slope Failures in Oregon for Three 1996/97

Storm Events,” Oregon Department of Geology and Mineral Industries. 
15

active landslides using state-of-the-art research and telecommunications 

technologies is critically needed nationwide in cases of imminent risk. 

The following actions would provide the necessary warning and other 

information to officials and communities to avoid or reduce losses. 

- Develop and implement a national landslide hazard monitoring and 

prediction capability.

- Develop real-time monitoring and prediction capabilities on both sitespecific and regional scales, to assist Federal, State, and local emergency 

managers determine the nature of landslide hazards and the extent of 

ongoing risks.

- Apply remote sensing technologies such as Synthetic Aperture radar and 

laser altimetry for monitoring landslide movement nationwide.

- Incorporate state-of-the-art techniques such as microseismicity, rainfall 

and pore-pressure monitoring integrated with hydrologically based 

models of slope stability and Global Positioning Systems (GPS). 

- Integrate real-time monitoring capabilities with the National Weather 

Service’s NEXRAD capabilities in selected locations nationwide.

 4. Loss Assessment: Compiling and evaluating information on the 

economic impacts of landslide hazards, led by FEMA and insurance 

industry. Although losses from landslides and other natural hazards are 

frequent and widespread, these losses are not consistently compiled and 

tracked in the United States. Following a landslide or other natural hazard 

event, a variety of different agencies and organizations may provide damage 

estimates, but these estimates usually vary widely, cover a range of different 

costs, and change through time. The National Research Council concluded 

in their 1999 report, “The Impact of Natural Disasters A Framework for 

Loss Estimation,” that there is no widely accepted framework for estimating 

the losses from natural disasters, including landslide and other ground failure 

hazards. This lack of information makes it difficult to set policies for coping 

with these hazards and difficult to gauge the cost-effectiveness of policy 

decisions and effectiveness of mitigation measures. Loss data is critically 

needed to help government agencies identify trends and track progress in 

reducing losses from landslides.

The following actions would provide a framework for compiling and 

assessing a comprehensive data base of losses from landslides and other 

ground failure hazards, which will help guide research, mapping, and 

mitigation activities nationwide.
16

Debris flow in Pacifica, California, about 10 miles south of San Francisco, 

where three children were killed and two homes destroyed on January 4, 

1982. From USGS Fact Sheet 112-95. Photograph by Gerald Weizorek.

Warning of Potential Landslides

An experimental monitoring and warning system was developed and operated jointly by the 

USGS and the National Weather Service (NWS) from the 1980s to 1995 in the San

Francisco Bay Region. The system used NWS protocols and outlets for issuing warnings, 

and regional networks of NWS and USGS rain gages and soil-moisture instruments to track 

rainfall and soil-moisture conditions. Rainfall thresholds for triggering landslides were

determined based on observed relationships between rainfall intensity and duration and the 

occurrence of landslides. When real-time data and high-precision forecasting by the NWS 

indicated that the rainfall threshold for landslides had or would soon be reached, USGS 

scientists informed the NWS to issue a warning through normal media channels. The media, 

government officials, and the general public in the Bay Area came to rely on these warnings 

and took specific actions such as evacuating neighborhoods at particular risk.

Under the National Landslide Hazards Mitigation Strategy, next-generation landslide

warning systems will be implemented in landslide-prone regions nationwide. Precipitation, 

soil moisture, and pore-pressure data will telemetered in real time to network centers for 

processing and analysis. These measurements will help define the precipitation thresholds 

and supplement NEXRAD and other precipitation data and forecasts provided by NWS or 

local agencies. Warnings of potential landslide activity that might be triggered by storms or 

extended rainy periods will be issued in cooperation with the NWS and Federal and State 

emergency management agencies. 
17

- Assess the current status of data on losses from landslides and other 

ground failures nationwide, including the types and extent of losses to 

public and private property, infrastructure, and natural and cultural 

resources. 

- Establish and implement a national strategy for compilation, 

maintenance, and evaluation of data on the economic and environmental 

impacts of landslide and other ground failure hazards nationwide to help 

guide mitigation activities and track progress. 

 5. Information Collection, Interpretation, Dissemination, and Archiving: 

Establishing an effective system for Information Transfer, led by USGS 

and State geological surveys. Collecting and disseminating landslide 

hazards information to Federal, State and local government agencies, 

nongovernmental organizations, planners, policy makers private citizens in a 

form useful for planning and decision-making is critically important to an 

effective mitigation program. Although landslide hazards have been studied 

for decades, systematic collection and distribution of scientific and technical 

information is in its relative infancy. The USGS National Landslide 

Information Center is a prototype system that can be enhanced and extended 

into a robust nationwide system for collection, interpretation, and 

dissemination of landslide hazard maps, assessments, and other scientific and 

landslide hazard technical information. 

The following objectives will make available landslide hazard information in 

a form useful to scientists, officials, decision-makers, and the public to assist 

research, planning, policy, and mitigation activities. 

- Evaluate and use state-of-the-art technologies and methodologies for the 

dissemination of technical information, research results, maps, and realtime warnings of potential landslide activity. 

- Develop and implement a national strategy for the systematic collection, 

interpretation, archiving and distribution of this information. 

 6. Guidelines and Training: Developing guidelines and training for 

scientists, engineers, and decisionmakers, led by USGS and professional 

societies. The science of landslide hazards is an area of active research and 

technological application, and there is a critical need for guidelines and 

training for scientists and engineers in development of landslide maps and 

assessments. Hazard assessments involve assumptions and
18

Hazard zones from lahars, lava flows, and pyroclastic flows from Mount 

Rainier (USGS Open-File Report 98-428 by Hoblitt and others, 1998)

Alerting the Public to the Hazards of Mount Rainier

Mount Rainier in Washington is an active volcano that is currently at rest between eruptions. 

Its next eruption may produce volcanic ash, lava flows, or pyroclastic flows. Pyroclastic flows 

are hot avalanches of lava fragments and gas formed by volcanic eruptions. Pyroclastic flows 

can rapidly melt snow and ice, and the resulting meltwater torrent may produce lahars (the 

widely used Indonesian word for volcanic mudflows and debris flows) that travel down valleys 

beyond the base of the volcano. Lahars may also occur during non-eruptive times when a 

section of the volcano collapses.

Lahars look and behave like rapidly flowing concrete, and their impact can destroy most manmade structures. Historically at Mount Rainier, they have traveled 45-50 miles/hr with

thicknesses of 100 feet or more in confined valleys, slowing and thinning as they flowed into 

wider valleys that are now populated. At Mount Rainier, lahars are a greater hazard than other 

volcanic hazards such as lava and poisonous gases.

The likely courses of lahars will be the river valleys that drain Mount Rainier. Four of the five 

major river systems flow westward into suburban areas of Pierce County. The USGS mapped 

the likely flow pathways and has joined with local, county, and state agencies to develop a 

Mount Rainier hazards plan that will address such issues as emergency response operations 

and strategies for expanded public awareness and mitigation. From USGS Fact Sheet 065-97 

“Mount Rainer—Living with Perilous Beauty” by K.M. Scott, E.W. Wolfe, and C.L Driedger. 
19

calculations about the magnitude and return frequency in specific geographic 

settings. Risk assessments involve assumptions about the potential physical 

and economic impacts of landslide hazard events. The development and 

presentation of the results in terms that are useful to citizens and decisionmakers are critically important to effective mitigation. Likewise, 

development of guidelines and training for planners and other decisionmakers in the use of these maps and assessments is important to encouraging 

its appropriate use by the user community.

The following are high priority objectives related to guidelines and training. 

- Develop and implement guidelines and training for scientists and 

geotechnical engineers in the use of landslide hazard and other technical 

information for mapping and assessing landslide hazards.

- Develop and implement guidelines and training for scientists and 

geotechnical engineers for responding to landslide disasters and 

providing needed scientific and technical information for response and 

recovery efforts.

- Develop and implement guidelines and training for planners and 

decision-makers in the use of landslide hazard maps, assessments, and 

other technical information for planning, preparedness, and mitigation.

 7. Public Awareness and Education: Developing information and 

education programs for the user community, led by FEMA and USGS. 

Before individuals and communities can reduce their risk from landslide 

hazards, they need to know the nature of the threat, its potential impact on 

them and their community, their options for reducing the risk or impact, and 

how to carry out specific mitigation measures. Achieving widespread public 

awareness of landslide hazards will enable communities and individuals to 

make informed decisions on where to live, purchase property, or locate a 

business. Local decisionmakers will know where to permit construction of 

residences, business, and critical facilities to reduce potential damage from 

landslide hazards.

The following actions would raise public awareness of landslide hazards and 

encourage landslide hazard preparedness and mitigation activities 

nationwide, tailored to local needs. 

- Develop public awareness, training, and education programs involving 

land use planning, design, landslide hazard curriculums, landslide hazard 

safety programs, and community risk reduction.
20

 Earthflow in Cincinnati, Ohio. Material being removed by highway crew.

Cincinnati, Ohio—a Leader in Landslide Loss Reduction Measures

Landslides are a significant problem in several areas of Ohio and Cincinnati has one of the 

highest per-capita costs due to landslide damage of any city in the United States. Landslides 

have been known to occur in the Cincinnati area in southwestern Ohio and adjoining States 

of Kentucky and Indiana since before the 1850’s, but the damage caused by landslides

became increasingly expensive as urban development encroached more and more on the 

area’s hillsides. The City of Cincinnati spent an average of about $550,000 per year on 

emergency street repairs for damage due to landslides between 1983 and 1987.

In 1974 the Cincinnati City Council passed an excavation and fill ordinance to help reduce 

landslide damage in areas of new construction. In 1989 Cincinnati created a geotechnical 

office within its Department of PublicWorks. The office, which is staffed by a geotechnical 

engineer, and engineering geologist, and two technicians, carries out a mitigation program. 

Since 1989, members of the geotechnical staff have worked in several ways to reduce

landslide damage in the city; their work includes engineering-geologic mapping of selected

parts of the city, inspection of retaining walls that impact public right-of-way, review of 

proposed construction in hillside areas, inspecting and arranging for repair of landslide areas 

that affect city property, and compiling geologic and geotechnical data on landslide areas 

within the city. In 1990, Hamilton County also adopted an excavation and fill ordinance to 

help reduce the damage due to landslides in areas of new construction.

From Ohio Department of Natural Resouces “Geofacts,” no. 8, by Michael C. Hansen,

September 1995 and USGS Bulletin 2059-A “Overview of Landslide Problems, Research, 

and Mitigation, Cincinnati, Ohio, Area” by Rex L. Baum and Arvid M. Johnson, 1996.
21

- Evaluate the effectiveness of different methods, messages, and 

curriculums in the context of local needs.

- Disseminate landslide hazard-related curriculums and training modules 

to community organizations, universities, and professional societies and 

associations.

 8. Implementation of Loss Reduction Measures: Encouraging mitigation 

action, led by FEMA, State departments of emergency services, and 

professional societies. A successful strategy for reducing landslide losses 

must also include a mitigation component. Mitigation actions generally fall 

to State and local governments, businesses, and individuals. As a result, 

societal attitudes and perceptions can present formidable obstacles to 

landslide hazards reduction. Few communities have considered the full 

range of mitigation options despite their feasibility and cost effectiveness. 

Mitigation measures at the local level include a range of tools and techniques 

such as land-use planning, regulation of development, engineering controls, 

building codes, assessment districts, emergency planning and warning, 

private financial and insurance incentives and disincentives, and other 

methods. The following actions would facilitate and encourage 

implementation of appropriate and effective mitigation measures that are 

tailored to local needs. 

- Evaluate impediments to effective planning and controls on development 

and identify approaches for removing those impediments.

- Develop an education program for State and local elected and appointed 

officials that sensitizes them to the risk and costs of landslide hazards 

and encourages them to develop legislation and policies that support 

effective landslide hazard mitigation.

- Develop and disseminate prototype incentives and disincentives for 

encouraging landslide mitigation to government agencies, private sector 

and academia.

- Evaluate engineering and construction approaches to mitigate landslide 

hazards and develop a national plan for research to improve these 

techniques. 

- Encourage implementation of successful landslide mitigation 

technologies.
22

Daly City—the Human Cost of Landslides

Active landslides pose an increasing problem to older communities. An example of this 

dilemma came to a head in April, 2000, when 21 late-1950s era homes in Daly City, CA, 

were condemned because of continued landsliding along Westline Drive. The homes were 

deemed permanently uninhabitable, and the city had no choice but to get the people out of 

imminent danger. By May, all residents had moved.

The Westline Drive landslide first grabbed the attention of Daly City residents in 1966, when 

sliding forced the removal of homes from a subdivision developed just 7 years earlier. One 

more home was removed in 1980. The movement lessened until the El Niño winter of 1997-

98, one of the wettest rainy seasons on record, caused the landslide to reactivate resulting in 

Westline Drive dropping as much as four feet at certain locations.

The recent decision by the city to condemn the houses was in reaction to the local gas 

utility’s decision to shut off gas service in February on the effected area of Westline drive 

after finding numerous irreparable leaks. The utility feared that pipe ruptures would cause 

an explosion. In addition, the city closed off the street to traffic including garbage and 

emergency vehicles after discovering a 10-foot-square cavity with up to 8 inches beneath the 

pavement. 

Assisting the homeowners will be a challenge. No insurance is available. The Federal

Emergency Management Agency offered to buy the homes, but funds will only cover a part 

of the previous value of the homes. The Federal Small Business Administration offered 

mortgage loans at 4%, but for a reduced value of the homes and the homeowners must pay 

off their existing mortgages. Daly City and San Mateo County plan to supplement the 

Federal government’s $6.5 million offer of assistance with housing funds totaling $1 million. 

If the city is successful, it will take over the deeds from the homeowners and turn the land 

into open space. 

From San Francisco Chronicle, March 30 and May 2, 2000, Angelica Pence, Staff Writer, 

and Russell Graymer, USGS. Photograph of Daly City in 1998, by S. Ellen, USGS.
23

9. Emergency Preparedness, Response, and Recovery: Building resilient 

communities, led by FEMA and State departments of emergency 

services. Despite improved landslide hazard mitigation, disasters will occur. 

For this reason, governments at all levels, the private sector, and the public 

will need to be able to adequately prepare for, respond to, and recover from 

disasters involving landslides. Governments will need to better plan for 

landslide emergencies. Scientists, engineers, and emergency response 

professionals will need to be trained in the best practices to employ during a 

response. And public officials responsible for recovery from disasters will 

need to be informed of options that will reduce future landslide losses. 

Incorporating the following actions in a national landslide mitigation strategy 

would improve the nation’s ability to respond to, and recover from landslide 

disasters.

- Provide training for Federal, State, and local emergency managers on 

landslide hazards preparedness, response, and recovery.

- Develop a coordinated landslide rapid response capability to assist local, 

State, and Federal emergency managers in determining the nature of 

landslide hazards and the extent of ongoing risks.Provide dedicated 

landslide expertise and equipment required for rapid emergency 

deployment of real-time data to emergency managers, as well as the 

ability to successfully transfer monitoring technology to other agencies.

3. Action Items for a National Strategy for Reducing 

Losses from Landslides

3.1. Key Steps for Implementation

Landslide hazard mitigation necessitates interactive collaboration across societal 

boundaries between academia and industry and government and the private 

sector. The following key aspects of a National Landslide Mitigation Strategy 

would allow for rapid and significant progress toward a sustained mitigation of 

landslide hazards nationwide:

- Conduct Federal-State and public-private forums to establish regional 

priorities for research, mapping, monitoring, forecasting, and mitigating 

landslide hazards.

- Establish new and enhance existing programs to fund research, mapping, 

monitoring, and mitigation activities nationwide. Develop Federal-State and 
24

public-private programs to delineate landslide prone areas, to forecast the 

potential for landslides, and to mitigate losses. 

- Establish and enhance Federal-State and public-private partnerships to 

leverage and maximize relevant resources and expertise.

3.2. Management Plan

Durable and effective solutions to the Nation’s ground-failure hazards problems 

will require a continuing dialogue among and concerted action by all sectors of 

our society. An effective National Landslide Hazards Mitigation Strategy will 

require a combination of purposeful management to ensure coordination, and 

consortium-type decision making to accommodate the multi-jurisdictional, 

cooperative nature of the Program. An effective management plan would 

include the following:

- Establish coordination of the National Landslide Hazards Mitigation 

Strategy under the leadership of the USGS, because of its expertise and 

experience in landslide hazards research, monitoring, mapping, data 

collection, analysis, archiving and dissemination. 

- Establish working groups with representatives of Federal, State, and local 

governments, academia, and private industry to help coordinate and guide 

the National Landslide Hazards Mitigation Strategy.

- Establish Federal-State Public-Private cooperative programs to fund and 

encourage landslide hazard research, mapping, assessment, and mitigation 

efforts nationwide.

3.3. New and Enhanced Roles and Partnerships

Many different Federal, State, and local agencies, academia, as well as private 

companies, are involved in landslide research and mitigation in the United States 

(see Appendix F for more information about Federal, State, and local programs). 

A National Landslide Hazards Mitigation Strategy offers new opportunities for 

mutually advantageous partnerships relating to hazard assessments, monitoring, 

and emergency response and recovery. 

The National Strategy enhances coordination among Federal, State and local 

agencies to partner effectively with the academic and the private sectors and to 

leverage shared resources. Table 1 outlines the complementary and supportive 

roles and opportunities for new partnerships for each participant in the National 

Landslide Hazards Mitigation Strategy.
25

Table 1. New Roles and Partnership Opportunities under the National Landslide Hazards Mitigation Strategy

New Roles and Partnership Opportunities

ELEMENT CURRENT 

STATUS Federal State Local Private Academic

Coordinate research priorities.

Conduct research.

1) Research: 

Developing a predictive 

understanding of landslide 

processes and triggering 

mechanisms.

A much more 

comprehensive 

understanding of 

landslide processes and 

mechanisms is required 

to advance our ability to 

predict the behavior of 

differing types of 

landslides.

Use results of research in policy, planning, and mitigation decisions.

Map landslides on Federal 

lands.

Establish mapping and assessment standards.

Map and assess landslide hazards.

2) Hazard Mapping and 

Assessments: Delineating 

susceptible areas and 

different types of landslide 

hazards at a scale useful for 

planning and 

decisionmaking.

Landslide inventory and 

landslide susceptibility 

maps are critically 

needed in many 

landslide prone regions 

of the nation. In general, 

there are no standards 

for mapping and 

assessments.

Use landslide hazard maps and assessments in planning, preparedness, and mitigation.

3) Real-Time Monitoring: Improve real-time monitoring capabilities.

Monitoring active 

landslides that pose 

substantial risk. 

Real-time monitoring of 

active landslides is 

critically needed 

nationwide.

Monitor landslides and establish landslide warning systems.

Establish and implement a 

national strategy for 

compilation, maintenance, 

and evaluation of data.

4) Loss Assessment:

Compiling and evaluating 

information on the 

economic and 

environmental impacts of 

landslide hazards.

Losses are not 

consistently compiled 

and tracked in the U.S. 

Compile and share records of losses.
26

Table 1 (continued). New Roles and Partnership Opportunities under the National Landslide Hazards Mitigation Strategy

New Roles and Partnership Opportunities

ELEMENT CURRENT 

STATUS Federal State Local Private Academic

5) Information Collection, 

Interpretation, 

Dissemination, and 

Archiving: Establishing an 

effective system for 

information transfer.

No systematic collection 

and distribution of 

landslide hazards 

information nationwide.

Develop robust landslide hazards information 

clearinghouse system for the systematic collection, 

interpretation, archiving and distribution of scientific 

and technical information, databases, and maps.

Collect and distribute needed information to 

decisionmakers.

Develop and share 

information.

6) Guidelines and Develop and implement guidelines and training curriculums.

Training: Developing 

guidelines, training for 

scientists, engineers, and 

decision makers. 

Critical need for 

guidelines and training 

for scientists, engineers, 

planners and decision 

makers.

Participate in training programs.

7) Public Awareness and 

Education: Developing 

information and education 

for the user community.

Little public awareness 

and understanding of 

landslide hazards, 

impacts on 

communities, and 

options for reducing 

risk.

Develop and implement public awareness and education programs, involving land use planning, design, and landslide hazard curriculums, 

landslide hazard safety programs, and community risk reduction.

Adopt and implement policies and practices that support 

landslide hazards mitigation.

8) Implementation of Loss 

Reduction Measures: 

Encouraging mitigation 

action.

Mitigation necessarily 

occurs at the local level, 

therefore, 

implementation of 

landslide hazards loss 

reduction measures 

varies from community 

to community. 

Develop and encourage policies that support landslide 

hazard mitigation.

Develop financial incentives and disincentives that 

support landslide hazard mitigation.

Develop and encourage engineering and construction 

approaches to mitigate landslide hazards. 

Serve as consultants and advisors. 

9) Emergency Participate in training. Provide expertise during emergencies.

Preparedness, Response, 

and Recovery: 

Developing resilient 

communities.

Federal, State and local 

governments, the 

private sector, and the 

public need to be able to 

adequately prepare, 

respond to, and recover 

from landslide 

emergencies.

Provide training for Federal, State and local emergency 

managers. 

Develop a coordinated landslide rapid response 

capability, including landslide hazards expertise and 

equipment required for rapid emergency deployment of 

real-time data to emergency managers.

Effectively respond to landslide emergencies. Implement 

policies that reduce future landslide losses. 
27

3.4. Funding for the USGS to Implement a National Strategy for 

Reducing Losses from Landslides

Implementation of the National Landslide Hazards Mitigation Strategy within the 

USGS Landslide Hazards Program (LHP) involves four principal tasks described 

below which would require expansion of the Program and additional funding. The 

USGS Landslide Hazard Program is currently funded for $2.2 million in FY 2000.

3.4.1. Expansion of Work Performed by Scientists in the Landslide 

Hazards Program.

Expanding efforts by USGS scientists in the areas of research, hazard 

assessment, monitoring, public information, and response will be necessary 

to meet the challenges of the National Strategy. The Landslide Hazards 

Program will also require additional funding to meet new responsibilities to 

coordinate activities within the Federal government to fully implement the 

National Strategy. Approximately $8 million in new funding would be 

required to support:

- Additional research on landslide processes and triggering mechanisms 

(Element 1, pg 11) ($1.5 million).

- Additional hazard maps and assessments of landslide susceptible areas 

including developing standards and guidelines (Element 2, pg 13) ($2 

million).

- Additional monitoring of active landslides and improvement of state-ofthe-art research and telecommunications technology (Element 3, pg 13-

15) ($2 million).

- Improved information collection, interpretation, dissemination, and 

technology transfer including public awareness and education (Elements 

5 and 7, pg 17 & 19) ($1 million).

- Expanded emergency response and recovery capability and activities 

(Element 9, pg 23) ($1 million).

- Coordination of National Landslide Hazard Mitigation Strategy 

(Management Plan Section 3.2, pg 24) ($0.5 million).

3.4.2. Establishment of new Cooperative Landslide Hazard Assessment 

and Mapping Program

Establish a new cooperative program administered by the USGS Landslide 

Hazards Program to encourage understanding and mitigation of landslide 

and other ground-failure hazards by States, Territories, Counties and other 

local jurisdictions. 

The primary goal of this program would be to reduce losses by increasing 

the availability of assessments and maps of landslide- and other groundfailure prone areas in the United States at a scale necessary to implement 

hazard loss reduction policies. This program will address all elements of the 

National Strategy, with a primary focus on element 2, landslide hazard 

mapping and assessments. USGS would provide guidance to encourage 

standardized assessment and map products that will be available digitally.
28

Priorities would be determined annually in consultation with State and 

Territory representatives. Grants to States and Territories would be awarded 

competitively. States and Territories would determine their priorities and 

sizes of grants to be distributed to their local jurisdictions in consultation 

with State- and Territory-wide advisory committees.

Approximately $8.0 million would be required to support competitive grants 

to the States, Territories and local jurisdictions each year. Each grant would 

be matched by a 30% State or Territory contribution, in order to encourage 

the development and use of landslide information in planning and mitigation 

actions at the State and local levels. It is anticipated that all States and 

Territories would participate in such a program resulting in grants of varying 

sizes with an average grant of about $150,000 per State or Territory. 

3.4.3. Establishment of new Cooperative Federal Land Management 

Landslide Hazard Program

Establish a new program administered by the USGS Landslide Hazards 

Program to increase and encourage the understanding and mitigation of 

landslide hazards on Federal lands, including assessment and mapping of 

landslides, land-use planning and facility siting, emergency management, 

and public education.

The goal of such a program would be to reduce losses from landslide and 

other ground-failure hazards through more informed and, therefore, better 

stewardship of Federal lands under the jurisdiction of the National Park 

Service, the Bureau of Land Management, The Bureau of Reclamation, the 

Bureau of Indian Affairs, and the U.S. Forest Service. The program would 

address all elements of the National Strategy, with a primary focus on 

landslide hazard mapping, assessments, and monitoring (elements 2 and 3).

Priorities for scientific and technical assistance for Federal land management 

agencies would be determined annually in consultation with representatives 

of Federal land management agencies. 

Approximately $2.0 million would be required for scientific and technical 

assistance for Federal land management agencies. It is anticipated that the 

program will support approximately 20 agreements of varying sizes 

averaging about $100,000 each. It is anticipated that most of these funds 

would go to supporting hazard assessments, and monitoring equipment with 

USGS staff providing the technical assistance.

3.4.4. Establishment of new Partnerships for Landslide Hazard Loss 

Reduction Program

Establish a new competitive external grants program administered by the 

USGS landslide Hazards Program for research and application of research. 

The program would foster partnerships with universities, private consulting
29

firms, professional associations, Federally Recognized Indian Tribal 

Governments, States and Territories, and local agencies.

This program would address all elements of the Strategy, with a primary 

focus on landslide hazard research and development and application of 

mitigation measures (elements 1, 2, 8).

Priorities for research and application of research would be determined 

annually in consultation with Federal, State, Territory, local, and private 

representatives. 

Approximately $2.0 million would be required for cooperative agreements 

with universities, private consulting firms, professional associations, 

Federally recognized Indian Tribal Governments, States and Territories, and 

local agencies to support research and innovative application of research. It 

is anticipated that the program would support approximately 25 agreements 

of varying sizes averaging about $80,000 each.

Funding Summary: 

Total new funding to support implementation of a National Landslide Hazard Mitigation 

Strategy as described herein is estimated to be $20 million annually:

- Expansion of the research, assessment, monitoring, public information, and 

response efforts by USGS scientists ($8 million annually)

- Establishment of a Cooperative Landslide Hazard Assessment and Mapping 

Program to increase State and local governments efforts to map and assess 

landslide hazards within their jurisdictions through competitive grants ($8 

million annually to be augmented with 30% matching funds by the States and 

local jurisdictions)

- Establishment of a Cooperative Federal Land Management Landslide Hazard 

Program to increase the National Park Service, U.S. Forest Service, Bureau of 

Land Management, and other such organizations capabilities to address landslide 

hazards under their jurisdictions ($2 million annually for work performed by 

USGS scientists on public lands)

- Establishment of a Partnerships for Landslide Hazard Loss Reduction Program 

to support research and implementation efforts by universities, local 

governments, and the private sector through competitive grants ($2 million 

annually)
30

3.5. Major Accomplishments and Products 

Full implementation of the National Landslide Hazards Mitigation Strategy would 

result in a number of major accomplishments and products over the first 10 years of

the program, including: 

- Reduced losses from landslides; 

- Reduced risk from future landslides; 

- Greater public awareness of landslide hazards and options for mitigating losses;

- Improved technology for landslide mitigation;

- Assessments and maps of landslide susceptibility in landslide-prone areas;

- Assessments and maps of other ground failure hazards in susceptible areas;

- Assessments and maps of landslide and ground-failure susceptibility on Federal 

Lands;

- Policies to encourage landslide mitigation by government, communities and the 

private sector;

- Robust national landslide hazards information clearinghouse system;

- Data bases of economic and environmental losses from landslides and other 

forms of ground failures nationwide;

- Guidelines and training materials for scientists, engineers, planners, decision 

makers;

- Curriculums and training materials for public awareness of landslide hazards;

- Real-time monitoring of critically hazardous active landslides nationwide;

- Coordinated landslide emergency response capability nationwide.

Progress in implementing the National Landslides Hazards Mitigation Strategy will 

be monitored by working groups established to coordinate and guide the Strategy. 

These groups will include representatives of Federal, State, and local governments 

and the private sector. Specific performance goals for the Strategy, including 

accomplishments and products, will come from a comprehensive review of national 

needs and priorities and will result in specific plans and schedules. In addition, 

progress in reducing losses will be monitored as part of Element 4 (pg 15), 

compilation and evaluation of losses from landslide hazards. 

.
31

Appendix A. Meetings with Stakeholders

Meetings were held during 1999 and 2000 with representatives of stakeholder 

organizations that have important roles in reducing landslide losses in the U.S. in order 

to obtain their input into a national strategy to mitigate landslide hazards. Meetings 

were held with State geologists, private consultants and university professors concerned 

with landslide hazards, and Federal, State and local government officials whose 

responsibilities include landslide hazard loss reduction. Many of their recommendations 

have been incorporated into the National Strategy either through input at meetings or 

subsequent reviews of this report. The following are lists of participants who attended 

each meeting.

Landslide Hazards Mitigation Stakeholder Meeting

State Geologists Meeting

Philadelphia, PA

January 16-17, 1999

Lee Allison State Geologist Kansas Geological Survey

John Beaulieu State Geologist Oregon Department Geology

and Mineral Industries

Tom Berg State Geologist Ohio Geological Survey

Vicki Cowart State Geologist Colorado Geological Survey

Jim Davis State Geologist California Department of 

Mines and Geology

Charles Gardner State Geologist North Carolina Geological 

Survey

Don Hoskins State Geologist Pennsylvania Geological 

Survey

John Kiefer Assistant State Geologist Kentucky Geological Survey

William Shilts State Geologist Illinois Geological Survey

Randy Updike USGS Golden, Colorado

Lynn Highland USGS Golden, Colorado

John Filson USGS Reston, Virginia
32

Landslide Hazards Mitigation Stakeholders Meeting

Private Sector Meeting

Albuquerque, New Mexico

February 23-24, 1999

Don Banks, Consultant, Vicksburg, Mississippi

Bill Cotton Cotton, Shires & Associates, Inc., Los Gatos, California

Bruce Clark Leighton & Associates, Inc., Irvine, California

Lloyd Cluff Pacific Gas & Electric, San Francisco, California

Richard Gray GAI Consultants, Inc., Monroeville, Pennsylvania

Jim Hamel Hamel Geotechnical Consultants, Monroeville, 

Pennsylvania

G.P. Jayaprakash NRC Transportation Research Board, Washington, D.C.

Jeff Keaton AGRA Earth and Environmental, Inc, Phoenix, Arizona

George Kiersch Kiersch Associates, Tucson, Arizona

George Mader Spangle Associates, Portola Valley, California

Ralph Peck Consultant, Albuquerque, New Mexico

Bill Roberds Golder Associates, Redmond, Washington

Roy Shelmon Consultant, Newport Beach, California

Rex Baum USGS, Golden, Colorado

Randy Updike USGS, Golden, Colorado

-----------------------------------------------------------------------------------

Landslide Hazards Mitigation Stakeholder Meeting

Academic Sector Meeting

Albuquerque, New Mexico

February 26-27, 1999

Ed Cording University of Illinois

Herbert Einstein Massachusetts Institute of Technology

Arvid Johnson Purdue University

Howard Kunreuther Wharton School, University of Pennsylvania

David Montgomery University of Washington

Rob Olshansky University of Illinois

Nick Sitar University of California

Keith Turner Colorado School of Mines

Erik VanMarcke Princeton University

Bob Watters MacKay School of Mines, University of Nevada

Bob Fleming USGS, Golden, Colorado

Randy Updike USGS, Golden, Colorado
33

Landslide Hazards Mitigation Strategy Summit Meeting

San Antonio, Texas

August 31 – September 1, 1999

David Applegate American Geological Institute

Rex Baum USGS, Golden, Colorado

Steven R. Bohlen USGS, Reston, Virginia

Bruce Clark Leighton & Associates

Timothy Cohn USGS, Reston, Virginia

Derek Cornforth Landslide Technology, Portland, Oregon

Vicki Cowart Colorado Geological Survey

Kim Davis California Department of Conservation

Anthony de Souza National Research Council

Robert Fakundiny New York Geological Survey

John Filson USGS, Reston, Virginia

John Grant NASA

Robert Hamilton National Research Council

Lynn Highland USGS, Golden, Colorado

G.P. Jayaprakash NRC Transportation Research Board

Arvid Johnson Purdue University

Jeff Keaton AGRA Earth & Environmental, Inc., Phoenix, 

Arizona

Pat Leahy USGS, Reston, Virginia

Lindsay McClelland National Park Service

Doug Morton USGS, Riverside, Calirornia

Robert Olshansky University of Illinois, Urbana/Champaign

John Pallister USGS, Reston, Virginia

William Roberds Golder Associates, Redmond, Washington

William Shilts Illinois State Geological Survey

Elliott Spiker USGS, Reston, Virginia

Randy Updike USGS, Golden, Colorado

Erik Van Marcke Princeton University

Tom Yorke USGS, Reston, Virginia

-------------------------------------------------------------------------------------

Landslide Hazards Mitigation Stakeholders Meeting

Land-Use Planners Meeting

Chicago, Illinois

February 17-18, 2000

Steven Briggs Cincinnati Planning Department

Paula Gori USGS, Reston, Virginia

James A Hecimovich American Planning Association

Lynn Highland USGS, Golden, Colorado

Sanjay Jeer American Planning Association

George Mader, AICP Spangle Associates, Portola Valley, California

Robert B. Olshansky, AICP University of Illinois – Urbana-Champaign

Jane Preuss, AICP GeoEngineers, Seattle, Washington

Daniel Sentz Pittsburgh Department of City Planning

Elliott Spiker USGS, Reston, Virginia
34

Appendix B.

Previous Reports and Sources of 

Landslide Hazards Information

The proposed National Landslide Hazards Mitigation Strategy incorporates many ideas 

and recommendations of previous studies and reports. These studies and reports should 

be referred to for more in-depth discussions of and insights into landslide hazard 

mitigation and research needs: 

- Goals, Strategies, Priorities and Tasks of a National Landslide Hazard Loss 

Reduction Program, (USGS, 1981, Open-File Report 81-987) sets forth goals and 

tasks for landslide studies, evaluating and mapping the hazard, disseminating 

information, and evaluating the use of the information. 

- Goals and Tasks of the Landslide Part of a Ground-Failure Hazards Reduction 

Program, (USGS Circular 880, 1982) describes a national program. 

- Feasibility of a Nationwide Program for the Identification and Delineation of 

Hazards from Mud flows and Other Landslides, (Campbell, Russell H et al, 1985, 

USGS Open-File Report 85-276) identifies the need for a national program.

- Reducing Losses from Landsliding in the United States, (Committee on Ground 

Failure Hazards, NRC, 1985, National Academy Press) recommends development 

of a national program and summarized the roles of government and the private 

sector in landslide mitigation nationwide.

- Landslide Classification for Identification of Mud Flows and other Landslides,

(Campbell, Russell H., et al, Chapter A in USGS Open File-Report 85-276, 1985) 

resulted from a joint study by the USGS and FEMA to evaluate the feasibility of 

delineating landslide hazards nationwide. 

- Landslides Investigation and Mitigation, Special Report 247 (Transportation 

Research Board, NRC, 1996, National Academy Press) provides a summary of the 

state-of-the-science of landslide hazard research, mapping and assessment in the 

U.S.

- National Mitigation Strategy – Partnerships for Building Safer Communities,

(FEMA, 1996), provides a framework for mitigation of all natural hazards in the 

U.S.

- The Impacts of Natural Disasters – A Framework for Loss Estimation, (Board on 

Natural Disasters, NRC, 1999, National Academy Press) recommends compilation 

of a comprehensive database on losses of natural disasters.

- Land Subsidence in the United States, (Galloway, D., Jones, D.R., and Ingebritsen, 

S.E., eds., 1999, USGS Circular 1182) explores the role of underground water in 

human-induced land subsidence through case histories.

- Disasters by Design: A reassessment of natural hazards in the United States, Dennis 

S. Mileti, 1999, Joseph Henry Press) provides an overview about what is known 

about managing natural hazard disasters, recovery and mitigation.
35

Appendix C.

Landslide Hazards and Other Ground Failures --

Causes and Types

Causes of Landslides

Landslide is a general term for a wide variety of downslope movements of earth 

materials that result in the perceptible downward and outward movement of soil, rock, 

and vegetation under the influence of gravity. The materials may move by falling, 

toppling, sliding, spreading, or flowing. Some landslides are rapid, occurring in 

seconds, whereas others may take hours, weeks, or even longer to develop.

Although landslides usually occur on steep slopes, they also can occur in areas of low 

relief. Landslides can occur as ground failure of river bluffs, cut-and-fill failures that 

may accompany highway and building excavations, collapse of mine-waste piles, and 

slope failures associated with quarries and open-pit mines. Underwater landslides 

usually involve areas of low relief and small slope gradients in lakes and reservoirs or in 

offshore marine settings.

Landslides can be triggered by both natural changes in the environment and human 

activities. Inherent weaknesses in the rock or soil often combine with one or more 

triggering events, such as heavy rain, snowmelt, and changes in groundwater level, or 

seismic or volcanic activity. Long term climate change may result in an increase in 

precipitation and ground saturation and a rise in goundwater level, reducing the shear 

strength and increasing the weight of the soil. Erosion may remove the toe and lateral 

slope support of potential landslides. Storms and sea level rise often exacerbate coastal 

erosion and landslides. Earthquakes and volcanoes often trigger landslides.

Human activities triggering landslides are usually associated with construction and 

changes in slope and surface water and groundwater levels. Changes in irrigation, 

runoff and drainage can increase erosion and change groundwater levels and ground 

saturation. 
36

Types of Landslides

The common types of landslides are described below. These definitions are based 

mainly on the work of Varnes (Varnes, D.J., 1978. “Slope Movement Types and 

Special Report 176: Landslides: Analysis and Control (R.L. Schuster and 

R.J. Krizek, eds.), TRB National Research Council, Washington, D.C., pp. 12-13.).

Falls - abrupt movements of materials that become detached from steep slopes or cliffs, 

moving by free-fall, bouncing, and rolling, including: 

Topple - a block of rock that tilts or rotates forward and falling, bouncing or 

rolling down the slope.

Slides - Many types of mass movement are included in the general term 

“landslide”. The two major types of landslides are rotational slides and 

translational landslides:

Rotational landslide - the surface of rupture is curved concavely upward 

(spoon shaped) and the slide movement is more or less rotational. A “slump” is 

an example of a small rotational landslide.

Translational landslide - the mass of soil and rock moves out or down and 

outward with little rotational movement or backward tilting. Translational 

landslide material may range from loose unconsolidated soils to extensive slabs 

of rock and may progress over great distances if conditions are right. 

Lateral Spreads – often occur on very gentle slopes and result in nearly horizontal 

movement of earth materials. Lateral spreads usually are caused by liquefaction, where 

saturated sediments (usually sands and silts) are transformed from a solid into a 

liquefied state, usually triggered by earthquake.

Flows - Many types of mass movement are included in the general term “flow”, 

including: 

Creep - the slow, steady down slope movement of soil or rock, often indicated 

by curved tree trunks, bent fences or retaining walls, tilted poles or fences.

Debris flow - a rapid mass movement in which loose soils, rocks, and organic 

matter combine with entrained air and water to form a slurry that then flows 

downslope, usually associated with steep gullies.

Debris avalanche - a variety of very rapid to extremely rapid debris flow.

Mudflow – a rapidly flowing mass of wet material that contains at least 50 

percent sand-, silt-, and clay-sized particles.

Lahar - a mudflow or debris flow that originates on the slope of a volcano, 

usually triggered by heavy rainfall eroding volcanic deposits, sudden melting of 

snow and ice due to heat from volcanic vents, or by the breakout of water from 

glaciers, crater lakes, or lakes dammed by volcanic eruptions.
37

Submarine and subaqueous landslides – include rotational and translational landslide, 

debris flows and mudflows, and sand and silt liquefaction flows that occur principally or 

totally underwater in lakes and reservoirs, or in coastal and offshore marine areas. The 

failure of underwater slopes may result from rapid sedimentation, methane gas in 

sediments, storm waves, current scour, or earthquake stresses. Subaqueous landslides 

pose problems for offshore and river engineering, jetties, piers, levees, offshore 

platforms and facilities, and pipelines and telecommunications cables.

Subsidence - Another major form of ground failure, land subsidence, affects more than 

17,000 square miles in 45 States. Land subsidence, a gradual settling or subsidence of 

the earth’s surface, is an often-overlooked environmental consequence of land- and 

water-use practices. More than 80% of the identified subsidence in the Nation is a 

consequence of ground water withdrawal, and the increasing development of land and 

water resources threaten to exacerbate existing land subsidence problems and initiate 

new ones (Land Subsidence in the United States, U.S. Geological Survey Circular 1182, 

1999, edited by D. Galloway, D. R. Jones, and S.E. Ingebritsen).

Swelling Soils – Another major form of ground failure, the swelling or rising of the 

ground surface, is a phenomenon frequently encountered in arid regions in soil 

containing montmorillonite clay. Montmorillonite clay particles can absorb large 

quantities of water, and in so doing will expand resulting in an uplift at the ground 

surface. Soils are usually not homogeneous, resulting in differential absorption and 

differential movements over a site. If the presence of the clay is unknown before 

development, the swelling may develop after a house is completed and residents begin 

watering gardens or using septic tanks, resulting in damage to structures and breaks in 

connecting utilities.

Permafrost – Ground failure related to frost action and permafrost are a problem in 

northern climates, especially in Alaska. Changes in climate and a significant warming 

in Alaska is resulting in widespread thawing of permafrost, often resulting in a settling 

of the soil. 
38

Appendix D.

Landslide Hazards Mitigation Strategies

Over the past few decades, an array of techniques and practices has evolved to reduce 

and cope with losses from landslide hazards. Careful development can reduce losses by 

avoiding the hazards or by reducing the damage potential. Landslide risk can be reduced 

by five approaches used individually or in combination to reduce or eliminate losses.

Restricting Development in Landslide-Prone Areas – Land use planning is one of the 

most effective and economical ways to reduce landslide losses by avoiding the hazard 

and minimizing the risk. This is accomplished by removing or converting existing 

development or discouraging or regulating new development in unstable areas. In the 

United States, restrictions on land use generally are imposed and enforced by local 

governments by means of land use zoning districts and regulations. Implementation of 

avoidance procedures has met with mixed success. In California, extensive restriction of 

development in landslide-prone areas has been effective in reducing landslide losses. 

For example, in San Mateo County, California, since 1975 the density of development 

has been limited in landslide-susceptible areas. However, in many other states, there 

are no widely accepted procedures or regulations for landslides (NRC Committee on 

Ground Failure Hazards 1985).

Codes for Excavation, Construction, and Grading Codes - Excavation, construction, 

and grading codes have been developed for construction in landslide-prone areas. There 

is no nationwide uniform code to ensure standardization in the United States; instead, 

State and local government agencies apply design and construction criteria that fit their 

specific needs. The city of Los Angeles has been effective in using excavation and 

grading codes as deterrents to landslide activity and damage on hillside area. The 

Federal government has developed codes for use on federal projects. Federal standards 

for excavation and grading often are used by other organizations in both the public and 

private sectors (NRC Committee on Ground Failure Hazards, 1985). 

Protecting Existing Development - Control of surface water and groundwater drainage 

is the most widely used and generally the most successful slope-stabilization method 

(Committee on Ground Failure Hazards 1985). Stability of a slope can be increased by 

removing all or part of a landslide mass, or by adding earth buttresses placed at the toes

of potential slope failures. Restraining walls, piles, caissons, or rock anchors, are 

commonly used to prevent or control slope movement. In most cases, combinations of 

these measures are used. 

Monitoring and Warning Systems - Monitoring and warning systems are utilized to 

protect lives and property, not to prevent landslides. However, these systems often provide warning of slope movement in time to allow the construction of physical measures 

that will reduce the immediate or long-term hazard. Site-specific monitoring techniques 

include field observation and the use of various ground motion instruments, trip wires, 

radar, laser beams, and vibration meters. Data from these devices can be telemetered for 

real-time warning. 
39

Development of regional real-time landslide warning systems is one of the more 

significant areas of landslide research. One such system was successfully developed for 

the San Francisco Bay region, California, by the USGS in cooperation with NOAA and 

the National Weather Service. The system is based on relations between rainfall 

intensity and duration and thresholds for landslide initiation, geologic determination of 

areas susceptible to landslides, real-time monitoring of a regional network of rain 

gauges, and National Weather Service precipitation forecasts. 

Landslide insurance and compensation for losses - Landslide insurance would be a 

logical means to provide compensation and incentive to avoid or mitigate the hazard. 

Landslide insurance coverage could be made a requirement for mortgage loans. 

Controls on building, development, and property maintenance would need to accompany 

the mandatory insurance. Insurance and appropriate government intervention can work 

together, each complementing the other in reducing losses and compensating victims. 

However, landslide insurance is essentially absent across the Nation, except for mine 

subsidence coverage in eight states and some coverage for landslides due to earthquakes, 

if earthquake insurance is purchased, and minimal coverage for mudslides by the 

National Flood Insurance Program (FEMA). 

The primary reason insurance companies, for the most part, do not offer landslide 

insurance is the potential for adverse selection by the insured population. If insurance 

for landslides was made available, only those individuals in the most hazardous areas 

would buy the insurance, which would lead to very high premiums nearly equal to the 

value of the property. An alternative to private sector insurance would be a public 

insurance program, possibly modeled after the National Flood Insurance Program. 

Incentives to mitigate landslide hazards must also accompany insurance coverage, much 

like fire-preventative incentives appear on current homeowners insurance polices.

A major obstacle to implementing some form of landslide insurance is the lack of 

technical information, maps, and assessments of landslide hazards. A joint study in 

1985 by the USGS and FEMA examined the feasibility of a nationwide program for 

identification and delineation of hazards from mud flows and other landslides. That 

study concluded that landslide hazards could be evaluated and mapped nationwide 

through a systematic sequence of studies, ranging from regional to local studies in 

progressively more detail. The comprehensiveness and accuracy with which landslide 

hazards would be delineated could be balanced against the costs of the program. 
40

Appendix E.

Landslide Hazards Maps and Risk Assessments

Public and private organizations need both sound economic and scientific basis for 

making decisions about reducing landslide-related losses. Quantitative risk assessment 

is a widely used tool for making such decisions as it provides estimates of the probable 

costs of losses and provides various options for reducing the losses. Such assessments 

can be either site specific or regional. 

A risk assessment is based on the probability of the hazard and an analysis of all 

possible consequences (property damage, casualties, and loss of service). Typically 

private consultants with expertise in risk assessment, in cooperation with the other 

partners or landowners, conduct risk assessments based on the results of the landslide 

susceptibility and probability studies. In many cases, private users such as insurance 

companies perform their own risk assessments from the probability data. 

Regional landslide risk assessments can be accomplished through public and private 

partnerships involving the USGS, State geological surveys, local governments, and 

private consultants. An example would be a partnership in which the USGS and the 

State geological surveys cooperate to collect the basic geologic map data, and landslide 

inventory data. Local governments would provide access to their detailed topographic 

databases and records of landslide occurrence. The USGS would analyze the geologic, 

topographic, landslide and other data to determine landslide susceptibility and 

probability. 

Federal, State, and local government agencies, banks, and private landowners can use 

the probability estimates and risk assessments to help identify areas where expected 

landslide losses are costly enough to justify remedial efforts or avoidance. More 

detailed studies can then be conducted in these areas to determine the optimal strategy 

for reducing landslide-related losses. 

Types of landslide hazards maps: 

A landslide inventory map shows the locations and outlines of landslides. A landslide 

inventory is a data set that may represent a single event or multiple events. Small-scale 

maps may show only landslide locations whereas large-scale maps may distinguish 

landslide sources from deposits and classify different kinds of landslides and show other 

pertinent data. 

A landslide susceptibility map ranks slope stability of an area into categories that range 

from stable to unstable. Susceptibility maps show where landslides may form. Many 

susceptibility maps use a color scheme that relates warm colors (red, orange, and 

yellow) to unstable and marginally unstable areas and cool colors (blue and green) to 

more stable areas. 

A landslide hazard map indicates the annual probability (likelihood) of landslides 

occurring throughout an area. An ideal landslide hazard map shows not only the 

chances that a landslide may form at a particular place, but also the chances that a 

landslide from farther upslope may strike that place. 

A landslide risk map shows the expected annual cost of landslide damage throughout 

an area. Risk maps combine the probability information from a landslide hazard map 

with an analysis of all possible consequences (property damage, casualties, and loss of 

service). 
41

Maps showing initial steps of a regional landslide risk assessment for an area in Seattle, 

Washington. Figure A. Landslide inventory map overlain on a topographic base map, showing 

the locations and outlines of landslides (USGS and Shannon and Wilson, Inc.). Figure B. 

Landslide susceptibility map (USGS, Colorado School of Mines). 

A. Landslide inventory map. B. Landslide susceptibility map.
42

Appendix F.

Federal, State, and Local Agencies and Programs 

Many different Federal, State, and local agencies, academia, as well as private 

companies, are involved in landslide research and mitigation in the United States; 

however, currently there is little interagency coordination of landslide hazard mitigation 

activities. Because the need for information spans the interests of many public and 

private organizations, the National Landslide Hazards Mitigation Strategy offers new 

opportunities for mutually advantageous partnerships relating to hazard assessments, 

monitoring, and emergency response and recovery. Each level of government - Federal, 

State, and local, nongovernmental organizations, businesses, and individuals have some 

responsibility for mitigating, responding to, and recovering from landslide hazards. 

Federal Agencies

The Federal role in hazard reduction has its origin in the Organic Act of 1879 that 

created the USGS. More recent legislation addressing the Federal role in landslide 

hazards include the Dam Inspection Act of 1972, which stipulated responsibilities for 

landslide hazards affecting the safety of dams and reservoirs, and the 1974 Disaster 

Relief Act and subsequent reauthorizations, which gave the USGS responsibility to issue 

timely disaster warning of potential landslides. 

The USGS Landslide Hazard Program is the only Congressionally authorized program 

dedicated to landslide hazards. The USGS National Landslide Information Center is a 

prototype clearinghouse for issuing advisories, press statements, and other information 

about landslides. The USGS has developed expertise in research, assessment, and 

mapping of landslide hazards and provides technical assistance during disaster response. 

The National Science Foundation (NSF) and the NASA fund landslide hazard research 

in the academic community. The National Oceanic and Atmospheric Administration, 

National Weather Service (NWS) personnel provide weather forecasts and assist in 

emergency response activities. Other Federal agencies, including the U.S. Army Corps 

of Engineers, Bureau of Land Management, U.S. Forest Service, National Park Service, 

Office of Surface Mining Reclamation and Enforcement, Department of Transportation 

(especially Federal Highway Administration), and Bureau of Reclamation have 

landslide hazard experts and activities in relation to lands and infrastructure under their 

jurisdiction.

The Federal Emergency Management Agency (FEMA) is responsible for emergency 

management and long-term mitigation of natural hazards including landslides. FEMA is 

the Federal coordinating agency for emergency response, disaster relief funding, and 

hazard mitigation efforts. The Federal Insurance Administration, a part of FEMA, 

provides insurance coverage for flood damages, including “mudslides.” However 

implementation has been difficult because of the absence of an accepted technical 

definition of a “mudslide” and an accepted methodology for delineating mudslide hazard 

areas. Landslides other than mudslides are not insured under this program. 
43

State and Local Government Agencies

While the Federal government plays a lead role in funding and conducting landslide 

research, in developing landslide mapping and monitoring techniques, and in landslide 

hazard management on Federal lands, the reduction of landslide losses on other lands is 

primarily a State and local responsibility. A number of State agencies, commissions and 

councils have responsibility for landslide hazards, including those with oversight of 

natural resources, transportation, geology, hazards, emergency services, and land-use 

issues. 

States vary in their approaches to landslide hazards. Some States produce inventories of 

landslides and maps of landslide-prone areas for use by local government, business, and 

the public. However, landslide mapping has been done without widely accepted 

standards of accuracy, scale, and format. Some States monitor landslide-prone areas and 

provide expertise for response and recovery activities. Several States conduct research 

on landslide problems in their State, and a few States have regulatory authority.

The reduction of landslide losses through land-use planning and application of building 

and grading codes is the function of local government. Localities throughout the nation 

differ in their regulatory authority and approach to reducing losses from landslide 

hazards. Local governments have the responsibility to issue warnings of imminent 

landslides and manage emergency operations after a landslide. FEMA may become 

involved after a Presidential declared disaster. 

Landslide hazards have traditionally occupied a relatively modest place in public policy, 

embodied in zoning, legal liability, insurance, building codes, land-use practices, and 

environmental quality. Maps showing historic landslides and areas susceptible to 

landslides have been used only sporadically for zoning and for purposes of real-estate 

disclosure. Building codes have been drafted for some localities to set minimum 

standards for construction on unstable slopes. Federal and State forestry practices in 

many localities include attention to landslide hazards. Building setbacks from coastal or 

riverine bluffs have been established in some areas on the basis of projected failure by 

landsliding. However, broad systematic policy approaches to landslide and other ground 

failure hazards are rare, and most areas of the Nation lack the most fundamental 

technical information or policies to cope with their hazards.

Private and Academic Sectors

Private sector geologists, engineers, and building professionals are often involved in the 

identification and implementation of landslide reduction measures in building design 

and planning. University researchers conduct research on landslide processes and 

development of monitoring and mitigation technologies and methods. These 

professionals provide advice to business and industry for loan, insurance, and 

investment decisions. Professional societies such as the American Society of Civil 

Engineers, the Association of Engineering Geologists, and the American Planning 

Association serve as conduits of information from researchers to practitioners and 

practitioners to researchers. Professional societies are generally the source of model 

codes, handbooks, and professional training for their membership, who in turn use the 

information to improve the state-of-knowledge of landslide loss reduction in the private 

and public sectors.
44

Federal Agency Landslide Hazards Activities

The following Federal agencies provided descriptions of their landslide hazards 

activities.

Department of the Interior - U. S. Geological Survey

The USGS directly or indirectly funds and maintains landslide hazard expertise in 

several of its programs. These programs direct research and assessment of landslides, 

debris flows, and lahars caused by storms, earthquakes and volcanoes, submarine 

landslides, riverine and coastal erosion. The following is an explanation of USGS 

landslide hazard activities:

Landslide Hazards Program - The Landslide Hazards Program supports hazard 

investigations and assessments, research on monitoring and forecasting landslides, 

responding to landslide emergencies and operating the National Landslide Information 

Center in Golden, Colorado. The Program supports research and assessment that can 

lead to implementation of mitigation strategies for Federal, State, and local landmanagement and emergency-response agencies, as well as providing a basis for land-use 

planning, emergency planning and private decision-making including insurance and 

financial incentives. Much of the current work is being conducted in the Pacific 

Northwest, California, and the Blue Ridge Mountains in the East.

The program supports research on landslide processes and development and deployment 

of instrumentation to monitor active landslides to improve landslide forecasting. The 

majority of the real-time monitoring activities are taking place in Washington, 

California, New Mexico, and Colorado. The Program also responds, on request, to 

national and international landslide disasters. In this capacity, the Program assists 

Federal, State, and local agencies to evaluate landslide hazards and recommends 

mitigation strategies.

The National Landslide Information Center maintains landslide databases, 

communicates with the public and press about ongoing landslide emergencies, and 

provides information to the public and organizations through fact sheets, a dedicated 

Internet website (http://landslides.usgs.gov), books and reports.

Earthquake Hazards Program - The USGS National Earthquake Hazards Reduction 

Program supports USGS studies and external, cooperative studies of landslides caused 

by earthquakes, including liquefaction investigations in California. It also supports 

seismic instrumentation of landslide sites.

Volcano Hazards Program - The Volcano Hazards Program funds debris-flow research 

at the Cascades Volcano Observatory. The research includes field investigations at 

Mount St. Helens and Mount Rainier, Washington, and an experimental debris-flow 

flume in the Willamette National Forest, Oregon. The Volcano Disaster Assessment 

Program conducts lahar investigations internationally.

Coastal and Marine Geology Program - The Coastal and Marine Geology Program 

focuses on coastal and submarine landslide studies. The areas of investigations include 

California, Washington, Alaska, Hawaii, and Lake Michigan. The Program also 

conducts subsidence studies in Louisiana.
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National Geologic Cooperative Mapping Program - The National Geologic Cooperative 

Mapping Program supports comprehensive geologic mapping as a basis for landslide 

hazard assessment through the matching fund STATEMAP grants program. 

Earth Surface Dynamics Program – The Earth Surface Dynamics Program supports 

research on landslide processes and climate history in the Blue Ridge in the eastern U.S.

Water Resources Division Programs - The Water Resources Division conducts research 

on landslides, debris flows, subsidence, and riverine and coastal erosion. Research is 

also supported through its District Offices in Hawaii, Puerto Rico, and other States as 

landslides occur. 

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Federal Emergency Management Agency

The Federal Emergency Management Agency (FEMA) has many roles in landslide 

hazard loss reduction. FEMA has responsibilities in emergency response, disaster 

assistance, and promotion of landslide hazard mitigation.

FEMA coordinates the Federal government’s response to disasters such as earthquakes, 

hurricanes, and volcanoes that include landslides through the Federal Response Plan. 

The agency provides financial assistance to State and local governments for repair of 

public facilities damaged during these disasters including replacement of lost fill and 

construction of fill retaining devices such as gabions, rock toes, etc. Following 

disasters, the agency also supports installation of mitigation measures such as installing 

drainage ditches to direct flow away from the landslide areas. 

FEMA provides relief to individuals damaged by mudslides who are covered by the 

National Flood Insurance program; however, the distinctions that the agency makes 

between landslides and mudslides have been a source of controversy, as the agency 

provides only limited damage coverage. Also encouraging mitigation measures in 

tandem with insurance coverage, which is a cornerstone of the flood insurance program, 

has been impossible because to date, there are no maps that delineate mudslide zones 

and no standards governing development in mudslide-prone areas. 

FEMA promotes landslide hazard mitigation by developing State and national 

guidebooks for landslide loss reduction including a prototype mitigation plan that can be 

incorporated into existing hazard mitigation plans. Through FEMA’s Project Impact, 

the agency is encouraging local jurisdictions to implement mitigation programs that 

reduce among other hazards, landslides. In the Seattle Project Impact, landslide hazard 

mapping is a major part of the community’s effort. 

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Department of the Interior - National Park Service

Many national parks are geologically active, exposing park visitors, staff, and 

infrastructure to geologic hazards. Landslides, including slope failures, mudflows, and 

rockfalls impact parks by causing deaths and injuries, closing roads and trails, and 

damaging park infastructure. Recent examples include several rockfalls in Yosemite 

Valley, each with one fatality; damaging landslides in Shenandoah National Park 

triggered by torrential rains; repeated slope failures fed by artificial aquifers at 
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Hagerman Fossil Beds National Monument; landslides that closed roads in Zion and 

Yellowstone National Parks; and the threat of large debris flows at Mt. Rainier. USGS 

scientists have provided insights essential to effective response to landslides hazards at 

these and other national parks.

Because it is a natural process, landslide activity is generally allowed to proceed 

unimpeded in national parks unless safety is a concern. However, where people have 

destabilized the landscape, such as through logging, mining, and road-building, 

disturbed lands are restored where practical to their pre-disturbance condition.

To reduce risk from landslides and other geologic hazards, park planners must 

incorporate information from hazard assessments and maps into decisions about 

appropriate sites for facilities such as campgrounds, visitor centers, and concession 

areas. Planners face difficult choices as they attempt to balance risks from different 

hazards, such as floods and rockfalls in confined valleys, and as they work to provide 

safe public access to popular but potentially hazardous areas. When a landslide or other 

hazard occurs, parks must quickly rescue people, stabilize structures, and clear debris 

from roads and other public areas. Critical next steps are to work with experts to assess 

the nature and extent of the event and the risk and recurrence. Short-term studies are 

required to help managers decide whether and when to reopen impacted areas, then 

more detailed research is often needed to inform decisions about future use of the 

immediately affected area and other areas that may face similar hazards.

Park interpretive programs inform visitors about key resources and issues, offering the 

opportunity to help the public to better understand geologic hazards. Interpreters 

communicate directly with visitors through programs such as nature walks and campfire 

presentations, as well as through the content of exhibits in visitor centers, and in some 

cases through books and videos sold by park cooperating associations and 

concessionaires. The National Park Service is increasingly reaching out to a broader 

audience, many of whom may not have the opportunity to visit parks, through 

innovative methods including school programs and websites. Interpreters work in 

partnership with the scientific community to ensure that complex information can be 

conveyed accurately, and in a form that is comprehensible and relevant to nonspecialists.

These and other park programs would welcome additional help to assess landslide 

hazards in parks, provide input to park planning so that infrastructure can be located 

away from zones of greatest landslide risk, respond quickly after significant landslide 

events, and improve communication with the public.

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Department of the Interior - Office of Surface Mining 

Reclamation and Enforcement

Office of Surface Mining’s (OSM) role in landslide mitigation is confined to those 

landslides that are related to past coal mining activity as authorized by the Surface 

Mining Control and Reclamation Act. A coal mining technique in the Appalachians 

involving mountaintop removal and valley filling is monitored by OSM to prevent 

serious landslides. Most abandoned mine land landslide areas are reclaimed through 

State or Indian tribe abandoned mine land programs, funded with OSM grants. Office 

of Surface Mining, through its Federal Reclamation Program has responsibility in those 

State/Tribes that do not have approved programs.
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When there is an immediate danger to the occupants of dwellings caused by a landslide, 

abatement actions are taken immediately through OSM or State emergency programs. 

Otherwise, landslide problem areas that endanger human health, safety and general 

welfare are assigned priorities and mitigation actions are taken based on the highest 

priority.

Reclamation records, maintained in OSM’s Abandoned Mine Land Inventory System, 

indicate that OSM and the States/Tribes have completed reclamation on 3,367 acres of 

dangerous slides at a cost of $125.25 million. Also, 651 acres are designated as a high 

priority and have been funded, but not yet reported as completed, at $30.69 million. An 

additional 2,276 acres, with an estimated cost of $73.77 million, are unfunded. 

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Department of Agriculture - Forest Service

The U.S. Department of Agriculture Forest Service is a land management agency with 

responsibility for natural resources on National Forests. Most of the National Forest 

system lands are located in the mountainous areas of the western United States including 

large parts of Alaska. The road system on National Forests is of a comparable size to 

many State road systems. As a consequence, designing low volume roads to avoid 

landslide problems and repairing the damage to them from landslides is a major task. 

Additionally, the location of National Forests means Interstate and major State 

highways, railroad lines, oil and gas pipelines, and electric transmission corridors pass 

through them. It is necessary to address landslide hazards in the environmental 

assessment of these projects and where specific landslide impacts occur along existing 

ones. 

National Forests generally occupy the headwaters of major rivers, which places a 

premium on watershed management. This is especially true for those watersheds where 

anadromous fisheries and significant inland fisheries are present. Increased landslide 

activity can produce sediment loads that degrade water quality and impact fisheries 

habitat. Landslide hazard can be a more localized, but equally important, problem on 

National Forests where development of large ski resorts, mines, or hydroelectric 

facilities take place. Major wildfires may sufficiently denude watershed and lead to 

short-term landslide activity. National forests, especially those having developed 

private in-holdings and adjacent urban areas, must address the potential for loss of life 

and damage from debris flows initiated by precipitation events on burned watersheds.

A primary landslide hazard activity conducted by Forest Service personnel is providing 

evaluations of landslide hazard potential in environmental assessments or in review of 

environmental assessments prepared by forestry project proponents. Environmental or 

engineering geologists, as one of their primary duties, minerals geologists, as a related 

duty, or other earth scientists, where geologists are unavailable, carry out these 

evaluations. Engineering geologists and geotechnical engineers carry out environmental 

assessments and participate in designs to address landslide hazard to system roads.

Another activity is assessing damage from landslides following major natural disasters. 

The most formalized of these assessments is the Burned Area Emergency Rehabilitation 

procedure instituted during major wildfires. This activity also includes participating in 

development of stabilization and restoration projects to counter this damage.
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A national geographic information system network of National Forest lands and a data 

base that includes landslide information is under development. Both existing USGS and 

State survey information and mapping by Forest Service geologists generate the 

landslide hazard information for this GIS system. The Research Branch of the Forest 

Service has contributed many studies that improve our understanding of landslide hazard 

relative to specific forest management activities.

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Department of Commerce –

National Oceanic and Atmospheric Administration

The National Oceanic and Atmospheric Administration, National Weather Service 

(NWS) is involved in landslide mitigation through its role in the Federal Response Plan 

and its mission of providing services for the protection of life and property.

The National Weather Service works with other Federal, State, and local agencies by 

providing forecasts of hydrologic and meteorological conditions for landslide forecasts 

and mitigation efforts. This assistance may include on-scene meteorological personnel 

to assist in emergency response activities at landslides. NOAA Weather Radio and 

other NWS dissemination systems broadcast “Civil Emergency Messages” concerning 

landslide warnings and response and recovery efforts at the request of local, State, and 

Federal emergency management officials.

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Department of Defense – U.S. Army Corps of Engineers

As the premier full spectrum engineering organization, the missions of the Corps of 

Engineers include planning, design, building, and operating water resources and civil 

projects in the areas of flood control, navigation, environmental quality, coastal 

protection, and disaster response as well as the design and construction of facilities for 

the Army, Air Force, and other federal agencies. In performance of this broad mission, 

the Corps has addressed a full range of technical challenges associated with landslides 

and ground failure. Corps engineering geologists, geotechnical engineers, and 

geophysicists have been involved in the assessment, monitoring and analysis, and 

mitigation of landslides in a wide range of settings at locations around the world as well 

as basic and applied research on topics directly related to the analysis and mitigation of 

landslides and ground failures.

Landslide assessment activities by Corps scientists and engineers have included 

investigations of landslides of various mechanisms and scales along navigable 

waterways such as the Mississippi and Ohio Rivers which result in serious navigation 

hazards and threatening or loss of flood protection works. Landslides also play an 

important role in the erosion of the Nation’s shoreline: the protection of shoreline is a 

major responsibility of the Corps. Many Corps dam site investigations have involved the 

identification and assessment of past and potential landslides.

Corps engineering geologists, geotechnical engineers, and geophysicists have been 

involved in the monitoring of active landslides and ground failure in both natural and 

engineered soils and earth materials. Monitoring of landslides have focused on the 

identification of the temporal and spatial variability of earth movements and the 

identification of causal factors. Monitoring data have been used along with detailed site 
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information to analyze the stability of the landslide in terms of the initial movements, 

present conditions, and conditions after mitigation actions.

As an engineering agency, the Corps has a significant role in the planning, design, and 

construction of landslide mitigation measures associated with the protection of its civil 

and military projects. Specific methods for reducing landslide hazards and increasing 

slope stability have been developed and implemented by Corps engineers at sites around 

the world. The Corps’ critical and efficient flow of responsibility and results in 

landslide projects through the process of initial engineering geological investigation, 

engineering analysis, remedial design, implementation, construction, and post project 

monitoring is of particular value to the Nation and the international community.

The Corps has an important national mission in disaster response. This mission has 

involved the Corps in responding to landslides, especially as a result of floods, 

hurricanes, volcanic eruptions, and earthquakes. In assistance to FEMA, Corps 

personnel have provided emergency assessments and immediate mitigation of past and 

potential landslides. The Corps role in international disaster response has also become a 

major focus of landslide engineering. Recent landslide assessments, analysis, and 

mitigation efforts have been conducted in Venezuela, Honduras, Nicaragua, Colombia, 

Peru, Haiti, Puerto Rico, South Korea, and the Phillipines.

Research at the Corps Engineering Research and Development Center includes the 

development and testing of analytical tools and assessment methods and approaches for 

landslide mitigation. Basic research in soil and rock mechanics, geomorphology, 

hydrogeology, remote sensing, geophysics, and engineering geology has resulted in 

advancements in the understanding of the causative factors and mechanics of landslides 

and ground failures.