U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2011–3008

January 2011

N

How communities 

use hazard-prone 

land influences 

their vulnerability 

to future extreme 

events, such as 

volcanic mudflow 

(lahar) hazards 

associated with 

volcanoes. This 

photograph shows 

an area at risk from 

lahars from Mount 

Rainer, Washington. 

(USGS photo by 

Nathan Wood.)

RESEARCH AT THE USGS WESTERN GEOGRAPHIC SCIENCE CENTER

atural hazards threaten the 

safety and economic wellbeing of communities. These hazards 

include sudden-onset hazards, 

such as earthquakes, and slowly 

emerging, chronic hazards, such 

as those associated with climate 

change. To help public officials, 

emergency and other managers, 

the business community, and atrisk individuals reduce the risks 

posed by such hazards, the USGS 

Western Geographic Science 

Center is developing new ways to 

assess and communicate societal 

risk and resilience to catastrophic 

and chronic natural hazards.

The United States faces multiple natural 

hazards that threaten its safety, security, 

economic wellbeing, and natural resources. To balance near-term economic interests with long-term sustainability goals, 

as well as prepare for and recover from 

disasters, public officials, emergency and 

other managers, businesses, and at-risk 

individuals need a clear understanding of 

both societal risk from various threats and 

strategies to increase resilience. 

Societal risk and resilience to natural 

hazards are complex phenomena, involving the exposure, sensitivity, and adaptive 

capacity of human-environmental systems. 

These aspects of vulnerability are a function of (1) existing patterns of land use 

and land cover, (2) current socioeconomic 

conditions, (3) likely patterns of future 

land use, and (4) current efforts to mitigate, adapt to, or prepare for future events 

or conditions. 

 The U.S. Geological Survey (USGS) 

Western Geographic Science Center 

(WGSC) and the USGS Geographic Analysis and Monitoring (GAM) Program are 

committed to improving the Nation’s understanding of where and how it is vulnerable to natural hazards, what options exist 

for reducing unacceptable risks, and how 

to effectively respond so that recovery is 

rapid when catastrophes occur. Communities can use this information to reduce the 

impacts on quality of life and resources 

from future disasters.

Benefits of Understanding Risk

• Focuses public attention on controllable societal consequences of events 

instead of on uncontrollable natural 

processes;

• Identifies regions or areas that may 

warrant new risk-adaptation strategies, 

preparedness plans, public education, 

or land-use changes;

• Serves as baseline information for 

response efforts; and

• Highlights where additional hazard, 

risk, or mitigation assessments may be 

needed or improved. 

Risk

Natural Hazard Vulnerable System

Potential catastrophic 

and chronic events

Past recurrence intervals

Future probability

Speed of onset

Magnitude

Duration

Spatial extent

Exposure, sensitivity 

and adaptive capacity of:

Population

Economy

Land use and development

Infrastructure and facilities

Cultural assets

Ecosystem goods and services

Ability, resources, and will to:

Mitigate

Prepare

Respond

Recover

Understanding Risk and Resilience to Natural Hazards

Risk is not only a function of exposure to natural processes that can impact society but also a 

function of the choices we make as we inhabit a dynamic Earth. Impacts of events directly relate 

to human decisions and policies made before, during, and after a catastrophic event. 
Nathan Wood

Edited by James W. Hendley II

Graphics and layout by Judy Weathers

For more information, contact:

Nathan Wood U.S. Geological Survey 1300 SE Cardinal Court, Bldg. 10, Suite 100 Vancouver, WA 98683

 Tel. (360) 993-8951 nwood@usgs.gov http://geography.wr.usgs.gov/ http://geography.wr.usgs.gov/science/ vulnerability/

This Fact Sheet and any updates to it are available online 

at 

http://pubs.usgs.gov/fs/2011/3008/

WGSC Approaches to Understanding and Communicating Risk to Natural Hazards

Variations in community exposure and 

potential losses from hazards are summarized in terms of land cover, populations, 

economic assets, and critical infrastructure. This image shows various types of 

land cover in a tsunami-hazard zone 

 and helps

Modeling efforts that leverage geospatial 

data have addressed pedestrian evacuations, demographic sensitivity, economicloss estimation, and the evaluation of alternative mitigation strategies. This image 

shows hotspots of relative demographic 

N

Pacific

Ocean

Type of land cover

0.5 mi

Bare land and beach

Forest

Wetland

Grassland and open space

High-intensity developed

Low-intensity developed

Medium-intensity developed

Potential extent of tsunami 

inundation

Type of land cover

Pacific

Ocean

0.5 mi

N

Relative vulnerability 

 Low

Medium

 High

Potential extent of 

tsunami inundation

 officials

 pinpoint

 developed land. 

Geospatial and Economic Modeling

posure to tsunamis. Community workshops 

have been held to discuss vulnerability and 

post-disaster recovery from tsunamis. In cooperation with Clackamas County, WGSC 

scientists are examining population exposure and adaptive capacity to hazards associated with Mount Hood volcano. Working 

with Oregon State University and State 

agencies, WGSC is also examining vulnerability to coastal-erosion hazards enhanced 

by changing climatic conditions.

California

As part of the USGS Multi-Hazard Demonstration Project, WGSC has led efforts to 

characterize the social and economic consequences of a magnitude 7.8 earthquake 

scenario in southern California (http://

pubs.usgs.gov/of/2008/1150/), an extreme 

winter-storm scenario for California (http://

pubs.usgs.gov/of/2010/1312), and a tsunami scenario affecting southern California 

ports. Expertise in decision analysis is being applied to wildfire risk. These efforts 

include broad cooperation across governmental agencies and workshops with scientists, emergency managers, and community 

leaders and other stakeholders to develop 

estimates for infrastructure damages, agricultural damages, lifeline service restoration, and business interruption losses.

Hawai‘i

WGSC scientists, working through the 

Pacific Risk Management ‘Ohana (PRiMO)

initiative, in cooperation with researchers 

at The Pennsylvania State University and 

State of Hawai‘i representatives, assessed 

variations in community exposure to tsunamis across Hawai‘i (http://pubs.usgs.

gov/sir/2007/5208/). A similar analysis was 

done to examine current societal exposure 

to storm-surge inundation zones observed 

during Hurricane Iniki in 1992 (http://pubs.

usgs.gov/of/2008/1280/).

Florida

In collaboration with The Pennsylvania 

State University, WGSC examined societal 

vulnerability in Sarasota County, Florida, to 

hurricane storm-surge hazards that included 

sea-level rise scenarios. Research included 

an analysis of variations in community exposure to hazards and a workshop to document stakeholder perspectives on land-use 

strategies to adapt to hazards.

Exposure Assessments

sensitivity to 

tsunamis at 

the censusblock level. Risk is subjective and influenced by the 

perceptions and willingness to adapt of those 

at risk. The WGSC works with officials and 

the public to understand the societal context 

of risk and to effectively communicate results. 

This photograph shows a stakeholder pointing 

out vulnerability issues on a map of hurricane 

storm-surge zones enhanced by sea-level rise 

scenarios. (USGS photo by Nathan Wood.)

Stakeholder Engagement

Recent WGSC Contributions 

to Understanding Risk and 

Resilience to Natural Hazards

Washington

Working with the State of Washington 

Emergency Management Division, WGSC 

scientists have assessed variations in community exposure on the open-ocean coast to 

tsunami hazards related to a Cascadia subduction zone earthquake (http://pubs.usgs.gov/

sir/2008/5004/). Evacuation modeling is being 

done to examine the ability of at-risk individuals to reach higher ground before tsunami 

inundation. Variations in exposure to volcanic 

mudslide (lahar) hazards have been assessed 

for communities downstream of Mount 

Rainier (http://pubs.usgs.gov/sir/2009/5211/). 

WGSC scientists are working with the USGS 

Volcano Hazards Program and USGS Earthquake Hazards Program to examine community exposure to 4 other active volcanoes and 

20 earthquake scenarios.

Oregon

WGSC has assessed variations in community exposure along the Oregon coast to 

tsunami hazards associated with a Cascadia 

subduction zone earthquake (http://pubs.

usgs.gov/sir/2007/5283). Hotspots of demographic sensitivity to Cascadia tsunamis 

were mapped in collaboration with the University of South Carolina, and land-cover 

data derived from Landsat Thematic Mapper satellite imagery were shown to be an 

effective tool in assessing community ex-