Understanding Societal Vulnerability to Natural Hazards

With the recent disasters in the Indian Ocean and in the U.S. Gulf Coast, reducing potential losses from natural hazards in coastal communities is one of the critical issues of the 21st century. To reduce potential losses, public and private decision makers must understand the hazards in their communities and their vulnerability to these hazards. The USGS is helping local and state practitioners by augmenting its traditional expertise in natural hazards with improved capacity to assess vulnerability, defined here as the exposure, sensitivity, and resilience of a community (Figure 1).

Figure 1. Risk is a function of natural hazards and vulnerable human-environmental systems

Recent USGS research efforts have focused on assessing the vulnerability of coastal communities to catastrophic tsunamis and providing training opportunities to assess pre-event vulnerability and post-disaster recovery. This combination of efforts provides a holistic approach to risk analysis and shifts discussions of risk from simple inventories of exposed assets to community-wide understanding of system resilience. Specific project elements include

• Community Vulnerability to Tsunamis: Natural science models suggest that a Cascadia subduction zone earthquake could create tsunami waves that impact over 1,000-km of coastline in the U.S. and Canada (Figure 2). Coastal communities in Hawaii are threatened by distant earthquakes on the seismically-active Pacific Ocean margin, as well as local earthquakes. Although tsunami hazards are similar along these coasts, local variations in land-use, demography and economies create different levels of community vulnerability. Understanding these variations is critical if practitioners are to manage local risks. Using geographic information system (GIS) technology, USGS researchers are assessing variations in land-cover and land-use patterns, demographic characteristics, business and employment patterns, and critical-facility placement in Oregon, Washington, and Hawaii to determine where community vulnerability is greatest relative to predicted tsunami hazards. This information is helping local and State practitioners to develop realistic risk-reduction strategies and state and federal agencies to focus regional table-top response exercises.

  Figure 2. Recent research suggests that a Cascadia subduction zone earthquake could create tsunami waves that impact over 1,000-km of coastline in the U.S. and Canada. To understand local community vulnerability posed by these hazards, USGS researchers are assessing variations in land-cover and land-use patterns, demographic characteristics, and business and employment patterns

• Vulnerability Assessment Trainings: The USGS has created and delivered multi-hazard vulnerability assessment workshops in collaboration with the Oregon Partners for Disaster Resistance and Resilience, a statewide initiative that includes the Oregon Natural Hazards Workgroup, the USGS and Oregon Emergency Management, as well as local and state land use and emergency planners (Figure 3). This one-day training helps land use and emergency managers to understand the consequences and implications of their land use decisions and provides information that helps them meet requirements of the Disaster Mitigation Act of 2000. It also furthers USGS researchers in their efforts to develop indicators of societal vulnerability that include local values and priorities. Trainings have been held for counties in the Willamette Valley, along the Columbia Gorge, and in eastern Oregon.

  Figure 3. Representatives from Hood River County, Oregon, at the 2006 Vulnerability Assessment Workshop, in The Dalles, Oregon, January 25, 2006

• Post-Tsunami Disaster Recovery Forums: Working with the Oregon Natural Hazards Workgroup of the University of Oregon, USGS researchers held a post-disaster tsunami recovery forum with scientists and local practitioners in Cannon Beach, Oregon (Figure 4). This forum was conducted to assess the effectiveness of collaborative processes in integrating hazard and vulnerability information with local values for developing recovery strategies. This collaborative process serves as a bridge between science, practice and decision-making and presented a setting for building community resilience.

  Figure 4. USGS researcher Rachel Sleeter (left) speaking with representatives from U.S. Postal Service and Oregon Department of Transportation at the Post-Disaster Tsunami Recovery Forum in Cannon Beach, Oregon, March 2, 2006.

The vulnerability of communities to natural hazards is due to a complex interaction of natural processes, land-use decisions and resilience planning. Through efforts like those outlined above, the USGS is committed to improving the Nation's ability to understand how communities become vulnerable to natural hazards and what can be done to reduce risks

Publications and Websites:

Wood, N., and Soulard, C., in review, Variations in community exposure and sensitivity to tsunami hazards on the open-ocean and Straits of Juan de Fuca coasts of Washington: U.S. Geological Survey, Scientific Investigative Report, Reston, Virginia.

Wood, N., in review, Variations in community exposure and sensitivity to tsunami hazards on the Oregon coast: U.S. Geological Survey, Scientific Investigative Report, Reston, Virginia.

Wood, N., Church, A., Frazier, T., and Yarnal, B., in press, Variations in community exposure and sensitivity to tsunami hazards on the Hawaiian coast: U.S. Geological Survey, Scientific Investigative Report, Reston, Virginia.

Wood, N., in review, Use of midresolution land-cover data for comparing community vulnerability to tsunami hazards on the Oregon coast, external journal

Wood, N., LeDuc, A., and Mitchell, K., in preparation, The use of collaborative processes in post-disaster recovery planning for tsunami hazards, U.S. Geological Survey, Professional Paper, Reston, Virginia.

Wood, N., LeDuc, A., and Mitchell, K., 2007, Vulnerability Assessment Training, workshop held in Ontario, Oregon.

Wood, N., LeDuc, A., and Mitchell, K., 2006, Vulnerability Assessment Training, workshop held in The Dalles, Oregon.

Wood, N., LeDuc, A., and Mitchell, K., 2005, Vulnerability Assessment Training, workshop held in Portland, Oregon.

Wood, N., 2006, Variations in community vulnerability to tsunami hazards on the U.S. Pacific Northwest coast, Proceedings of the International Disaster Risk Conference, Davos, Switzerland

Wood, N., and Good, J., 2005, Perceptions of earthquake and tsunami issues in U.S. Pacific Northwest port and harbor communities, International Journal of Mass Emergencies and Disasters, 23 (3), 103-138.

Wood, N., and Good, J., 2004, Vulnerability of a port and harbor community to earthquake and tsunami hazards: the use of GIS in community hazard planning, Coastal Management, 32 (3), 243-269.

Wood, N., Good, J., and Goodwin, B., 2002, Community-based vulnerability assessment of a port and harbor to earthquake and tsunami hazards: Yaquina Bay, Oregon, Natural Hazards Review, 3 (4), 148-157.

Wood, N., Good, J., and Goodwin, B., 2002, Reducing vulnerability of ports and harbors to earthquakes and tsunamis, Solutions to Coastal Disasters '02 Conference Proceedings, American Society of Civil Engineers, Reston, Virginia, 949-963.

Wood, N., and Stein, D. 2001, A GIS-based vulnerability assessment of Pacific Northwest ports and harbors to tsunami hazards, Proceedings, International Tsunami Symposium '01, Seattle, Washington, 367 - 374