1. U.S. Department of the Interior
U.S. Geological Survey
Population
vulnerability to
tsunami hazards
on the
U.S. West Coast
Nathan Wood, Jeanne Jones, Jamie Ratliff, Jeff Peters, Peter Ng
USGS Western Geographic Science Center
John Schelling Mathew Schmidtlein
Washington Military Dept. California State University, Sacramento
Rick Wilson Kevin Miller Bob Freitag
California Geological Survey CalOES Univ. of Washington

2. 2004 Indian Ocean earthquake and tsunami 2009 Samoa earthquake and tsunami
2010 Chilean earthquake and tsunami 2011 Tohoku earthquake and tsunami

3. Understanding population
vulnerability to tsunami hazards
Do we have people in
tsunami-hazard zones?
What demographic characteristics
influence resilience?
Will at-risk populations be
able to evacuate in time?
What can be done now to reduce
life loss and improve resilience?
Exposure
Sensitivity
Adaptive capacity
Risk reduction

4. Exposure
Do we have people in tsunami-hazard zones?

5. • Land-cover type
• Residents
• Employees
• Public venues
• Dependent-care facilities
• Community-support businesses
• Comparative indices
Available for
• Oregon (Cascadia threat)
• Washington (Cascadia threat)
• California (Multiple sources)
• Hawai’I (Multiple sources)
http://pubs.usgs.gov/sir/2012/5222/
Exposure
Do we have people in tsunami-
hazard zones?
Comparisons of community
exposure to tsunami hazards

6. Factors
• Residents
• Employees
• Community-support biz.
• Dependent-care facilities
• Public venues
• Beach and park visitors
Method
• Each divided by maximum
value in each category
• Normalized values added
up for range of 0 to 6
Exposure
Which communities
have the highest
number and
percentages of people in
tsunami-hazard zones?

7. Potential mobility and health issues Potential outreach and recovery issues
Sensitivity to tsunami hazards

8. Factors
• Race and ethnicity
• Age (< 5 yrs, > 65 yrs)
• Renters
• Single-mother households
• Institutionalized group quarters
• Non-institutionalized group
quarters
Method
• Each divided by maximum value
in each category
• Normalized values added up for
range of 0 to 6
Sensitivity
Which communities have the
highest percentages of
certain demographic
characteristics in tsunami-
hazard zones?

9. Adaptive Capacity
Can people reach high ground before waves arrive?
Pedestrian
evacuation
modeling

10. Adaptive Capacity
Can people reach high ground before waves arrive?

11. Increasing Adaptive Capacity
Can people reach high ground before waves arrive if they go faster?

12. Risk reduction
Where could vertical-evacuation strategies be
most effective in saving lives from tsunamis?
Project Safe Haven

13. Risk reduction
No one VE option can save everyone so tough choices need to be made

14. • % of residents within 25 minutes of high ground
• % of employees w/in 25 minutes of high ground
• % of dependent-care facilities w/in 25 min. of high ground
• % of community businesses w/in 25 min. of high ground
• % of public venues w/in 25 min. of high ground
Dotted lines
denote current
conditions with
no vertical
evacuation
Risk reduction
Comparing vertical-evacuation options

15. Risk reduction
Evacuation modeling to support post-disaster recovery
• Can provide insight on
impacts of recovery options
• May help identify additional
areas for recovery options
• Areas with life loss may
receive most attention but
other areas could have
been worse
• Post-disaster environment
may provide opportunity to
minimize risk in areas that
were just lucky during
current disaster
Evacuation modeling in Seward, Alaska
Today
Prior to 1964 earthquake

16. Primary points
• Community vulnerability to tsunami hazards varies
due to pre-existing differences in use of tsunami-
prone land and demographics of at-risk population
• Recovery efforts should reflect local needs, which
vary among communities and can be identified in
a holistic vulnerability assessment
• Adaptation may be education in one community
and vertical-evacuation construction in another
For more information
Nathan J. Wood, PhD
Research Geographer, U.S. Geological Survey
2130 SW 5th Avenue, Portland, OR 97201
Office - (503) 251-3291, Cell - (360) 991-6235
nwood@usgs.gov