U.S. Department of the InteriorU.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 SchmidtleinWashington Military Dept. California State University, Sacramento

Rick Wilson Kevin Miller Bob FreitagCalifornia Geological Survey CalOES Univ. of Washington

2004 Indian Ocean earthquake and tsunami 2009 Samoa earthquake and tsunami

2010 Chilean earthquake and tsunami 2011 Tohoku earthquake and tsunami

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

ExposureDo we have people in tsunami-hazard zones?

• 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/

ExposureDo we have people in tsunami-hazard zones?

Comparisons of community exposure to tsunami hazards

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

ExposureWhich communities have the highest number and percentages of people in tsunami-hazard zones?

Potential mobility and health issues Potential outreach and recovery issues

Sensitivity to tsunami hazards

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?

Adaptive CapacityCan people reach high ground before waves arrive?

Pedestrian evacuation modeling

Adaptive CapacityCan people reach high ground before waves arrive?

Increasing Adaptive CapacityCan people reach high ground before waves arrive if they go faster?

Risk reductionWhere could vertical-evacuation strategies be most effective in saving lives from tsunamis?

Project Safe Haven

Risk reductionNo one VE option can save everyone so tough choices need to be made

• % 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 reductionComparing vertical-evacuation options

Risk reductionEvacuation 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

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 informationNathan J. Wood, PhDResearch Geographer, U.S. Geological Survey2130 SW 5th Avenue, Portland, OR 97201Office - (503) 251-3291, Cell - (360) 991-6235nwood@usgs.gov