Report documents populations, businesses in California tsunami-inundation zone

New research out of California that offers comprehensive documentation of the populations and businesses in the state’s maximum tsunami-inundation zone, information that may be of use in supporting tsunami preparedness and risk-reduction planning.

“To reduce potential impacts of future tsunamis, officials need to understand how communities are vulnerable to tsunamis and where targeted outreach, preparedness and mitigation efforts may be warranted,” notes the abstract for Community Exposure to Tsunami Hazards in California, a 60-page report prepared in co-operation with the California Emergency Management Agency and the California Geological Survey.

The report documents the variations among coastal communities in the amounts, types and percentages of developed land, human populations and businesses in the maximum tsunami-inundation zone. It includes land in 94 incorporated cities, 83 unincorporated communities and 20 counties on the California coast.

U.S. Census Bureau data from 2010 indicates the tsunami-inundation zone contains 267,347 residents. In addition, based on 2011 economic data from Infogroup, the zone contains significant non-residential populations, including 168,565 employees at 15,335 businesses that generate approximately $30 billion in annual sales.

More specifically, the tsunami-inundation zone also contains the following:

• numerous dependent-population facilities, such as schools and child daycare centres, which may have individuals with limited mobility;
• a substantial number of facilities that provide community services – including banks, religious organizations and grocery stores – where local residents may be unaware of evacuation procedures if previous awareness efforts focused on home preparedness;  and
• numerous recreational areas – such as amusement parks, marinas, city and county beaches, and state and national parks – which attract visitors who may not be aware of tsunami hazards or evacuation procedures.

During peak summer months, the abstract notes, “estimated daily attendance at city and county beaches can be approximately six times larger than the total number of residents in the tsunami-inundation zone.”

The cities of Alameda, Belvedere, Crescent City, Emeryville, Oakland and Long Beach have the highest combinations of the number and percentage of people and businesses in tsunami-prone areas. “Community exposure to tsunamis in California varies considerably — some communities may experience great losses that reflect only a small part of their community and others may experience relatively small losses that devastate them,” the abstract adds.