Bolstering Buildings Against the 'Big One'

By Sara Thompson

A massive earthquake is overdue to strike the coast of the Pacific Northwest. Few of the area’s cities and people are prepared for the devastation that will follow the temblor and subsequent tsunami.

That’s the conclusion of scientists working with the Federal Emergency Management Agency, according to an article published in the July 20, 2015, edition of the New Yorker magazine.

Geologists studying the Cascadia subduction zone say the “big one” has a 1 in 10 chance of striking in the next 50 years. The Cascadia fault begins in Northern California and continues for 700 miles through Oregon and Washington, ending in Canada near Vancouver Island. Portland, Seattle and around 7 million people live in the zone.

The Cascadia subduction zone has been active for thousands of years. It’s responsible for small rumblings and large volcanic eruptions. A subduction zone is the area where one tectonic plate is slowly moving beneath another. When the edges of the plates collide rather than subduct, violent earthquakes follow.

It’s only been in the last few decades that geologists identified the dangers of the Cascadia fault. Most buildings in the zone haven’t been designed with earthquakes in mind. As awareness grows of the eventuality of a big shake-up, some cities are retrofitting buildings and bridges to carry a greater seismic load.

What is seismic rehabilitation?

Older buildings, even those built as recently as the 1990s, often can’t withstand the impact of an earthquake. Some communities now require the seismic rehabilitation of structures.

Rehabilitation involves making the materials in walls better able to absorb the swaying caused by earthquakes. Concrete and masonry in older buildings are vulnerable to collapse when earthquakes strike. Retrofitting these materials with such things as steel bars and structural foam adhesive can prevent building failure and save lives.

Which buildings need seismic rehabilitation?

Any building not constructed to withstand seismic loads may require retrofitting. Public buildings such as schools and those that house emergency services are most in need of seismic rehabilitation. Buildings that are important historically are also often retrofitted. Seismic rehabilitation is less expensive than new construction, and in the case of historic buildings, it can preserve the original design and materials of the property.

Is funding available for seismic rehabilitation?

The Seismic Rehabilitation Grant Program of Oregon provides money for the retrofitting of certain public buildings. This program is for structures in public school districts, education service districts, community colleges and universities. Hospitals, fire and police stations, and other first responders’ organizations are also eligible for funding from this program.

FEMA manages programs that offer grants to reduce the hazards posed by natural disasters including earthquakes. The programs include assistance for states in areas with seismic risk. The agency also has agreements with nonprofit organizations, such as the Earthquake Engineering Research Institute, dedicated to earthquake safety. The EERI publishes several resources helpful for those responsible for seismic rehabilitation of buildings.

Image credit: Pixabay

Sara Thompson writes on behalf of Spray-On Foam + Coatings, Inc., a seismic rehabilitation contractor in Vancouver, Washington. Visit www.sprayonfoam.com or follow @sprayonfoam for more info.