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Earthquake Planner Warns Of "Soft-Story" Dangers

Written by on Wednesday, 05 November 2003 6:00 pm
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After Santa Cruz architect Michael O'Hern purchased two nearly identical Victorian homes on the same street he got around to retrofitting one with seismic upgrades but not the other before the Loma Prieta earthquake hit on Oct. 17, 1989. After the quake, damage to the upgraded home cost $5,000, but the other Victorian cost $260,000 to repair.

In a Northridge neighborhood in Southern California, one family spent $3,200 in 1993 to seismically upgrade the home built in 1911, but neighbors did nothing. When the 1994 Northridge quake hit, the home was the only one undamaged on both sides of a two-block stretch.

Retrofitting your home to better withstand the uplifting and lateral forces of an earthquake pays off, but it's not just the money.

If you have an older home, one with certain architectural features that make it more prone to damage, and live near active fault lines and don't perform seismic upgrades you are taking your life and the life of your family in your own hands.

As many as 160,000 homes -- single-family, condos and apartments in the San Francisco Bay Area alone -- will be uninhabitable after the next major earthquake in the Bay Area unless steps are taken to protect them, according to the Oakland, CA-based Association of Bay Area Governments (ABAG), a regional planning agency offering success and structural failure stories to heighten awareness that may have waned since the last big quake hit California.

Along with older homes and homes along fault lines, apartment buildings and other buildings with so-called "soft-story" structures are particularly vulnerable. Soft-story construction is over-hanging living space or other space supported by posts, a design often used to provide covered parking for residents in older multi-family housing. An estimated 15,000 at-risk soft-story buildings exist in the nine-county Bay Area and few landlords have taken the steps to strengthen their buildings.

Soft-story construction was responsible for 7,700 of the 16,000 housing units rendered uninhabitable by the Loma Prieta earthquake and more than 34,000 of the housing units rendered uninhabitable by the Northridge earthquake. During Northridge collapsing soft-story construction caused 16 deaths.

Multi-family housing is expected to account for 103,000 of the projected 160,000 homes likely to be rendered uninhabitable from an earthquake on a major Bay Area fault, according to an update this year of "Shaken Awake", an ABAG study of the Loma Prieta and Northridge Earthquakes.

ABAG says little has changed since 1999 when it surveyed landlords and found fewer than one percent of soft-story buildings had been retrofitted. Apartment officials surmise the reluctance to retrofit is due to the $3,000 to $9,000 cost per apartment to make soft-story construction safer, but costs could soar to much more -- including the loss of life -- if the work isn't completed.

"Many Bay Area residents still don't realize how vulnerable their own apartment or home is," said Jeanne Perkins, ABAG Earthquake Program Manager.

Along with the real-life stories exposing the hazards of not retrofitting and the life-saving benefits of doing the work, ABAG has revamped its Earthquake Maps and Information to help residents determine how well their home will stand up in an earthquake.

ABAG's "Residential Quake Safety Quiz" lets you determine the potential seismic threat to your home based on its proximity to a fault zone, existence of soft-story construction, age and height, building materials, and the building's footprint. The test can be used by residents who live in single-family homes, apartments, condos, townhomes and manufactured homes.

The score comes with advice for those who live in homes most susceptible to quake damages.

The Web site offers additional information on earthquake preparedness.

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  About the author, Broderick Perkins

Individual news stories are based upon the opinions of the writer and does not reflect the opinion of Realty Times.