Soft-Story Buildings in San Francsico and Their Significance
Why are Soft-Story Buildings Important to San Francisco
Soft-story buildings do not perform well in earthquakes. Without a seismic retrofit, many of San Francisco's soft-story wood-frame buildings are expected to collapse or to suffer damage beyond repair in the large earthquake scientists say will hit San Francisco within decades.
Large Earthquake Predicted in the San Francisco Bay Area
Seismologists predict a 63% probability that the San Francisco Bay Area will experience a magnitude 6.7 earthquake in the next 30 years.
USGS: San Francisco Bay Area Earthquake Probabilities
UCERF: Map of Earthquake Probabilities, Major California Faults
Earthquake Danger to Soft-story Buildings in San Francisco
A study was performed on 4,300 wood-frame buildings built before January 1, 1978 in San Francisco with five or more residential units on three or more stories. All of these buildings may have a soft story condition, but the study determined that about 2800-2900 of these buildings likely have this condition. This was determined through a sidewalk visual survey. The study analyzed these buildings, coming to the following determinations:
Extent: 80 percent of those soft-story buildings would collapse or be destroyed beyond repair.
Residents: 58,000 San Francisco residents live in soft-story buildings.
Businesses: 2,000 San Francisco businesses are situated in soft-story buildings.
Workers: 6,900 people work in soft-story buildings.
Damage: A major quake would cause $4 billion in damage to San Francisco soft-story buildings.