Northridge Meadows apartment complex
Northridge Meadows apartment complex

This is a plus from the recent string of earthquakes in the Los Angeles area. The LA City Council has instructed building officials to find apartment buildings vulnerable to collapse in a major quake.

L.A.’s survey would focus on the thousands of wood-frame buildings similar to the Northridge Meadows apartment complex, which collapsed and killed 16 people during the 1994 earthquake.

Until now, the city has rejected efforts to launch a citywide survey to figure out which structures might be vulnerable. Now they have not decided what to do once a building makes the list but making a list of buildings that could be vulnerable is a necessary first step.

Los Angeles Mayor Eric Garcetti said earlier this year that he supports some type of mandatory retrofitting of older buildings that have a risk of collapse in a major earthquake. He also said he wants buildings across Los Angeles to be graded for their seismic safety.

Apparently there is no city data exist to easily identify which structures are wood-framed and soft-story. Another class of buildings that pose particular risks in Los Angeles is older concrete buildings.

Soft-story wood-frame apartments are one of several types of buildings experts say are vulnerable to collapse in a big quake. Buildings are classified as having a “soft storey” if that level is less than 70% as stiff as the floor immediately above it, or less than 80% as stiff as the average stiffness of the three floors above it. A soft storey building is a multi-storey building in which one or more floors have windows, wide doors, large unobstructed commercial spaces, or other openings in places where a shear wall would normally be required for stability

http://www.latimes.com/local/la-me-earthquake-inspections-20140529-story.html