M5.4 LA Earthquake Reveals Importance of Seismic Rehabilitation

The Chino Hills Earthquake produced moderate ground motions that were widely felt throughoutSouthern California. This moderate earthquake caused damage to vulnerable structures and unbraced equipment and piping. Ceilings fell inLos Angeles International Airport and sprinkler breakage flooded a national brand department store inCanoga Park. Miyamoto International immediately mobilized a team of Structural Engineers to survey the damage following the earthquake.

A single-story unreinforced brick masonry building in downtownPomona suffered the most dramatic failure when a five-foot tall unbraced brick parapet collapsed into an alley behind the building. "Failures such as this are quite common in unreinforced masonry buildings, even in only moderate shaking," says Bryan Seamer of the Miyamoto International reconnaissance team.

Southern California is one of the most seismically active regions in the country, with large magnitude events of M7.5 and greater occurring every 150 years. The last great earthquake in the region was the 1857 M7.9 Fort Tejon earthquake on the Southern San Andreas Fault. That was 151 years ago. The more recent 1994 M6.7Northridge earthquake caused over $40 billion in economic loss. A Fort Tejon earthquake today would cause over $150b in losses (California Office of Emergency Services estimate). This would be comparable to the $147b in losses from the May 12, 2008 M8.0 Sichuan Earthquake inChina.

Californians are well aware of the earthquake risk and many have initiated strengthening programs. Miyamoto International has been actively engineering earthquake bracing projects in this area; many came through unscathed during theChino Hills event. Of these, a large lightly reinforced brick masonry, retail building inPomona that was recently retrofitted performed well. The Miyamoto reconnaissance team visited the building on the day of the earthquake and found no damage. The market was packed with shoppers. According to the market staff, the shaking was severe enough to knock cans and jars off shelves and into aisles, but the store continued operations immediately following the quake. The conclusion that can be drawn from this and many other observations is the value of cost-effective seismic retrofitting to protect occupants and minimize business interruption.

Miyamoto International provides engineering services to clients in all sectors, including education, commercial, high-rise, civic, transportation, industrial, high tech, healthcare and infrastructure. Our work includes new design, seismic and risk assessment, retrofit and rehabilitation, research and development and planning. With eight offices on the west coast;Tokyo, Japan; andIstanbul, Turkey; Miyamoto International is one of the largest and fastest growing structural engineering firms.

For more information contact Kit Miyamoto or Rebecca Cully with Miyamoto International, Inc. at 916-373-1995. Reference website: http://www.miyamotointernational.com .

Contact: Kit Miyamoto Rebecca Cully

               (916) 373-1995      (916) 373-1995

SOURCE Miyamoto International

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