Risks and needs brought to forefront with latest earthquakes
When the magnitude 7.1 earthquake struck Southern California near Ridgecrest on July 5, it was the largest in two decades. Of course, that statistic is followed by the 6.4 foreshock that struck the same area a day earlier. This pair of SoCal earthquakes was enough to shake up those who may have forgotten how impactful such temblors can be to buildings and how important earthquake-resistant structures are in this region.
Surprisingly good news
After the earthquake, structural engineers headed straight to the small town in the Mojave Desert to study what they expected to be destruction. Instead, they were a bit astonished with what they found. “Ridgecrest, I’m just amazed,” California Earthquake Authority structural engineer Janiele Maffei told The Los Angeles Times.
The damage wasn’t as great because many of the homes lacked vulnerable materials such as unreinforced masonry and brittle concrete. In fact, Ridgecrest suffered far less than Napa and Paso Robles, locations where downtown buildings crumbled during less powerful earthquakes. Those towns had older structures than the 1980s construction in Ridgecrest.
Being shake ready
While Ridgecrest faired relatively well, eyes are now on other buildings throughout SoCal. Along with the aftershocks, experts warn that “the big one” is still very possible. Structures tend to handle vertical movement relatively well because that’s often where engineers put their focus, but earthquakes can bring additional directional forces that can cause shifting and destabilization.
Buildings that are most vulnerable are older, low-slung and “soft story” apartments. These are quite common throughout Southern California, including tens of thousands in Los Angeles County.
“I don’t want to frighten people,” Kenneth O’Dell, president of the Structural Engineers Association of Southern California, told NBC News after the earthquakes in July. “But I think it’s important to be transparent. This is a real issue.”He notes that a powerful temblor could either collapse these old buildings or shift them so dramatically that they’re uninhabitable.
While there are seismic construction codes in place, buildings could still become so severely damaged during a major quake that they cannot be used for months or even years afterwards. Thus, lawmakers like Assemblyman Adrin Nazarian (D-North Hollywood)have proposed bills that would toughen rules on how strong new buildings should be and require cities to identify existing buildings at risk of collapse. Seismologist Lucy Jones is also a big advocate of increasing California’s minimum building standards.
But retrofitting costs money. Thus, a dilemma arises when having to weigh safety with such large expenses. Some hospitals are having to come up with concepts about how to deal with such a tough decision. Should taxpayers foot the bill or should they adopt a cap-and-trade-like system where hospitals could buy permits allowing them to have noncompliant beds?
H. Kit Miyamoto, a member of the California Seismic Safety Commission, a government body that advises the State Legislature and the governor on earthquake issues, notes, “Throwaway buildings equal a throwaway city.”
The challenge before them now has some engineers looking across the ocean to Japan, where that country is ten times more prone to earthquakes and constructs buildings to survive such shaking. “Do we want to be more like Japan and are we willing to pay the price?” Joyce Fuss, president of the Structural Engineers Association of California, told The New York Times.“A lot of people would say ‘no’ and maybe some people would say ‘yes.’”