Why parts of LA will reflect present-day Turkey after a big quake
- US News
- February 15, 2023
- No Comment
Last week’s images from Turkey and Syria show us how devastating a large earthquake can be. When the 7.8 magnitude earthquake we expect on the San Andreas Fault happens, we will also see death and destruction, perhaps not as extensive as in Turkey, but far worse than most people expect. Instead of the post-earthquake usable buildings that many believe are guaranteed by the building code, the current regulation only requires that our buildings try not to collapse.
Office buildings, hospitals, homes and dwellings are only as good as the building codes in force at the time of their construction and the degree to which those codes have been enforced. Problems with enforcing the code on new construction and the lack of retrofitting of old, poor buildings will contribute to California’s death toll when the next major earthquake comes. Efforts are being made to fix these bugs and we hope more will be done in time.
But a third, potentially catastrophic flaw in our building code is not being addressed. When it comes to earthquake safety, the current international code is simply to prevent a building from killing someone while keeping construction costs as low as possible.
Basically, the code says this: you can choose to build a structure so weak that it’s a total financial loss after an earthquake, as long as it doesn’t kill anyone. Engineers need a more concrete definition of “don’t kill someone,” and that has become “avoid collapse.”
This rule, called the Life Safety Standard, aims to make the chance of a building collapsing in an earthquake very low, less than 10% for the worst tremors. That sounds good, but to put it another way, it means that no more than 10% of new buildings near a fault are likely to collapse in a major earthquake.
This is the code that has been used in Turkey for the last 20 years, although perhaps not fully enforced. It is also the code in California and most of the United States.
Let’s say the code works as designed in California and only a few new buildings collapse in a major earthquake—that doesn’t mean other new buildings won’t suffer enough damage to require demolition. When Christchurch, New Zealand experienced a 6.2 magnitude earthquake in 2011 – with shaking the maximum expected by building codes – only one modern building (the CTV building, built in 1986) collapsed, killing 115 people, but an additional 1,800 buildings were considered considered irreparable and were demolished. With a collapse rate of much less than 10%, the New Zealand civil engineers had done the job they were required to do to the code, but do we really think that is an acceptable result?
How many times do we have to see devastated cities and towns in other countries before we realize that this could be our future in California, Alaska, Washington, Oregon, Utah, Nevada, Missouri, or any of the other seismically active parts of the United States?
Our engineers and scientists have developed standards for a “functional recovery code” – that is, a building code aimed at giving us structures that can be repaired after a large earthquake that can be restored to function. Needless to say, functional recovery is a safer standard for human survival, as well as construction survival.
Most estimates of the increased cost of building to the Functional Restoration Standard add only about 1% to the building cost. An affordable condominium complex, Casa Adelante, was just being built in San Francisco, and its owners decided to design it to a functional-recreational standard. It was virtually cost neutral compared to the original rescue building design.
Two bills in the last five years proposing a statewide functional restoration standard for California made it through the legislature, only to eventually fail. We chose future economic disaster instead of paying a little more now.
Our elected officials can ensure we have buildings to use after the earthquake. We should stop building buildings that might not kill us but that we know will have to be demolished after a major earthquake. Sacramento should give us what most of us thought we already had.
Lucy Jones is the founder of the Dr. Lucy Jones Center for Science and Society and author of The Big Ones: How Natural Disasters Have Shaped Us (and What We Can Do About Them).