The images from Turkey and Syria over the past week show how devastating a major earthquake can be. When the magnitude 7.8 earthquake we expect hits the San Andreas fault line, we will also see death and destruction, perhaps not as extensive as in Turkey, but much worse than most people expect. Instead of the usable post-earthquake buildings that many people think are guaranteed by the building code, the current code only asks that our buildings try not to collapse.
Office buildings, hospitals, apartments and homes are only as good as the building codes in effect at the time they were built and the extent to which those regulations were adhered to. Code enforcement issues in new construction and the lack of retrofitting of old, bad buildings will add to California’s death toll when the next major earthquake comes. Efforts to overcome these failures are underway and we can hope that 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 solely about preventing a building from killing someone while keeping construction costs as low as possible.
The code essentially says this: You can choose to build a structure so weak that it will be a total financial loss after an earthquake, as long as no one is killed. Engineers need a more concrete definition for “don’t kill someone”, and that has become “avoid collapse”.
This rule, called the life safety standard, is really just designed to make the probability of a building collapsing in an earthquake very low, less than 10% in the worst tremors expected. That sounds good, but put another way, it means that no more than 10% of new buildings near a fault are expected to collapse when a major earthquake hits.
This is the code that has been used in Turkey for the past 20 years, if not fully enforced. It is also code in California and most of the United States.
Let’s say the code works as planned in California and only a few new buildings collapse in a major earthquake – that doesn’t mean other new buildings won’t be so badly damaged that they need to be torn down. When Christchurch, New Zealand, experienced a magnitude 6.2 earthquake in 2011 – with shaking that was the maximum expected by building codes – only one modern building (the CTV Building, built in 1986) collapsed, which killed 115 people, but an additional 1,800 buildings were deemed beyond repair and were demolished. With a collapse rate well below 10%, New Zealand’s structural engineers had done the job the code required of them, but do we really think this is an acceptable result?
How many times do we have to see destroyed 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 that aims to give us structures that can be repaired after major damage, and whose function can be restored. Needless to say, functional recovery is a safer standard for human survival and building survival.
Most estimates of the higher cost to build to functional recovery standard only add about 1% to the cost of construction. An affordable residential complex, house ahead, was just built in San Francisco and the owners chose to design to a functional recovery standard. It was virtually cost neutral compared to the original design for a life-safe building.
Two bills in the past five years proposing a statewide functional recovery standard for California have made it through the legislature only to ultimately fail. We have chosen a future economic catastrophe instead of paying a little more now.
Our elected officials can make sure we have buildings that we can use after the earthquake. We need to stop building buildings that may not kill us, but that we know will have to be torn down 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 the author of “The Big Ones: How Natural Disasters Have Shaped Us (and What We Can Do About Them).”