Although the shaking was less intense, Trona's location on soft sediments that have eroded off a mountainside -- known as an alluvial fan -- caused the ground to act like quicksand, O'Dell said.
"That spreading of the soil undermined the foundations," he said, causing the base of buildings to come apart.
Chang said Trona's well-maintained homes seemed to withstand the shaking well, but some that had been abandoned and unoccupied suffered collapsed walls.
There are few public details so far about the structural damage suffered at the Naval Air Weapons Station, which has been directly on top of recent earthquakes. Conditions have forced personnel to evacuate.
Engineers and safety advocates say more can be done before the next big quake hits California. That includes bolting bookshelves to walls, arming kitchen cabinets and clothing dressers with toddler-safe locks, and using quake putty to affix breakable items to shelves.
Porter wants lawmakers to look to strengthen the state's minimum building requirements, which he says currently allows for construction just strong enough to not collapse in a quake.
"People think a new building is earthquake proof. But really, all it's supposed to do is not collapse and kill you," Porter said. "The damage can be so costly that you can't afford to fix it; that it doesn't make sense to fix it."
He urged lawmakers to reconsider a measure vetoed by then-Gov. Jerry Brown in 2018, which called for a tougher construction code to keep new buildings usable after a major earthquake.
Porter also said cities need to tackle the vulnerabilities presented by some of California's largest buildings.
Los Angeles, for instance, has yet to decide how it wants to address the risk of steel moment frame buildings constructed before the Northridge quake; the USGS has said it is plausible that five high-rise steel buildings in Southern California could topple in a magnitude 7.8 quake.
San Francisco has yet to decide on how it wants to deal with its stock of about 3,000 potentially vulnerable brittle concrete buildings, the kind that collapsed in the Northridge and Sylmar earthquakes.
"If we think it's expensive to fix those buildings, wait until we get the bill for not fixing them," Porter said. If a financial district is obliterated by the collapse of a single steel skyscraper, Porter said, "who is going to want to go into all the other ones that didn't collapse? Our trust in those buildings will evaporate."
It's time to move beyond simply preparing an earthquake kit as the main way to prepare for the Big One, O'Dell said.
"Being prepared is more than having your kit stocked, it's more than having a hard hat under your bed," O'Dell said. "We need to be preparing our buildings."
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