Napa Valley's seismically reinforced winery buildings generally held up to the largest earthquake to hit Northern California in a quarter-century, but the precious wine piled inside often did not.
In winery after winery, oak wine barrels stacked high and weighing more than 250kg each came cascading down, renewing worries about a lightly regulated threat to safety in fault-riddled wine country.
Richard Ward, who worked in his south Napa Valley winery in the hours after the magnitude-6.0 quake to help workers restack barrels was one of many to say the time of the tremor - 3.20am - limited casualties.
Authorities say falling debris seriously injured three people, none apparently at wineries, which were then mostly unstaffed.
Had the quake happened one day later, Ward said, gesturing as workers used forklifts to right toppled empty barrels at his Saintsbury vineyard, "this place would have been full of people" working on this year's harvest.
Napa Valley's roughly 500 wineries are still compiling financial estimates for the quake's impact, according to spokeswoman Cate Conniff of the Napa Valley Vintners trade group. The most commonly reported damage was the fallen stacks of wine barrels.
The barrels each hold the equivalent of 25 cases of wine. At some wineries and wine-storage centres after the quake, spilled wine from broken barrels pooled over workers' feet and ran under doors to puddle on streets and footpaths.
Wine barrel storage sites, which can hold thousands of barrels belonging to many owners, said they too were still assessing the loss, but numerous full barrels had spilled to the ground in some.
In a few wineries with tasting rooms among the barrel stacks, tourists could have been in harm's way as well.
A 2004 report by the Oakland-based Earthquake Engineer Research Institute said wine barrel stacks posed "significant threats to life and property".
Materials in workplaces are supposed to be secured, but Peter Melton, a spokesman for the California state division of occupational safety and health, said there were no specific state laws or regulations covering wine barrel stacks.
Safety inspectors tended to see such stack collapses as inevitable in a large temblor, he said, and no wineries had been cited in the latest quake.
"I don't think they [barrel racks] were designed for an earthquake."
Beyond the economic losses of wine, "the risk to life safety is profound if it happens during the day", said Joshua Marrow, an earthquake safety specialist who has written on easing the dangers of the stacks for more than a decade.
Wineries typically use two-barrel racks to hold barrels, stacking them up to five or six high.
After a 2006 fire heavily damaged the Napa Valley Silver Oak family winery, chief executive David Duncan said he heeded seismic studies written by Marrow and rebuilt winery buildings to incorporate a seemingly simple change - switching to steadier four-barrel racks, even though that required buying bigger forklifts to move them.
At Silver Oak during the latest quake, the towers of wine barrels stood, although three barrels in partially full racks fell.
For Silver Oak, each full barrel that stayed put and did not break represented upward of US$32,500 ($38,850) in wine saved.
For colleagues who hesitate at the expense of retooling for different racks, "I tell them it's not as big an investment as having your barrels fall and crack open", Duncan said.
The danger of wobbly barrel stacks in earthquake areas had come up before, said Marrow, including after a 6.5-magnitude quake on California's Central Coast in 2003 and a 5.2-magnitude quake in Napa County in 2000.
Some Central Coast vintners began using shorter barrel stacks after the 2003 quake, said Chris Taranto, spokesman for a vintners' association there.
The recession dissuaded many vintners from spending to switch to steadier stacks, Marrow said.
Beyond recommending four-barrel racks, Marrow and other winery seismic safety experts have pointed to ways to better hold barrels in place, such as gates added to the front of them.
Wineries also can build sturdy steel cages in rooms where barrels are stacked, so workers have somewhere to run if a quake starts. Shorter stacks of barrels are safer than higher ones, according to Marrow.
The issue was not going to go away, he said, given that the majority of California's vineyards were in active seismic areas.
"Rolling vineyards generally were created by earthquake faults."