Twenty years ago, downtown Napa was a place where tourists stopped only when they needed car repairs.

But in less than two decades, this riverfront city has become a dining and entertainment destination at the heart of California’s wine country. Comedian Dana Carvey is performing here next month, and Iron Chef Masaharu Morimoto has a restaurant downtown.

The 6.0-magnitude earthquake Sunday toppled building facades, shattered windows and left many blocks downtown cordoned off. But after decades of flood mitigation, earthquake proofing and downtown redevelopment, the tremor was a reminder to vintners and merchants of the fragility of the success of their small city on the Napa River.

“For someone like me, the idea that Napa has destination restaurants that are nationally known, that’s incredible,” said winemaker David Graves, co-founder of Saintsbury Winery, a small outfit in Napa that suffered little damage in the earthquake.

The city of Napa, overlooked for decades as tourists passed it straight to Napa County’s vineyards, “symbolizes both the past and the future” of wine country, said Graves.

“Our wine business dates back to the 1850s, and [the city of] Napa has always been very important as part of that,” he said, referring to the Napa wines that used to be shipped along the river to San Francisco. Though only 4 percent of California’s wine-grape harvest comes from Napa, the wine industry generates about $13 billion in revenue for Napa County, attracting about 3 million tourists annually.

“In some ways, Napa’s renaissance in the last 25 years is resuming its rightful place as an important part of the wine business,” Graves said.

But this past weekend, state inspectors “red-tagged” 90 to 100 Northern California homes, declaring them unsafe for entrance. In the city of Napa, 49 buildings were red-tagged as of Monday morning. Four mobile homes in the town burned down, and 70,000 residents were initially without power, though by Monday morning, almost everyone in the city had power. The earthquake was centered just seven miles south of the Napa County Airport, near the heart of wine country, at the start of the grape harvest.

Vinters said it was good that the quake happened during the harvest — before their wine tanks and aging barrels were full with the 2014 vintage.

“Its early enough in the harvest right now — the little bit of wine that we have at the winery right now, it’s just going into barrels,” said Donald Patz, an owner of the Patz & Hall winery in Sonoma. Patz said that if the earthquake had not happened during harvest season and if it had been a little farther south, “we could have lost our entire 2013 vintage.”

At Bouchaine Vineyards, a small Napa winery, spokeswoman Carla Bosco said, “We just brought in our first loads of grapes on Thursday last week.” She said 40 barrels were damaged in the earthquake. “Our associate winemakers said it looked like a Jenga block tower that had fallen open, and there was wine several inches deep,” Bosco said.

But the 40 damaged barrels were from a total of about 1,000. So losses, Bosco said, were minimal.

Structural engineers Steve Heyne, left, and Chris Jonas, right, walk past the earthquake-damaged Goodman Library in Napa, Calif. (Eric Risberg/ASSOCIATED PRESS)

The early assessment in Napa on Monday was that there were no major losses of wine, though many historic winery buildings were damaged. “Many of the wineries in the lower Napa area sustained damages similar to ours . . . there were a few wineries who had older buildings and especially older chimneys that sustained damages,” said Bosco.

In downtown Napa, Joe Peatman, the owner of Downtown Joe’s, a restaurant near the river that serves fish and chips, seafood, steaks and burgers, said he retrofitted his 120-year-old brick building in 2010 for a seismic event. On Monday, he was thankful.“It had withstood all previous floods and earthquakes,” Peatman said

But next door to Peatman’s restaurant, at the historic Alexandria Square building, a redeveloped office and restaurant complex, the brick facade on the northwest side collapsed, leaving the restaurants closed.

Mike DeSimoni Jr., a local developer who spearheaded much of downtown Napa’s rebuilding since the 1990s and whose family owns the Alexandria Square, said that in the Morimoto restaurant, wine bottles had fallen to the floor, but next to the bottles “were stacked-three-high martini glasses that didn’t even fall.” He said that his buildings on the east side of the river were fine and that the earthquake’s damage seemed erratic.

The earthquake, which struck about 3:20 a.m., was the biggest one in Northern California since the 1989 Loma Prieta earthquake that shook San Francisco, Oakland and Monterey. That earthquake killed 62 people, collapsed a segment of the Bay Bridge connecting Oakland to San Francisco and destroyed a two-level segment of a raised freeway in Oakland, killing 42 people below it.

On Sunday evening, U.S. Geological Survey scientists were estimating the likelihood of a 5.0-magnitude or greater aftershock to be 36 percent.

An early-warning system at the University of California at Berkeley gave a 10-second notice of the earthquake. Though the message reached few people, it was a reason for California to continue pursuing a statewide earthquake warning system, said Mark Ghilarducci, director of the California Governor’s Office of Emergency Services, at a news media conference near Sacramento on Sunday. It would, he said, possibly give people 90 seconds of warning — enough to take cover. The Berkeley warning, Ghilarducci said, “does show that that system has validity.”

Harless is a freelance writer.