A handful of centenarians who survived the devastation joined hundreds of other people for a moment of silence and a memorial ceremony to remember one of the worst natural disasters in US history.
The annual wreath-laying at Lotta's Fountain, an inner city landmark where San Franciscans gathered after the quake to look for loved ones, was both a sombre remembrance and a celebration of the city's ability to rise from the ashes.
"The pioneering spirit that defines our past, I would argue defines our present, and gives me optimism of the future," said Mayor Gavin Newsom.
Most of the city's 400,000 residents were still in bed when the magnitude-7.8 earthquake struck at 5.12am on April 18, 1906.
The foreshock sent people scrambling, and the main shock arrived with such fury that it flattened crowded lodging houses.
The epicentre was a few miles offshore, but it was felt as far away as Oregon and Nevada. In 28 seconds, it brought down the City Hall.
Amid cracked chimneys, broken gas lines and toppled chemical tanks, fires broke out and swept across the city, burning for days.
Ruptured water pipes left fire fighters helpless, while families carrying what they could fled to parks that had become makeshift morgues.
Government officials said they hoped to use the centennial to remind all Californians to prepare for another deadly quake by making plans to live for three days without power, water and other essentials.