The Great San Francisco Earthquake was the stuff of legend—but it really happened. A vibrant city saddled with a corrupt government was laid low by a colossal earthquake and subsequent fire. Rising from the ruins a brand-new gleaming metropolis quickly regained its feet as the people, united, led by public-minded men of wealth, set San Francisco on a path to glory. And the legacy of that fateful time extends to this day.
The Mainshock and Fires
The mainshock began on the San Andreas fault off the coast near San Francisco at 5:12 in the morning of 18 April 1906. Many years later, researchers assigned it a magnitude of 7.8 or so. Violent shaking went on for some 60 seconds. The rupture extended far to the north and south, 430 kilometers in all. Parts of the fault were offset by as much as 6 meters. By day's end and dozens of aftershocks later, much of San Francisco was a shambles and large fires had broken out, threatening the rest.
The fires burned for three more days as water supplies, damaged by ground movement, were reduced to a trickle. Even now, true San Franciscans call the debacle of 1906 the Great Earthquake and Fire, but in fact fires are part and parcel of any large earthquake. Separating the calamity into two lesser calamities is one way for people to take it in stride. In this case, both the public and the authorities did their best to downplay, deny and refuse to learn from the earthquake while taking pride in their ability to bounce back afterward.
Part of every earthquake's aftermath is a frantic haste to return to normal. The newspapers and civic leaders insisted that the earthquake had made central California safer. Nevertheless, building codes were eventually strengthened in the face of public demand. Dangerous filled land was swiftly reoccupied once the wreckage was cleared. In fact, more fill was created when the rubble was dumped in a topographic basin on the north side of town. The great Panama-Pacific Exhibition of 1915, which signaled Frisco's recovery to the world, was constructed on that fill. (Years later, housing built on the site collapsed in the 1989 earthquake.)
The great burst of rebuilding gave San Francisco its current character, as much of the housing is of the same vintage and style. The city regained its vigor and kept its position as principal city of the West. The populace returned, many after living for years in large refugee camps. A handful of the tiny refugee cabins survive and are being preserved today.
A Civic Legacy
San Francisco's remarkable civic spirit was reborn with its buildings. Shortly after the quake, the corrupt administration of Mayor Eugene Schmitz was dismantled, and a new San Francisco was built from the ground up. This infrastructure, financed with public bonds, paid off in long-lived prosperity. And the colorful story of the Great Earthquake became an element of the city's image and culture.
Every year in the early morning of April 18, earthquake survivors and their friends have gathered at Lotta's Fountain to observe the anniversary. After a century, the survivors have dwindled to a handful who were infants at the time. But the 1906 Earthquake Centennial Alliance, composed of many agencies, museums, corporations and educators, is at work on keeping awareness alive in this proud city. One great success was the centennial scientific conference held in 2006.
The Birth of Modern Seismology
The Bay area's geologists leaped into action after the earthquake. A commission was quickly named under the leadership of Andrew Lawson, of the University of California at Berkeley, and within two years it had compiled maps, photographs and personal accounts from the whole earthquake region. The "Lawson Report," published by the Carnegie Institute when state funding was not offered, set the gold standard for this kind of investigation and has remained in print since its reissuance in 1969.
Harry F. Reid, an academic geologist from Johns Hopkins University who was part of the commission, originated the "elastic rebound" theory of earthquakes on the basis of the 1906 data. This explanation of the earthquake cycle in terms of the strain energy contained in large bodies of rock remains a cornerstone of our understanding of earthquakes.
PS: Some landmarks from the 1906 earthquake remain standing in San Francisco today; see a gallery of photos and seek out the sites next time you visit.