Great San Francisco Earthquake of 1906 (1 Viewer)

Ivan Drago

The California earthquake of April 18, 1906 ranks as one of the most significant earthquakes of all time. Today, its importance comes more from the wealth of scientific knowledge derived from it than from its sheer size. Rupturing the northernmost 296 miles (477 kilometers) of the San Andreas fault from northwest of San Juan Bautista to the triple junction at Cape Mendocino, the earthquake confounded contemporary geologists with its large, horizontal displacements and great rupture length. Indeed, the significance of the fault and recognition of its large cumulative offset would not be fully appreciated until the advent of plate tectonics more than half a century later. Analysis of the 1906 displacements and strain in the surrounding crust led Reid (1910) to formulate his elastic-rebound theory of the earthquake source, which remains today the principal model of the earthquake cycle.

At almost precisely 5:12 a.m., local time, a foreshock occurred with sufficient force to be felt widely throughout the San Francisco Bay area. The great earthquake broke loose some 20 to 25 seconds later, with an epicenter near San Francisco. Violent shocks punctuated the strong shaking which lasted some 45 to 60 seconds. The earthquake was felt from southern Oregon to south of Los Angeles and inland as far as central Nevada. The highest Modified Mercalli Intensities (MMI's) of VII to IX paralleled the length of the rupture, extending as far as 80 kilometers inland from the fault trace. One important characteristic of the shaking intensity noted in Lawson's (1908) report was the clear correlation of intensity with underlying geologic conditions. Areas situated in sediment-filled valleys sustained stronger shaking than nearby bedrock sites, and the strongest shaking occurred in areas where ground reclaimed from San Francisco Bay failed in the earthquake. Modern seismic-zonation practice accounts for the differences in seismic hazard posed by varying geologic conditions.

As a basic reference about the earthquake and the damage it caused, geologic observations of the fault rupture and shaking effects, and other consequences of the earthquake, the Lawson (1908) report remains the authoritative work, as well as arguably the most important study of a single earthquake. In the public's mind, this earthquake is perhaps remembered most for the fire it spawned in San Francisco, giving it the somewhat misleading appellation of the "San Francisco earthquake". Shaking damage, however, was equally severe in many other places along the fault rupture. The frequently quoted value of 700 deaths caused by the earthquake and fire is now believed to underestimate the total loss of life by a factor of 3 or 4. Most of the fatalities occurred in San Francisco, and 189 were reported elsewhere.

IMAGE #1> Collapsing of a string of houses.

IMAGE #2> The building ruins within the vicinity of Post and Grant Avenue after an earthquake struck the San Francisco area in 1906.

IMAGE #3> Crumbling buildings line a street and smoke rises in the background after the San Francisco earthquake.

IMAGE #4> 19th May 1906: The ruins of San Francisco after the terrible earthquake and fire. A view east down California Street, with St Mary's Church on the left and Grace Church on the right. The Ferry Building is visible in the top left.

IMAGE #5> Circa 1906: San Francisco on fire in the aftermath of the earthquake.

IMAGE #6> Union Street streetcar line, showing damage after the San Francisco, California earthquake, 1906.

IMAGE #7> The San Fransisco Earthquake of 1906. Telegraph Hill; From Ferry Building.

IMAGE #8> Photograph of St. Francis Hotel After the 1906 San Francisco Earthquake, 1906.

IMAGE #9> The quake was followed by a massive fire that swept through the business district.

IMAGE #10> Victorian homes on Howard Street near 17th Avenue that were damaged in the earthquake, San Francisco, California, 1906.

IMAGE #11 > 19th May 1906: Scenes of destruction following the San Francisco earthquake.

IMAGE #12> Photograph of the San Francisco Earthquake. Fires burning in wholesale and financial districts of San Francisco. Looking east from Nob Hill. Dated 1906.

IMAGE #13> Aerial view of the massive damage caused by an earthquake with an estimated magnitude of 7.9, San Franscico, California, May 28, 1906. The earthquake and subsequent fires caused thousands of deaths, left hundreds of thousands of people homeless, and cost hundreds of millions of dollars in 1906 currency. The photograph was taken about five weeks after the earthquake using an interconnected series of kites to elevated a stabilized camera about 2000 feet into the air.

IMAGE #14> The San Fransisco Earthquake of 1906. View from southeast slope of Nob Hill of fire burning, south of Market district.

IMAGE #15> 16th April 1906: The ruins of the City Hall in San Francisco after the earthquake.

IMAGE #16> Circa 1906: Aged Black man walks the charred remains of the San Francisco - Earthquake & Fire, 1906: Kearney St. from Telegraph Hill; only 3 to 5% of the damage was caused by the quake, the Balance by fire.

IMAGE #17> Scenes from the destruction and fire resulting from the San Francisco earthquake, CA, 1906. Among the neighborhoods depicted are the Business District, Chinatown, Nob Hill, and Union Square.

IMAGE #18> Colour photograph documents the aftermath destruction of the Great San Francisco Earthquake. Dated 1906.

IMAGE #19> San Franciscans crowd together while observing the fires raging in their city and moving towards their area, San Francisco, CA, 1906.





















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