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1906 San Francisco earthquake

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Arnold Genthe's famous photograph of San Francisco following the earthquake, looking towards the fire on Sacramento Street.

The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco and the coast of northern California at 5:12am on Wednesday, April 18, 1906. The most widely accepted magnitude for the earthquake is a moment magnitude (Mw) 7.8; however, other values have been proposed from 7.7 to as high as 8.3 [1]. The mainshock epicenter occurred offshore about 2 miles from the city. It ruptured along the San Andreas Fault both northward and southward for a total length of 296 miles (477 km) [2]. Shaking was felt from Oregon to Los Angeles, and inland as far as central Nevada. The earthquake and resulting fire would be remembered as one of the worst natural disasters in the history of the United States, comparable in devastation to the Galveston Hurricane of 1900 and Hurricane Katrina in 2005.

At the time, only 478 deaths were reported; the figure was concocted by government officials who felt that reporting the true death toll would hurt real estate prices and efforts to rebuild the city. Also, hundreds of casualties in Chinatown went ignored and unrecorded due to racism at the time. Today, this figure has been revised to a conservative estimate of at least 3,000 -- some estimates have put it as high as 6,000 deaths. Most of the deaths occurred in San Francisco itself, but 189 were reported elsewhere across the San Francisco Bay Area. Other places in the Bay Area such as Santa Rosa, San Jose, and Stanford University also suffered severe damage.

Houses damaged by the earthquake.

Between 225,000 and 300,000 people were left homeless out of a population of about 410,000. Half of the refugees fled across the bay to Oakland. Newspapers at the time described Golden Gate Park, the Presidio, the Panhandle, and the beaches between Ingleside and North Beach being covered with makeshift tents.

The earthquake and fire would leave a long-standing and significant impression on the development of California. At the time of the disaster, San Francisco had been the ninth-largest city in the United States and the largest on the West Coast, with a population of about 410,000. Over a period of 60 years, the city had become the financial, trade and cultural center of the West; operated the busiest port on the West Coast; and was the "gateway to the Pacific", through which growing US economic and military power was projected into the Pacific and Asia. Over 80% of the city was destroyed by the earthquake and fire. Though San Francisco would rebuild quickly, the disaster would divert trade, industry and population growth south to Los Angeles, which during the 20th century would become the largest and most important urban area in the West. However, the 1908 Lawson Report, a study of the 1906 quake, showed that the very same San Andreas Fault which had caused the disaster in San Francisco ran close to Los Angeles as well.

The earthquake was the first natural disaster of its magnitude to be documented by photography and motion picture footage. Furthermore, it occurred at a time when the science of seismology was blossoming. The overall cost of the damage from the earthquake was estimated at the time to be around $400 million.

The Army's Rescue

"Thank God for the Soldiers". San Francisco Earthquake, 1906. Source: USA Center of Military History
  • The city fire chief sent an urgent request to the Presidio, an Army post on the edge of the stricken city, for dynamite. BG Frederick Funston, commanding the Department of California and a resident of San Francisco had already decided the situation required the use of troops. Collaring a policeman he sent word to the Mayor of his decision to assist. Martial law was never declared, however, and troops took guidance from civilian authorities.
  • During the first few days soldiers provided valuable services patrolling streets to discourage looting and guarding buildings such as the U.S. Mint, post office, and county jail. They aided the fire department in dynamiting to demolish buildings in the path of the fires. The Army also became responsible for feeding, sheltering, and clothing the tens of thousands of displaced residents of the city. This support prompted many citizens to exclaim, "Thank God for the soldiers!" Under the command of MG Adolphus Greely, Commanding Officer, Pacific Division, Funston's superior, over 4,000 troops saw service during the emergency. On July 1, 1906 civil authorities assumed responsibility for relief efforts and the Army withdrew from the city.
  • As fires rage through San Francisco soldiers, dressed in olive drab service dress with strapped leggings and wearing campaign hats with light blue cords designating infantry, unload one of many civilian wagons pressed into service with their drivers. (In addition to supplies from Army depots, food, including much flour, came from cities all over the United States.) The officer with the black visored service cap is a lieutenant colonel of infantry. With his olive drab, single breasted sack coat, with four chokedbellow pockets, low falling collar and dull finish bronze metal buttons he wears olive drab service breeches and russet leather boots. The officer and the artillery sergeant known by his scarlet hat cord carry .38 caliber service revolvers; the rifles shown are the new .30 caliber 1901 "Springfields."

Geology

The 1906 San Francisco earthquake was caused by a slip on the San Andreas Fault. This fault runs the length of California from the Salton Sea in the south to Cape Mendocino to the north, a distance of about 800 miles (1287 km). The earthquake ruptured the northern third of the fault for a distance of 296 miles (477 km). The maximum observed surface displacement was about 20 feet (6 m); however, geodetic measurements indicate displacements of up to 28 feet (8.5 m) [3].

A strong foreshock preceded the mainshock by about 20 to 25 seconds. The strong shaking lasted about 60 seconds. The shaking intensity as described on the Modified Mercalli Intensity Scale reached VIII in San Francisco and up to IX in areas up the coast like Santa Rosa where destruction was almost complete.

Subsequent fires

Fires after the quake.
Smoldering ruins of San Francisco, taken from the tower of the Ferry Building on Market Street.

As damaging as the earthquake and its aftershocks were, the fires that burned out of control afterward were much more destructive. Overall, it is estimated that fire damage accounted for 90% of the total destruction resulting from the earthquake. Fires broke out in many parts of town, some initially fueled by natural gas mains broken by the quake. Other fires were the result of arson, and campfires set by refugees. The fires lasted for four days and nights. Some property owners set fire to their damaged buildings, because most insurance policies covered fire losses while prohibiting payment if the building had only sustained earthquake damage. Captain Leonard D. Wildman of the U.S. Army Signal Corps reported that he "was stopped by a fireman who told me that people in that neighborhood were firing their houses... They were told that they would not get their insurance on buildings damaged by the earthquake unless they were damaged by fire."

Some of the greatest loss from the fires was in scientific laboratories that existed in the city. Alice Eastwood, the Curator of Botany at the California Academy of Sciences in San Francisco had made several excursions to Monterey County to collect specimens of rare plants, including one where she discovered "P. hickmansii", Hickman's potentilla. After the earthquake, she immediately rushed to the heavily damaged California Academy of Sciences building on Market Street, and climbed metal railings of collapsed staircases to reach the herbarium on the sixth floor. She succeeded in saving nearly 1500 specimens, including the entire type specimen collection, before the remainder of the largest botanical collection in the western United States was consumed in the resulting fire.[1][2] The entire biochemical laboratory and all the records of Benjamin R. Jacobs, a biologist who was researching the nutrition of everyday foods, was lost, including much of his research into the enrichment of grains, putting his invention of the process back several years.

As water mains were also broken, the city fire department had few resources with which to fight the fires. Several fires in the downtown area merged to become one giant inferno. One journalist at the time wrote that readers elsewhere should understand that it was not a fire in San Francisco, but rather a fire of San Francisco. The fire ultimately destroyed over 500 city blocks of the downtown core from Van Ness Avenue, an arterial thoroughfare that bisects the center of the city, to the docks on San Francisco Bay.

It was erroneously reported that mayor Eugene Schmitz and General Frederick Funston declared martial law. Schmitz did, however, issue an edict allowing police, vigilante patrols, and military troops to shoot looters on sight, and some 500 people were shot and killed. Funston tried to bring the fire under control by detonating blocks of buildings around the fire to create firebreaks with all sorts of means ranging from black powder and dynamite to even artillery barrages. Often the explosions set the ruins on fire or helped spread it. Despite its shortcomings, it did eventually prove effective in stopping the fire from spreading westward to the remaining half of the city.

Relocation and housing of displaced

One of the eleven camps in 1906

The Army built 5,610 redwood and fir "relief houses" to accommodate 20,000 displaced people. The houses were designed by John McLaren, and were grouped in eleven camps, packed close to each other and rented to people for two dollars per month until rebuilding was completed. They were painted olive drab, partly to blend in with the site, and partly because the military had large quantities of olive drab paint on hand. The camps had a peak population of 16,448 people, but by 1907 most people had moved out. The camps were then re-used as garages, storage spaces or shops.

Aftermath & reconstruction

Almost immediately after the quake (and even during the disaster), planning and reconstruction plans were hatched to quickly rebuild the city. One of the more famous and ambitious plans came from famed urban planner Daniel Burnham. His bold plan called for, among other proposals, Haussmann-style avenues, boulevards, arterial thoroughfares that radiated across the city, a massive civic center complex with classical structures, and what would have been the largest urban park in the world, stretching from Twin Peaks to Lake Merced with a large atheneum at its peak. But this plan was dismissed at the time as impractical and unrealistic. For example, real estate investors and other land owners were against the idea due to the large amount of land the city would have to purchase to realize such proposals.

While the original street grid was restored, many of Burnham's proposals inadvertently saw the light of day, such as a neoclassical civic center complex, wider streets, a preference of arterial thoroughfares, a subway under Market Street, a more people-friendly Fisherman's Wharf, and a monument to the city on Telegraph Hill, Coit Tower.

File:Row of refugee shacks.jpg
A row of refugee shacks in 1907

Furthermore, plans to move Chinatown and the poor away from the city center failed, as Chinatown was rebuilt in the newer, modern, Western form that exists today. In fact, the destruction of City Hall and the Hall of Records enabled thousands of Chinese immigrants to claim residency and citizenship, and bring in their relatives from China.

Reconstruction was swift, and largely completed by 1915, in time for the Panama-Pacific Exposition which celebrated the reconstruction of the city and its "rise from the ashes".

Since 1915, the city has officially commemorated the disaster each year by gathering the remaining survivors at Lotta's Fountain, a fountain in the city's financial district that served as a meeting point during the disaster for people to look for loved ones and exchange information.

Panorama of San Francisco in ruins from Lawrence Captive Airship, 2000 feet above San Francisco Bay overlooking water front. Sunset over Golden Gate. May 1906.

Centennial commemorations

The 1906 Centennial Alliance has been set up as a clearing-house for various centennial events commemorating the earthquake. Award presentations, religious services, a National Geographic TV movie, a projection of fire onto the Coit Tower , memorials, and lectures are to be held or have already been held. The USGS Earthquake Hazards Program has issued a series of Internet documents, and the tourism industry is promoting the 100th anniversary as well.

Analysis

The San Andreas Fault runs in a northwest-southeast line along the coast. The numbers on the fault line indicate how far the ground surface slipped (in feet) at that location as a result of the 1906 earthquake.
  • For a number of years, the epicenter of the quake was assumed to be near the town of Olema, in the Point Reyes area of Marin County, because of evidence of the degree of local earth displacement. In the 1960s, a seismologist at UC Berkeley proposed that the epicenter was more likely offshore of San Francisco, to the northwest of the Golden Gate. However, the most recent analysis by the United States Geological Survey (USGS) shows that the most likely epicenter was very near Mussel Rock on the coast of Daly City, an adjacent suburb just south of San Francisco [4].
  • The most 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 (earthquake liquefaction). Modern seismic-zonation practice accounts for the differences in seismic hazard posed by varying geologic conditions.
  • An analysis of the 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.
  • The USGS estimates that the earthquake measured a powerful 7.9 on the moment magnitude scale. The earthquake caused ruptures visible on the surface for a length of 470 kilometers (290 miles). Modified Mercalli Intensities of VII to IX paralleled the length of the rupture, extending as far as 80 kilometers inland from the fault trace.

References

  • Lawson, Andrew C., The California Earthquake of April 18, 1906. Report of the State Earthquake Investigation Commission, Carnegie Institution of Washington, 1908.
  • Reid, H. F., The Mechanics of the Earthquake, Vol. 2 in The California Earthquake of April 18, 1906. Report of the State Investigation Commission, Carnegie Institution of Washington, 1910.
  • Eastwood, Alice, The Coniferae of the Santa Lucia Mountains
  • Double Cone Quarterly, Fall Equinox, volume VII, Number 3 (2004)


See also

Wikimedia Commons has media related to San Francisco earthquake of 1906.
  1. ^ Alice Eastwood, The Coniferae of the Santa Lucia Mountains
  2. ^ Double Cone Quarterly, Fall Equinox, volume VII, Number 3 (2004)
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