Everything about 1906 San Francisco Earthquake totally explained
The
San Francisco earthquake of 1906 was a major
earthquake that struck
San Francisco,
California and the coast of
northern California at 5:12 A.M. on Wednesday,
April 18 1906. The most widely accepted estimate for the magnitude of the earthquake is a
moment magnitude (M
w) of 7.8; however, other values have been proposed from 7.7 to as high as 8.3. The main shock
epicenter occurred offshore about 2 miles (3 km) from the city, near
Mussel Rock. It ruptured along the
San Andreas Fault both northward and southward for a total length of 296 miles (477 km). Shaking was felt from
Oregon to
Los Angeles, and inland as far as central
Nevada. The earthquake and resulting fire is remembered as one of the worst natural disasters in the history of the
United States. The death toll, estimated to be above 3,000
from the earthquake and resulting fire represents the greatest loss of life from a natural disaster in California's history. The economic impact has been compared with the more recent
Hurricane Katrina disaster.
Geology
The 1906 San Francisco earthquake was caused by a rupture 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 (1,300 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 show displacements of up to 28 feet (8.5 m).
A strong
foreshock preceded the mainshock by about 20 to 25 seconds. The strong shaking of the main shock lasted about 42 seconds. The shaking intensity as described on the
Modified Mercalli intensity scale reached VIII in San Francisco and up to IX in areas to the north like Santa Rosa where destruction was almost complete.
There were decades of minor earthquakes - more than at any other time in the historical record for northern California - before the 1906 quake. Widely previously interpreted as precursory activity to the 1906 earthquake, they've been found to have a strong seasonal pattern and were found to be due to large seasonal sediment loads in coastal bays that overlie faults as a result of the erosion caused by "hydraulic mining" in the later years of the
California Gold Rush.
Subsequent fires
As damaging as the earthquake and its
aftershocks were, the fires that burned out of control afterward were much more destructive. It has been estimated that as much as 90% of the total destruction was a result from the subsequent fires. Due to the nearly universal practice of
insurers to indemnify San Francisco properties from fire but not earthquake damage, most damage within the city was blamed on the fires. It is probable, due to the extreme magnitude of the earthquake and the poor buildings standards of the time, that a majority of structures destroyed that day were initially destroyed from the movement of the earth before succumbing to fire. 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 evacuees. Worst of all, many were set when
firefighters untrained in the use of
dynamite attempted to dynamite buildings to create
firebreaks, which resulted in the destruction of more than half of buildings that would have otherwise survived. The fire chief, who would have been responsible, had died in the initial quake. The dynamited buildings themselves often caught fire. 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. This effort was futile, as wealthier citizens of the city were burdened with the cost of repairing an estimated 80% of the city. 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 wouldn't get their insurance on buildings damaged by the earthquake unless they were damaged by fire."
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 wasn't 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 extra-wide 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 their shortcomings, these strategies did eventually prove effective in stopping the fire from spreading westward (beyond the extra-wide Van Ness Avenue) to the remaining half of the city.
One landmark building lost in the fire was the
Palace Hotel, subsequently rebuilt, which had many famous visitors, including royalty and celebrated performers. It was constructed in
1875 primarily financed by Bank of California co-founder
William Ralston, the "man who built San Francisco". In April 1906, the world's greatest tenor,
Enrico Caruso, and members of the
Metropolitan Opera Company came to San Francisco to give a series of performances at the Tivoli Opera House. The night after Caruso's performance in
Carmen, the tenor was awakened in the early morning in his Palace Hotel suite by a strong jolt. Clutching an autographed photo of President
Theodore Roosevelt, Caruso made an effort to get out of the city, first by boat and then by train, and vowed never to return to San Francisco. He kept his word. The Metropolitan Opera Company lost all of the sets and costumes it had brought to the earthquake and ensuing fires.
Some of the greatest losses from fire were in scientific
laboratories.
Alice Eastwood, the Curator of
Botany at the
California Academy of Sciences in San Francisco, is credited with saving nearly 1,500 specimens, including the entire type specimen collection for a newly discovered and extremely rare species, before the remainder of the largest botanical collection in the western United States was consumed by fire. The entire laboratory and all the records of
Benjamin R. Jacobs, a
biochemist who was researching the
nutrition of everyday foods, was lost. Another treasure lost in the fires was the original California flag used in the 1846 Bear Flag Revolt at Sonoma, which at the time was being stored in a state building in San Francisco.
The army's role in the aftermath
The city interim
fire chief (the original one was killed when the earthquake first struck) sent an urgent request to the
Presidio, an Army post on the edge of the stricken city, for
dynamite. Brigadier General
Frederick Funston, commander of 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 Mayor Schmitz of his decision to assist, and then ordered Army troops from as far away as
Angel Island to mobilize and come into the City. Explosives were ferried across the Bay from the California Powder Works in what is now
Hercules.
Martial law was never declared, however, and troops took guidance from the City's civilian administrators.
During the first few days, soldiers provided valuable services patrolling streets to discourage looting and guarding buildings such as the
US 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 Funston's superior, Major General
Adolphus Greely, Commanding Officer, Pacific Division, 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.
On
April 18, in response to riots among evacuees and looting, Mayor Schmitz issued and ordered posted a proclamation that "The Federal Troops, the members of the Regular
Police Force and all Special Police Officers have been authorized by me to KILL any and all persons found engaged in Looting or in the Commission of Any Other Crime." It is estimated that as many as 500 people were shot dead in the city, many of whom, it has been suggested, were not looting at all, but were attempting to save their own possessions from the advancing fire. In addition, accusations of soldiers themselves engaging in looting also surfaced.
Relocation and housing of displaced
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. The cottages cost on average $100-741 to put up. The $2 monthly rents went towards the full purchase price of $50. Most of the shacks have been destroyed, but a small number survived. One of the modest 720 sq ft homes was recently purchased for more than $600,000.
Aftermath and reconstruction
Property losses from the disaster have been estimated to be more than $400 million. An insurance industry source tallies insured losses at $235 million (equivalent to $5.1 billion in 2006 dollars).
Political and business leaders strongly downplayed the effects of the earthquake, fearing loss of outside investment in the city. In his first public statement, California governor
George C. Pardee emphasized the need to rebuild quickly: "this isn't the first time that San Francisco has been destroyed by fire, I've not the slightest doubt that the City by the Golden Gate will be speedily rebuilt, and will, almost before we know it, resume her former great activity." The earthquake itself isn't even mentioned in the statement. Fatality and monetary damage estimates were manipulated. In one of the most blatant attempts to cover up the realities of the earthquake, one of the photographs circulated around the country has been shown by forensic image analyst George Reid to have been altered as much as 30% to downplay the damage.
In the rush to rebuild the city, building standards were in fact lowered instead of strengthened "by upwards of 50%" according to historian Robert Hansen. Part of the rush to rebuild was the desire to be ready for an
international exposition set to be hosted in 1915, and indeed by that year there was almost no visible damage to be seen in the city. The total disregard to earthquake safety plagues the city today, as a majority of buildings standing in the city today were built in the first half of the 20th century. Incredibly, it has been suggested that building standards didn't reach even 1906 levels until the 1950s. A detailed analysis of the city today estimates that an earthquake even less powerful than the 1906 quake would completely destroy many sections of the city and result in thousands of deaths.
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. 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.
The earthquake was also responsible for the development of the
Pacific Heights neighborhood. The immense power of the earthquake had destroyed almost all of the mansions on
Nob Hill except for the Flood Mansion. As a result, the wealthy looked westward where the land was cheap and relatively undeveloped, and where there were better views and a consistently warmer climate. In the years after the war, the "money" on Nob Hill migrated to Pacific Heights, where it has remained to this day.
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.
International assistance and insurance payments
During the first few days after news of the disaster reached the rest of the world, relief efforts reached over $5,000,000.
London, England, had raised hundreds of thousands of dollars. Individual citizens and businesses donated large sums of money for the relief effort:
Standard Oil gave $100,000;
Andrew Carnegie gave $100,000; the Dominion of
Canada made a special appropriation of $100,000 and even the
Bank of Canada in
Toronto gave $25,000. The US government quickly voted for one million dollars in supplies which were immediately rushed to the area. These relief efforts, however, were not nearly enough to get families on their feet again, and consequently the burden was placed on wealthier members of the city, who were reluctant to assist in the rebuilding of homes they were not responsible for. Additional funds were taken from racial minorities in the city, who were to be deported in the near future.
Insurance companies, faced with staggering claims of $250 million, paid out between $235 million and $265 million on policyholders' claims, chiefly for fire damage, since shake damage from earthquakes was excluded from coverage under most policies. At least 137 insurance companies were directly involved and another 17 as reinsurers. Many insurance companies launched public relations campaigns right after the earthquake, claiming that they'd paid all policyholder claims without discount - which was nothing else than their legal obligation. Some companies continue this to this day. For instance,
Lloyds of London maintains having paid more than $50 million in claims (more than $1 billion in 2005 dollars), an assertion which still needs full historical proof.
The earthquake was the worst single incident for the insurance industry before the
September 11, 2001 attacks. After the 1906 earthquake, a global discussion arose concerning a legally flawless exclusion of the earthquake hazard from fire insurance contracts. It was pressed ahead mainly by re-insurers. Their aim was the globally uniform solution of the problem of earthquake hazard in fire insurance contracts. Until 1910, a few countries, especially in Europe, followed the call for an exclusion of the earthquake hazard from all fire insurance contracts. In the US, however, the question was discussed differently. But the traumatized public reacted with fierce opposition. On
August 1 1909, the
California Senate enacted the California Standard Form of Fire Insurance Policy, which didn't contain any earthquake clause. Thus the state decided that insurers would have to pay again if another earthquake was followed by fires. Other earthquake-endangered countries followed the California example. The insurance payments heavily affected the international financial system. Gold transfers from European insurance companies to policyholders in San Francisco led to a rise in interest rates, subsequently to a lack of available loans and finally to the Knickerbocker Crisis of October 1907 and a recession of the US economy.
Centennial commemorations
The 1906 Centennial Alliance was 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 were part of the commemorations. The
USGS Earthquake Hazards Program issued a series of Internet documents, and the tourism industry promoted the 100th anniversary as well.
Analysis
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.
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 of Bay landfill 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.
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