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99-487: The International Seismological Summary (ISS) is a global earthquake catalog covering the period from 1918 to 1963. The need for an international exchange of seismology data was recognised by John Milne , who in 1899 began collating and publishing data from 35 observatories from around the world. Following his death in 1913, the ISS was founded at the end of the war in 1918 to continue the work. Since 1964 it has been published as

198-690: A backdoor to the Chinese Exclusion Act , 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 James C. Flood Mansion . Others that had not been destroyed were dynamited by the Army forces aiding the firefighting efforts in attempts to create firebreaks. As one indirect result,

297-526: 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". 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 ,

396-540: A makeshift tent city in Golden Gate Park and were treated by the faculty of the Affiliated Colleges. This brought the school, which until then was located on the western outskirts of the city, in contact with significant population and fueled the commitment of the school towards civic responsibility and health care, increasing the momentum towards the construction of its own health facilities. In April 1907, one of

495-501: A mantle of silicates, surrounding a core of iron. In 1906 Richard Dixon Oldham identified the separate arrival of P waves , S-waves and surface waves on seismograms and found the first clear evidence that the Earth has a central core. In 1909, Andrija Mohorovičić , one of the founders of modern seismology, discovered and defined the Mohorovičić discontinuity . Usually referred to as

594-399: A month after the event. The first observations of normal modes were made in the 1960s as the advent of higher fidelity instruments coincided with two of the largest earthquakes of the 20th century the 1960 Valdivia earthquake and the 1964 Alaska earthquake . Since then, the normal modes of the Earth have given us some of the strongest constraints on the deep structure of the Earth. One of

693-412: A near-surface explosion, and are much weaker for deep earthquake sources. Both body and surface waves are traveling waves; however, large earthquakes can also make the entire Earth "ring" like a resonant bell. This ringing is a mixture of normal modes with discrete frequencies and periods of approximately an hour or shorter. Normal mode motion caused by a very large earthquake can be observed for up to

792-449: A particular location within a particular time-span, and they are routinely used in earthquake engineering . Public controversy over earthquake prediction erupted after Italian authorities indicted six seismologists and one government official for manslaughter in connection with a magnitude 6.3 earthquake in L'Aquila, Italy on April 5, 2009 . A report in Nature stated that the indictment

891-564: A result of the erosion caused by hydraulic mining in the later years of the California Gold Rush . For years, the epicenter of the quake was assumed to be near the town of Olema , in the Point Reyes area of Marin County , due to local earth displacement measurements. In the 1960s, a seismologist at UC Berkeley proposed that the epicenter was more likely offshore of San Francisco, to

990-518: A special meeting in L'Aquila the week before the earthquake occurred, scientists and officials were more interested in pacifying the population than providing adequate information about earthquake risk and preparedness. In locations where a historical record exists it may be used to estimate the timing, location and magnitude of future seismic events. There are several interpretative factors to consider. The epicentres or foci and magnitudes of historical earthquakes are subject to interpretation meaning it

1089-509: A time when the science of seismology was blossoming. Although the impact of the earthquake on San Francisco was the most famous, the earthquake also inflicted considerable damage on several other cities. These include San Jose and Santa Rosa , the entire downtown of which was essentially destroyed. As damaging as the earthquake and its aftershocks were, the fires that burned out of control afterward were far more destructive. It has been estimated that at least 80%, and at most over 95%, of

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1188-569: A very short time frame in a seismic cycle . Engineering seismology is the study and application of seismology for engineering purposes. It generally applied to the branch of seismology that deals with the assessment of the seismic hazard of a site or region for the purposes of earthquake engineering. It is, therefore, a link between earth science and civil engineering . There are two principal components of engineering seismology. Firstly, studying earthquake history (e.g. historical and instrumental catalogs of seismicity) and tectonics to assess

1287-595: A woman who lit her stove to prepare breakfast, unaware of the badly damaged chimney, destroying a 30-block area, including a college, the Hall of Records and City Hall. Some of the fires were started when San Francisco Fire Department firefighters, untrained in the use of dynamite , attempted to demolish buildings to create firebreaks . The dynamited buildings often caught fire. The city's fire chief, Dennis T. Sullivan , who would have been responsible for coordinating firefighting efforts, had died from injuries sustained in

1386-538: Is called a seismograph . Networks of seismographs continuously record ground motions around the world to facilitate the monitoring and analysis of global earthquakes and other sources of seismic activity. Rapid location of earthquakes makes tsunami warnings possible because seismic waves travel considerably faster than tsunami waves. Seismometers also record signals from non-earthquake sources ranging from explosions (nuclear and chemical), to local noise from wind or anthropogenic activities, to incessant signals generated at

1485-550: Is characterized by mainly lateral motion in a dextral sense, where the western (Pacific) plate moves northward relative to the eastern (North American) plate. This fault runs the length of California from the Salton Sea in the south to Cape Mendocino in the north, a distance of about 810 miles (1,300 km). The maximum observed surface displacement was about 20 feet (6 m); geodetic measurements show displacements of up to 28 feet (8.5 m). The 1906 earthquake preceded

1584-450: 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 destroyed in the fire. The entire laboratory and all the records of Benjamin R. Jacobs , a biochemist who was researching the nutrition of everyday foods, were destroyed. The original California flag used in

1683-427: Is equivalent to $ 10.2 billion in 2023 dollars. An insurance industry source tallies insured losses at $ 235 million, the equivalent to $ 5.97 billion in 2023 dollars. Political and business leaders strongly downplayed the effects of the earthquake, fearing loss of outside investment in the city which was badly needed to rebuild. In his first public statement, California Governor George Pardee emphasized

1782-413: Is possible that 5–6 Mw earthquakes described in the historical record could be larger events occurring elsewhere that were felt moderately in the populated areas that produced written records. Documentation in the historic period may be sparse or incomplete, and not give a full picture of the geographic scope of an earthquake, or the historical record may only have earthquake records spanning a few centuries,

1881-461: Is still uncertain, but various reports presented a range of 700–3,000+. In 2005, the city's Board of Supervisors voted unanimously in support of a resolution written by novelist James Dalessandro ("1906") and city historian Gladys Hansen ("Denial of Disaster") to recognize the figure of 3,000+ as the official total. Most of the deaths occurred within San Francisco, but 189 were reported elsewhere in

1980-562: Is talking of it this afternoon, and no one is in the least degree dismayed. I have talked and listened in two clubs, watched people in cars and in the street, and one man is glad that Chinatown will be cleared out for good; another's chief solicitude is for Millet 's Man with a Hoe . 'They'll cut it out of the frame,' he says, a little anxiously. 'Sure.' But there is no doubt anywhere that San Francisco can be rebuilt, larger, better, and soon. Just as there would be none at all if all this New York that has so obsessed me with its limitless bigness

2079-519: The Bank of Canada in Ottawa gave $ 25,000. The U.S. government quickly voted for one million dollars in relief supplies which were immediately rushed to the area, including supplies for food kitchens and many thousands of tents that city dwellers would occupy the next several years. These relief efforts were not enough to get families on their feet again, and consequently the burden was placed on wealthier members of

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2178-595: The California Senate enacted the California Standard Form of Fire Insurance Policy, which did not 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 1906 Centennial Alliance was set up as a clearing-house for various centennial events commemorating

2277-559: The Imperial Valley area, which culminated in an earthquake of about 6.1 M I   at 16:30 PST on April 18, 1906. Another event of this type occurred at 12:31 PST on April 19, 1906, with an estimated magnitude of about 5.0 M I  , and an epicenter beneath Santa Monica Bay . Early death counts ranged from 375 to over 500. However, hundreds of fatalities in Chinatown went ignored and unrecorded. The total number of deaths

2376-490: 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. Under the command of Funston's superior, Major General Adolphus Greely , Commanding Officer of the Pacific Division, over 4,000 federal troops saw service during

2475-451: The VAN method . Most seismologists do not believe that a system to provide timely warnings for individual earthquakes has yet been developed, and many believe that such a system would be unlikely to give useful warning of impending seismic events. However, more general forecasts routinely predict seismic hazard . Such forecasts estimate the probability of an earthquake of a particular size affecting

2574-561: The "Moho discontinuity" or the " Moho ," it is the boundary between the Earth 's crust and the mantle . It is defined by the distinct change in velocity of seismological waves as they pass through changing densities of rock. In 1910, after studying the April 1906 San Francisco earthquake , Harry Fielding Reid put forward the " elastic rebound theory " which remains the foundation for modern tectonic studies. The development of this theory depended on

2673-622: The "man who built San Francisco". In April 1906, the tenor Enrico Caruso and members of the Metropolitan Opera Company came to San Francisco to give a series of performances at the Grand 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

2772-522: The 1846 Bear Flag Revolt at Sonoma , which at the time was being stored in a state building in San Francisco, was also destroyed in the fire. The city's fire chief, Dennis T. Sullivan, was gravely injured when the earthquake first struck and later died from his injuries. The interim fire chief sent an urgent request to the Presidio, a United States Army post on the edge of the stricken city, for dynamite. General Frederick Funston had already decided that

2871-450: The 22nd Infantry and other military units involved in the emergency. Ord later wrote a long letter to his mother on April 20 regarding Schmitz's "Shoot-to-Kill" order and some "despicable" behavior of certain soldiers of the 22nd Infantry who were looting. He also made it clear that the majority of soldiers served the community well. Property losses from the disaster have been estimated to be more than $ 400 million in 1906 dollars. This

2970-677: The Bay Area; nearby cities such as Santa Rosa and San Jose also suffered severe damage. Between 227,000 and 300,000 people were left homeless out of a population of about 410,000; half of those who evacuated fled across the bay to Oakland and Berkeley . Newspapers described Golden Gate Park , the Presidio, the Panhandle and the beaches between Ingleside and North Beach as covered with makeshift tents. More than two years later, many of these refugee camps were still in operation. The earthquake and fire left long-standing and significant pressures on

3069-489: The Chinese population and export Chinatown (and other poor populations) to the edge of the county where the Chinese could still contribute to the local taxbase. The Chinese occupants had other ideas and prevailed instead. Chinatown was rebuilt in the newer, modern, Western form that exists today. The destruction of City Hall and the Hall of Records enabled thousands of Chinese immigrants to claim residency and citizenship, creating

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3168-629: The Federal Government of the United States had not conducted the serious studies that were needed to gather data about earthquakes on the west coast. He said public discussion was being stifled by fears that acknowledgement of earthquakes would drive away business and investors, and that geologists were told not to gather information about the 1906 earthquake, and certainly to not publish it. Some people went as far as to deny that an earthquake had happened. Branner argued that preparation for earthquakes

3267-617: The Highlanders (soon to be the Yankees) and the Philadelphia Athletics to raise money for quake survivors. William James , the pioneering American psychologist, was teaching at Stanford at the time of the earthquake and traveled into San Francisco to observe first-hand its aftermath. He was most impressed by the positive attitude of the survivors and the speed with which they improvised services and created order out of chaos. This formed

3366-621: The International Seismological Centre Bulletin. This seismology article is a stub . You can help Misplaced Pages by expanding it . Seismology Scholarly interest in earthquakes can be traced back to antiquity. Early speculations on the natural causes of earthquakes were included in the writings of Thales of Miletus ( c.  585 BCE ), Anaximenes of Miletus ( c.  550 BCE ), Aristotle ( c.  340 BCE ), and Zhang Heng (132 CE). In 132 CE, Zhang Heng of China's Han dynasty designed

3465-488: The arts colony reputation that continues today. The 1908 Lawson Report, a study of the 1906 quake led and edited by Professor Andrew Lawson of the University of California, showed that the 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 and occurred at

3564-529: The basis of the chapter "On some Mental Effects of the Earthquake" in his book Memories and Studies . H. G. Wells had just arrived in New York on his first visit to America when he learned of the San Francisco earthquake. What struck him about the reaction of those around him was that "it does not seem to have affected any one with a sense of final destruction, with any foreboding of irreparable disaster. Every one

3663-595: The behaviour and causation of earthquakes. The earliest responses include work by John Bevis (1757) and John Michell (1761). Michell determined that earthquakes originate within the Earth and were waves of movement caused by "shifting masses of rock miles below the surface". In response to a series of earthquakes near Comrie in Scotland in 1839, a committee was formed in the United Kingdom in order to produce better detection methods for earthquakes. The outcome of this

3762-463: The buildings was renovated for outpatient care with 75 beds. This created the need to train nursing students, and the UC Training School for Nurses was established, adding a fourth professional school to the Affiliated Colleges. The grandeur of citywide reconstruction schemes required investment from Eastern monetary sources, hence the spin and de-emphasis of the earthquake, the promulgation of

3861-597: 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. 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

3960-550: The city was destroyed. The event is remembered as the deadliest earthquake in the history of the United States . The death toll remains the greatest loss of life from a natural disaster in California's history and high on the lists of American disasters. The San Andreas Fault is a continental transform fault that forms part of the tectonic boundary between the Pacific plate and the North American plate . The strike-slip fault

4059-485: The city, first by boat and then by train, and vowed never to return to San Francisco. Caruso died in 1921, having remained true to his word. The Metropolitan Opera Company lost all of its traveling sets and costumes in 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,

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4158-566: The city, who were reluctant to assist in the rebuilding of homes they were not responsible for. All residents were eligible for daily meals served from a number of communal soup kitchens, and citizens as far away as Idaho and Utah were known to send daily loaves of bread to San Francisco as relief supplies were coordinated by the railroads. Insurance companies, faced with staggering claims of $ 250 million, paid out between $ 235 million and $ 265 million on policyholders' claims, often for fire damage only, since shake damage from earthquakes

4257-682: The coast of Northern California was struck by a major earthquake with an estimated moment magnitude of 7.9 and a maximum Mercalli intensity of XI ( Extreme ). High-intensity shaking was felt from Eureka on the North Coast to the Salinas Valley , an agricultural region to the south of the San Francisco Bay Area . Devastating fires soon broke out in San Francisco and lasted for several days. More than 3,000 people died, and over 80% of

4356-532: The considerable progress of earlier independent streams of work on the behavior of elastic materials and in mathematics. An early scientific study of aftershocks from a destructive earthquake came after the January 1920 Xalapa earthquake . An 80 kg (180 lb) Wiechert seismograph was brought to the Mexican city of Xalapa by rail after the earthquake. The instrument was deployed to record its aftershocks. Data from

4455-606: 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 . Over a period of 60 years, the city had become the financial, trade, and cultural center of the West , operating the busiest port on the West Coast. It was the "gateway to the Pacific", through which growing U.S. economic and military power

4554-520: The development of the Richter scale by three decades. The most widely accepted estimate for the magnitude of the quake on the modern moment magnitude scale is 7.9; values from 7.7 to as high as 8.3 have been proposed. According to findings published in the Journal of Geophysical Research , severe deformations in the Earth's crust took place both before and after the earthquake's impact. Accumulated strain on

4653-512: The earth to a resolution of several hundred kilometers. This has enabled scientists to identify convection cells and other large-scale features such as the large low-shear-velocity provinces near the core–mantle boundary . Forecasting a probable timing, location, magnitude and other important features of a forthcoming seismic event is called earthquake prediction . Various attempts have been made by seismologists and others to create effective systems for precise earthquake predictions, including

4752-674: The earthquake strongly suggests that the rupture along the San Andreas Fault was about 310 miles (500 km) in length, in agreement with observed intensity data. The available seismological data support a significantly shorter rupture length, but these observations can be reconciled by allowing propagation at speeds above the S-wave velocity ( supershear ). Supershear propagation has now been recognized for many earthquakes associated with strike-slip faulting. In 2019, using an old photograph and an eyewitness account, researchers were able to refine

4851-765: The earthquake when it became too much trouble for them. Del Monte and another survivor, Rose Cliver (1902–2012), then 106, attended the earthquake reunion celebration on April 18, 2009, the 103rd anniversary of the earthquake. Nancy Stoner Sage (1905–2010) died, aged 105, in Colorado just three days short of the 104th anniversary of the earthquake on April 18, 2010. Del Monte attended the event at Lotta's Fountain in 2010. 107-year-old George Quilici (1905–2012) died in May 2012, and 113-year-old Ruth Newman (1901–2015) in July 2015. William Del Monte (1906–2016), who died 11 days shy of his 110th birthday,

4950-523: 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. Eleven survivors of the 1906 earthquake attended the centennial commemorations in 2006, including Irma Mae Weule (1899–2008), who

5049-725: The earthquakes that could occur in a region and their characteristics and frequency of occurrence. Secondly, studying strong ground motions generated by earthquakes to assess the expected shaking from future earthquakes with similar characteristics. These strong ground motions could either be observations from accelerometers or seismometers or those simulated by computers using various techniques, which are then often used to develop ground motion prediction equations (or ground-motion models) [1] . Seismological instruments can generate large amounts of data. Systems for processing such data include: 1906 San Francisco earthquake At 05:12 AM Pacific Standard Time on Wednesday, April 18, 1906,

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5148-428: The emergency. Police officers, firefighters, and soldiers would regularly commandeer passing civilians for work details to remove rubble and assist in rescues. On July 1, 1906, non-military 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,

5247-455: The faults in the system was relieved during the earthquake, which is the supposed cause of the damage along the 280-mile-long (450 km) segment of the San Andreas plate boundary. The 1906 rupture propagated both northward and southward for a total of 296 miles (476 km). Shaking was felt from Oregon to Los Angeles, and as far inland as central Nevada . A strong foreshock preceded

5346-441: The fire had the effect of increasing the share of land used for nonresidential purposes: "Overall, relative to unburned blocks, residential land shares on burned blocks fell while nonresidential land shares rose by 1931. The study also provides insight into what held the city back from making these changes before 1906: the presence of old residential buildings. In reconstruction, developers built relatively fewer of these buildings, and

5445-456: The first attempts at the scientific study of earthquakes followed the 1755 Lisbon earthquake. Other notable earthquakes that spurred major advancements in the science of seismology include the 1857 Basilicata earthquake , the 1906 San Francisco earthquake, the 1964 Alaska earthquake , the 2004 Sumatra-Andaman earthquake , and the 2011 Great East Japan earthquake . Seismic waves produced by explosions or vibrating controlled sources are one of

5544-473: The first few days after news of the disaster reached the rest of the world, relief efforts reached over $ 5,000,000, equivalent to $ 169,560,000 in 2023. London raised hundreds of thousands of dollars. Individual citizens and businesses donated large sums of money for the relief effort: Standard Oil and Andrew Carnegie each gave $ 100,000; the Dominion of Canada made a special appropriation of $ 100,000; and even

5643-441: The first few days of near M 5 or greater occurred near Santa Cruz at 14:28 PST on April 18, with a magnitude of about 4.9 M I . The largest aftershock happened at 01:10 PST on April 23, west of Eureka with an estimated magnitude of about 6.7 M I  , with another of the same size more than three years later at 22:45 PST on October 28 near Cape Mendocino. Remotely triggered events included an earthquake swarm in

5742-578: The first known seismoscope . In the 17th century, Athanasius Kircher argued that earthquakes were caused by the movement of fire within a system of channels inside the Earth. Martin Lister (1638–1712) and Nicolas Lemery (1645–1715) proposed that earthquakes were caused by chemical explosions within the Earth. The Lisbon earthquake of 1755 , coinciding with the general flowering of science in Europe , set in motion intensified scientific attempts to understand

5841-415: The first waves to appear on a seismogram as they are the fastest moving waves through solids. S-waves are transverse waves that move perpendicular to the direction of propagation. S-waves are slower than P-waves. Therefore, they appear later than P-waves on a seismogram. Fluids cannot support transverse elastic waves because of their low shear strength, so S-waves only travel in solids. Surface waves are

5940-473: The foundation of modern instrumental seismology and carried out seismological experiments using explosives. He is also responsible for coining the word "seismology." In 1889 Ernst von Rebeur-Paschwitz recorded the first teleseismic earthquake signal (an earthquake in Japan recorded at Pottsdam Germany). In 1897, Emil Wiechert 's theoretical calculations led him to conclude that the Earth's interior consists of

6039-432: The global seismographic monitoring has been for the detection and study of nuclear testing . Because seismic waves commonly propagate efficiently as they interact with the internal structure of the Earth, they provide high-resolution noninvasive methods for studying the planet's interior. One of the earliest important discoveries (suggested by Richard Dixon Oldham in 1906 and definitively shown by Harold Jeffreys in 1926)

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6138-507: The initial quake. In total, the fires burned for four days and nights. Most of the destruction in the city was attributed to the fires, since widespread practice by insurers was to indemnify San Francisco properties from fire but not from earthquake damage. Some property owners deliberately set fire to damaged properties to claim them on their insurance. Captain Leonard D. Wildman of the U.S. Army Signal Corps reported that he "was stopped by

6237-406: The interior of the materials; surface waves that travel along surfaces or interfaces between materials; and normal modes , a form of standing wave. There are two types of body waves, pressure waves or primary waves (P-waves) and shear or secondary waves ( S waves ). P-waves are longitudinal waves that involve compression and expansion in the direction that the wave is moving and are always

6336-568: 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 Trust Company crisis of October 1907 which led to the Panic of 1907 . After the 1906 earthquake, global discussion arose concerning a legally flawless exclusion of the earthquake hazard from fire insurance contracts. It

6435-502: 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 during the aftermath of the earthquake. For example, real estate investors and other land owners were against the idea because of 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

6534-410: 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 . Limestone used to reconstruct city buildings was quarried at the nearby Rockaway Quarry . City fathers likewise attempted at the time to eliminate

6633-477: The location of the hypocenter of the earthquake as offshore from San Francisco or near San Juan Bautista , confirming previous estimates. The most important characteristic of the shaking intensity noted in Andrew 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

6732-483: The main shock by about 20 to 25 seconds. The strong shaking of the main shock lasted about 42 seconds. There were decades of minor earthquakes – more than at any other time in the historical record for northern California – before the 1906 quake. Previously interpreted as precursory activity to the 1906 earthquake, they have been found to have a strong seasonal pattern and are now believed to be caused by large seasonal sediment loads in coastal bays that overlie faults as

6831-434: The majority of the reduction came through single-family houses. Also, aside from merely expanding nonresidential uses in many neighborhoods, the fire created economic opportunities in new areas, resulting in clusters of business activity that emerged only in the wake of the disaster. These effects of the fire still remain today, and thus large shocks can be sufficient catalysts for permanently reshaping urban settings." During

6930-628: 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". Accusations of soldiers engaging in looting also surfaced. Retired Captain Edward Ord of the 22nd Infantry Regiment was appointed a special police officer by Schmitz and liaised with Greely for relief work with

7029-506: The need to rebuild quickly: "This is not the first time that San Francisco has been destroyed by fire, I have 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 is not even mentioned in the statement. Fatality and monetary damage estimates were manipulated. Almost immediately after

7128-561: The northwest of the Golden Gate . The most recent analyses support an offshore location for the epicenter, although significant uncertainty remains. An offshore epicenter is supported by the occurrence of a local tsunami recorded by a tide gauge at the San Francisco Presidio ; the wave had an amplitude of approximately 3 inches (7.6 cm) and an approximate period of 40–45 minutes. Analysis of triangulation data before and after

7227-481: The ocean floor and coasts induced by ocean waves (the global microseism ), to cryospheric events associated with large icebergs and glaciers. Above-ocean meteor strikes with energies as high as 4.2 × 10 J (equivalent to that released by an explosion of ten kilotons of TNT) have been recorded by seismographs, as have a number of industrial accidents and terrorist bombs and events (a field of study referred to as forensic seismology ). A major long-term motivation for

7326-436: The ocean processes responsible for the global background seismic microseism . By the 1960s, Earth science had developed to the point where a comprehensive theory of the causation of seismic events and geodetic motions had come together in the now well-established theory of plate tectonics . Seismic waves are elastic waves that propagate in solid or fluid materials. They can be divided into body waves that travel through

7425-473: The primary methods of underground exploration in geophysics (in addition to many different electromagnetic methods such as induced polarization and magnetotellurics ). Controlled-source seismology has been used to map salt domes , anticlines and other geologic traps in petroleum -bearing rocks , faults , rock types, and long-buried giant meteor craters . For example, the Chicxulub Crater , which

7524-437: The quake (and even during the disaster), planning and reconstruction plans were hatched to quickly rebuild the city. Rebuilding funds were immediately tied up by the fact that virtually all the major banks had been sites of the conflagration, requiring a lengthy wait of seven to ten days before their fire-proof vaults could cool sufficiently to be safely opened. The Bank of Italy (now Bank of America ) had evacuated its funds and

7623-400: The result of P- and S-waves interacting with the surface of the Earth. These waves are dispersive , meaning that different frequencies have different velocities. The two main surface wave types are Rayleigh waves , which have both compressional and shear motions, and Love waves , which are purely shear. Rayleigh waves result from the interaction of P-waves and vertically polarized S-waves with

7722-416: The seismograph would eventually determine that the mainshock was produced along a shallow crustal fault. In 1926, Harold Jeffreys was the first to claim, based on his study of earthquake waves, that below the mantle, the core of the Earth is liquid. In 1937, Inge Lehmann determined that within Earth's liquid outer core there is a solid inner core . In 1950, Michael S. Longuet-Higgins elucidated

7821-571: The situation required the use of federal troops. Telephoning a San Francisco Police Department officer, he sent word to Mayor Eugene Schmitz of his decision to assist and then ordered federal troops from nearby Angel Island to mobilize and enter the city. Explosives were ferried across the bay from the California Powder Works in what is now Hercules . During the first few days, soldiers provided valuable services like patrolling streets to discourage looting and guarding buildings such as

7920-480: The strongest shaking occurred in areas of former bay where soil liquefaction had occurred. Modern seismic-zonation practice accounts for the differences in seismic hazard posed by varying geologic conditions. The shaking intensity as described on the Modified Mercalli intensity scale reached XI ( Extreme ) in San Francisco and areas to the north like Santa Rosa where destruction was devastating. The main shock

8019-476: The surface and can exist in any solid medium. Love waves are formed by horizontally polarized S-waves interacting with the surface, and can only exist if there is a change in the elastic properties with depth in a solid medium, which is always the case in seismological applications. Surface waves travel more slowly than P-waves and S-waves because they are the result of these waves traveling along indirect paths to interact with Earth's surface. Because they travel along

8118-399: The surface of the Earth, their energy decays less rapidly than body waves (1/distance vs. 1/distance ), and thus the shaking caused by surface waves is generally stronger than that of body waves, and the primary surface waves are often thus the largest signals on earthquake seismograms . Surface waves are strongly excited when their source is close to the surface, as in a shallow earthquake or

8217-463: The total destruction was the result of the subsequent fires. Within three days, over 30 fires, caused by ruptured gas mains, destroyed approximately 25,000 buildings on 490 city blocks. The fires cost an estimated $ 350 million at the time (equivalent to $ 8.9 billion in 2023). The Ham and Eggs fire, in the morning on the 18th, at Hayes and Gough Streets, in Hayes Valley , was started by

8316-428: The tough new building codes, and subsequent reputation sensitive actions such as the official low death toll. 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

8415-418: The wealthy looked westward where the land was cheap and relatively undeveloped, and where there were better views. Constructing new mansions without reclaiming and clearing rubble simply sped attaining new homes in the tent city during the reconstruction. Reconstruction was swift, and largely completed by 1915, in time for the 1915 Panama–Pacific International Exposition which celebrated the reconstruction of

8514-401: Was able to provide liquidity in the immediate aftermath. Its president also immediately chartered and financed the sending of two ships to return with shiploads of lumber from Washington and Oregon mills which provided the initial reconstruction materials and surge. In an article written in 1913, John C. Branner, who was the first to begin study of the San Andreas fault in 1891 complained that

8613-591: Was caused by an impact that has been implicated in the extinction of the dinosaurs , was localized to Central America by analyzing ejecta in the Cretaceous–Paleogene boundary , and then physically proven to exist using seismic maps from oil exploration . Seismometers are sensors that detect and record the motion of the Earth arising from elastic waves. Seismometers may be deployed at the Earth's surface, in shallow vaults, in boreholes, or underwater . A complete instrument package that records seismic signals

8712-489: Was closed on June 30, 1908. Most of the cottages have been destroyed, but at least 30 survived. Of the remaining structures, there is a historically restored pair in the Presidio. Others have been built on as part of private homes, with a high concentration around the Bernal Heights neighborhood. One of the modest 720 sq ft (67 m ) homes was purchased in 2006 for more than $ 600,000. A 2017 study found that

8811-452: Was completed. They were painted navy blue, partly to blend in with the site and partly because the military had large quantities of navy blue 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 to build. The $ 2 monthly rents went towards the full purchase price of $ 50. The last official refugee camp

8910-677: Was excluded from coverage under most policies. At least 137 insurance companies were directly involved and another 17 as reinsurers. Twenty companies went bankrupt. Lloyd's of London reports having paid all claims in full, more than $ 50 million, thanks to the leadership of Cuthbert Heath . Insurance companies in Hartford, Connecticut , report paying every claim in full, with the Hartford Fire Insurance Company paying over $ 11 million and Aetna Insurance Company almost $ 3 million. The insurance payments heavily affected

9009-479: Was followed by many aftershocks and some remotely triggered events . As with the 1857 Fort Tejon earthquake , there were fewer aftershocks than would have been expected for a shock of that size. Very few of them were located along the trace of the 1906 rupture, tending to concentrate near the ends of the rupture or on other structures away from the San Andreas Fault, such as the Hayward Fault . The only aftershock in

9108-652: Was itself a blazing ruin. I believe these people would more than half like the situation." The earthquake was crucial in the development of the University of California, San Francisco and its medical facilities. Until 1906, the school faculty had provided care at the City-County Hospital (now the San Francisco General Hospital ), but did not have a hospital of its own. Following the 1906 San Francisco earthquake, more than 40,000 people were relocated to

9207-540: Was possible and necessary: The only way we know of to deal successfully with any natural phenomenon is to get acquainted with it, to find out all we can about it, and thus to meet it on its own grounds. That is the way mankind has succeeded thus far, and it is safe to conclude that it is the only way it will ever succeed. Eleven days after the earthquake a rare Sunday baseball game was played in New York City (which would not allow regular Sunday baseball until 1919) between

9306-461: Was pressed ahead mainly by re-insurers. Their aim: a uniform solution to insurance payouts resulting from fires caused by earthquakes. 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 U.S., the question was discussed differently. But the traumatized public reacted with fierce opposition. On August 1, 1909,

9405-484: Was projected into the Pacific and Asia. Over 80% of the city was destroyed by the earthquake and fire. Though San Francisco rebuilt quickly, the disaster diverted trade, industry, and population growth south to Los Angeles, which during the 20th century became the largest and most important urban area in the West. Many of the city's leading poets and writers retreated to Carmel-by-the-Sea where, as "The Barness", they established

9504-409: Was that the outer core of the earth is liquid. Since S-waves do not pass through liquids, the liquid core causes a "shadow" on the side of the planet opposite the earthquake where no direct S-waves are observed. In addition, P-waves travel much slower through the outer core than the mantle. Processing readings from many seismometers using seismic tomography , seismologists have mapped the mantle of

9603-663: Was the oldest survivor of the quake at the time of her death in August 2008, aged 109. Vivian Illing (1900–2009) was believed to be the second-oldest survivor at the time of her death, aged 108, leaving Herbert Hamrol (1903–2009) as the last known remaining survivor at the time of his death, aged 106. Another survivor, Libera Armstrong (1902–2007), attended the 2006 anniversary but died in 2007, aged 105. Shortly after Hamrol's death, two additional survivors were discovered. William Del Monte, then 103, and Jeanette Scola Trapani (1902–2009), 106, stated that they stopped attending events commemorating

9702-415: Was the production of one of the first modern seismometers by James David Forbes , first presented in a report by David Milne-Home in 1842. This seismometer was an inverted pendulum, which recorded the measurements of seismic activity through the use of a pencil placed on paper above the pendulum. The designs provided did not prove effective, according to Milne's reports. From 1857, Robert Mallet laid

9801-711: Was widely seen in Italy and abroad as being for failing to predict the earthquake and drew condemnation from the American Association for the Advancement of Science and the American Geophysical Union . However, the magazine also indicated that the population of Aquila do not consider the failure to predict the earthquake to be the reason for the indictment, but rather the alleged failure of the scientists to evaluate and communicate risk. The indictment claims that, at

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