SAN FRANCISCO 1906
Damage at Union Square. Photo courtesy
of the Museum of the City of San Francisco.
The San Francisco earthquake occurred at
5:12 A.M. on April 18, 1906. The source was a rupture of the San
Andreas Fault. The duration of severe shaking was about 40 seconds,
according to Professor Alexander McAdie who experienced the earthquake
Reference sources give magnitude estimates
ranging from 7.7 to 8.25. Note that there are actually several
different magnitude scales.
A "Ewing" three-component seismograph
at Lick Observatory on Mt. Hamilton made a partial recording of
the 1906 San Francisco earthquake. The earthquake amplitude was
so severe that it exceeded the range capability of this seismograph.
The Ewing seismograph was based on pendulum motion.
BUILDING DAMAGE FROM EARTHQUAKE
The earthquake damaged many buildings.
The Valencia Hotel was a four-story wooden building which collapsed
into its own basement.
The luxurious Palace Hotel shed its rear
wall but was otherwise undamaged. It had been built in 1875 to
Many people died in the earthquake and
in the fires which followed. Death toll estimates range from 700
to 3000. For example, Bruce Bolt gives a number of 700 in Reference
Fire Chief Engineer Dennis T. Sullivan
was mortally wounded when a chimney of the California Theater
and hotel crashed through the fire station in which he was living
at 410-412 Bush St.
The fires resulted from ruptured gas lines.
Water mains also ruptured, sending geysers shooting up through
broken pavement. As a result, firemen had no water to fight the
fires. The fires raged for three days.
Fire destroyed many buildings, including
the Windsor Hotel at Fifth and Market Streets.
Fireman used dynamite to destroy some buildings
in an effort to stop the fires from spreading. The fires continued
to spread despite this action.
San Francisco was known as the "Paris
of the West" in 1906. The earthquake, however, reduced it
to a "tent city." Golden Gate Park became a refugee
The area around the U.S. Mint building
became a refugee village because Superintendent Frank Leach installed
two pipes from the Mint's artesian well after the fire to provide
fresh water to the homeless.
Damage cost estimates range from $400 million
to $524 million.
The 1906 San Francisco earthquake was by
far the worst U.S. earthquake in terms of death toll, even using
the lower estimate of 700. The worst U.S. earthquake in terms
of magnitude, however, was the 1964 Alaskan earthquake.
The San Francisco earthquake has become
a benchmark by which other earthquakes are judged. For example,
scientists discovered sunquakes using data from the SOHO spacecraft.
Specifically, the spacecraft recorded a solar flare on July 9,
1996. This flare generated a quake that contained about 40,000
times the energy released in the 1906 San Francisco earthquake.
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