Geoscience Reference
In-Depth Information
trusted repositories of knowledge about environmental risk. In her study
of the “avalanche country” of western north America in this period, Di-
Stefano shows that railway men were regularly called on as expert witnesses
to determine whether or not damages caused by an avalanche could have
been prevented. Her research identifies an unfamiliar moment in the tran-
sition to the “risk society”—before environmental risk became a matter of
abstract, quantitative expertise.
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Southern California's engineers had a great deal of experience with seis-
mic faults; the question was what they would do with it. In the aftermath
of 1906, structural engineers and architects had sent the public mixed mes-
sages about the lessons of the San Francisco earthquake. Some lent credence
to the state's boosters by attributing damage to the fires, or simply to shoddy
workmanship.
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In the face of these tendencies, the SSA helped redirect the
seismic knowledge of California's engineers toward disaster mitigation.
those involved with mining and the construction of dams and reservoirs of-
ten had the keenest sense for locating faults and estimating seismic hazard.
Within weeks of the Los Angeles earthquake of 16 July 1920, the South-
ern California section of the American Institute of Mining engineers met
to discuss the earthquake threat. the meeting was organized by Ralph Ar-
nold, a former Branner student whose research on the California oil fields
had turned a nice profit. the featured speaker was William Mulholland, the
chief engineer of the Los Angeles aqueduct. Back in 1906 Mulholland had
downplayed seismic hazard. earthquakes threatened nothing “beyond the
possibility of repair in reasonable time and at moderate cost.” He cheered
the residents of Los Angeles who would take “their chances on earthquakes
or other abnormal though seemingly inevitable happenings, rather than
see the welfare of this fair country languish from lack of water.”
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In 1920,
however, Mulholland struck a far more cautious note. He began by explain-
ing that what he had to share were “observations not made in a scientific
way at all, but the mere observations of a practical engineer, accustomed to
stresses and strains in structures . . . the talk of a layman, pure and simple.”
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His knowledge came from long experience with building and maintaining
the city's waterways. He had “known for many years of the existence of a
fault or fold of the crust [by Inglewood]. . . . Along that hill or ridge the first
earthquake I experienced in California occurred . . . in 1878. I was working
at that time in a sewer pipe works near Santa Monica.” the 1878 shock had
been similar to that of 1920, Mulholland recalled, and in the intervening
years he had felt “four similar shocks” on this same ridge. In 1918, Mulhol-
land had built a water tank there. “When I constructed that tank, I knew the
seismological character of the country, and I kept telling my young engineer
