An Assessment of the Consequences and Preparations for a Catastrophic California Earthquake: Findin | Page 3

more destructive because of its relative
proximity to the most heavily developed regions; however, the
probability of this event is estimated to be only about 0.1 percent per
year. Smaller magnitude--and consequently less
damaging--earthquakes are anticipated with greater frequency on a
number of fault systems in California.
In either of these earthquakes, casualties could surpass the previous
single greatest loss of life in the United States due to a natural disaster,
which was about 6,000 persons killed when a hurricane and storm
surge struck the Galveston area of the Texas coast in 1900. The highest
loss of life due to earthquakes in the United States occurred in San
Francisco in 1906, when 700 people were killed. By way of
comparison (in spite of the vast differences in building design and
practices and socioeconomic systems) the devastating 1976 Tangshan
earthquake in China caused fatalities ranging from the official Chinese

Government figure of 242,000 to unofficial estimates as high as
700,000. Fortunately, building practices in the United States preclude
such a massive loss of life.
Property losses are expected to be higher than in any past earthquake in
the United States. For example, San Francisco in 1906, and Anchorage
in 1964, were both much less developed than today when they were hit
by earthquakes. And the San Fernando earthquake in 1971, was only a
moderate shock that struck on the fringe of a large urban area. Each of
these three earthquakes caused damage estimated at about $0.5 billion
in the then current dollars. Estimates of property damage for the most
probable catastrophic earthquake on the Southern San Andreas (Richter
magnitude 8+) and for the less probable but more damaging one
(Richter magnitude 7.5) on the Newport-Inglewood fault, are about $15
billion and $70 billion respectively. By comparison, tropical storm
Agnes caused the largest economic loss due to a natural disaster in the
United States to date but it amounted to only $3.5 billion (in 1972
dollars).
It should be noted, however, that substantial uncertainty exists in
casualty and property damage estimates because they are based on
experience with only moderate earthquakes in the United States (such
as the 1971 San Fernando earthquake) and experience in other
countries where buildings are generally less resistant to damage. The
uncertainty is so large that the estimated impacts could be off by a
factor of two or three, either too high or too low. Even if these lowest
estimates prevail, however, the assessment about preparedness and the
capability to respond to the disasters discussed in this report would be
substantially unchanged.
Assuming a catastrophic earthquake, a variety of secondary problems
could also be expected. Search and rescue operations--requiring heavy
equipment to move debris--would be needed to free people trapped in
collapsed buildings. It is likely that injuries, particularly those
immediately after the event, could overwhelm medical capabilities,
necessitating a system of allocating medical resources to those who
could be helped the most. Numerous local fires must be expected;

nevertheless, a conflagration such as that which followed the Tokyo
earthquake of 1923, or the San Francisco earthquake of 1906, is
improbable, unless a "Santa Ana type" wind pattern is in effect. Since
the near failure of a dam in the San Fernando, California, earthquake of
1971 (which was a moderate event), substantial progress has been made
in California to reduce the hazard from dams, in some cases through
reconstruction. For planning purposes, however, experts believe that
the failure of at least one dam should be anticipated during a
catastrophic earthquake in either the Los Angeles or San Francisco
regions.
Experience in past earthquakes, particularly the 1971 San Fernando
earthquake, has demonstrated the potential vulnerability of commercial
telephone service to earthquakes, including the possibility of damage to
switching facilities from ground shaking and rupture of underground
cables that cross faults. This is especially serious because immediately
following earthquakes, public demand for telephone services increases
drastically. This increased demand overloads the capability of the
system, even if it had not been damaged, and therefore management
action to reduce the availability of service to non-priority users and to
accommodate emergency calls is mandatory. Radio-based
communication systems, particularly those not requiring commercial
power, are relatively safe from damage, although some must be
anticipated. The redundancy of existing communication systems,
including those designed for emergency use, means that some
capability for communicating with the affected region from the outside
would almost surely exist. Restoration of service by the commercial
carriers should begin within 24 to 72 hours as a result of maintenance
and management actions; however, total restoration of service would
take significantly longer.
While numerous agencies have the capability for emergency
communication within themselves, non-telephonic communication
among entities and agencies in the affected area is minimal. This is true
for Federal, State, and local agencies. This weakness has been pointed
out repeatedly by