An Assessment of the Consequences and Preparations for a Catastrophic California Earthquake: Findin | Page 9

quantitative
estimates of peak ground motion at various distances from the
postulated earthquakes were developed for use in the effects of severe
ground shaking on individual structures or critical facilities. No
estimates were made of localized effects, such as ground failures
related to liquefaction (the complete failure or loss of strength, of a
saturated soil due to shaking), landslides, and fault rupture. These
effects can be far more destructive than ground shaking alone.

[Illustration: Figure 1. Geographic Locations of Selected Regional
Events]
CHAPTER III
ASSESSMENT OF LOSSES FOR SELECTED POTENTIAL
CALIFORNIA EARTHQUAKES
A. INTRODUCTION
As part of a program that FEMA and its predecessor agencies have had
underway for a number of years, property loss and casualty estimates
were prepared in 1972 and 1973 for a number of potential maximum
credible earthquakes that could impact on the San Francisco and the
Los Angeles areas--North San Andreas (Richter magnitude 8.3),
Hayward (Richter magnitude 7.4), South San Andreas (Richter
magnitude 8.3), and Newport-Inglewood (Richter magnitude 7.5).
These estimates have now been updated as part of the current
assessment.
Estimates of property loss and casualties are based on the expected type
and distribution of damage for each postulated earthquake as
determined by the size and location of the earthquake and the
distribution and character of the buildings and structures within the
affected area. Methodologies for estimates of this type are approximate
at best. Consequently, the figures shown below may vary upward or
downward by as much as a factor of two or three. This degree of
uncertainty does not affect the validity of the conclusions of this report,
however, since there are greater uncertainties in all other aspects of
emergency response planning.
B. PROPERTY LOSS ESTIMATES
The property loss estimates were obtained by first estimating the total
replacement dollar value of buildings and their contents, multiplying
them by percentage loss factors (inferred from the anticipated strength
of shaking in each county), and then summing to obtain the aggregate
loss. Included in the estimates are private as well as Federal, State, and

local government buildings, insured and uninsured. Excluded from
consideration is the replacement value of transportation and
communication facilities, dams, utility installations, and special
purpose structures (e.g., convention centers and sports arenas). Also
excluded is the potential damage resulting from a major dam failure or
the indirect dollar losses due to such factors as higher unemployment,
lower tax revenue, reduced productivity, and stoppage of industrial
production. Experience indicates that indirect losses could be
approximately equal to the dollar amounts lost in buildings and their
contents. The property loss estimates for four postulated earthquakes on
the faults listed below are as follows.
TABLE 2
ESTIMATES OF PROPERTY LOSSES FOR REPRESENTATIVE
EARTHQUAKES[1]
-------------------------------------------------------------------------- Loss to
Loss of Building Contents Total Loss Fault ($ in Billions) ($ in Billions)
($ in Billions)
-------------------------------------------------------------------------- Northern
San Andreas 25 13 38 Hayward 29 15 44 Newport-Inglewood 45 24 69
Southern San Andreas 11 6 17 ---------- [1] Uncertain by a possible
factor of two to three.
--------------------------------------------------------------------------
C. CASUALTY ESTIMATES
Deaths and injuries in these earthquakes principally would occur from
failures of man-made structures, particularly older, multistory, and
unreinforced brick masonry buildings built before the institution of
earthquake-resistant building codes. Experience has shown that some
modern multistory buildings--constructed as recently as the late 1960's,
but not adequately designed or constructed to meet the current
understanding of requirements for seismic resistance--are also subject
to failure. Consequently, the number of fatalities will be strongly
influenced by the number of persons within high-occupancy buildings,
capable of collapsing, or by failure of other critical facilities such as

dams. Additional imponderables are the degree of saturation of the
ground at the time of the event and the possibility of weather conditions
conducive to the spread of fire. A conflagration such as occurred in the
1906 San Francisco earthquake, is not considered likely to occur in any
of the analyzed events, however, because of improvements in fire
resistance of construction and firefighting techniques. Nonetheless,
numerous smaller fires must be anticipated in any of the analyzed
events and a "Santa Ana type" wind could cause serious problems.
An additional element of uncertainty in estimating casualties from
earthquake stems from not knowing where most of the population will
be at the time of the earthquake. In the early morning (i.e., 2:30 a.m.)
most people are at home, by far the safest environment during a seismic
emergency. At 2:00 in the afternoon, on the other hand, the majority of
people are at their places of employment and therefore vulnerable to
collapse of office buildings. Around 4:30 p.m. many more people are in
the streets and thus subject to injury due to falling debris or failures of
transportation systems. Consequently, depending on the time of day,
wide variations in the number of casualties can be expected.
Following are estimates of dead