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 and injured (requiring hospitalization) for each of the four representative faults and for the three time periods just discussed.
TABLE 3
ESTIMATES OF CASUALTIES[1]
Fault Time Dead Hospitalized[2] ------------------------------------------------------------------- Northern San Andreas 2:30 a.m. 3,000 12,000 2:00 p.m. 10,000 37,000 4:30 p.m. 11,000 44,000
Hayward 2:30 a.m. 3,000 13,000 2:00 p.m. 8,000 30,000 4:30 p.m. 7,000 27,000
Southern San Andreas 2:30 a.m. 3,000 12,000 2:00 p.m. 12,000 50,000 4:30 p.m. 14,000 55,000
Newport-Inglewood 2:30 a.m. 4,000 18,000 2:00 p.m. 21,000 83,000 4:30 p.m. 23,000 91,000 ---------- [1] Uncertain by a possible factor of two to three.
[2] Injuries not requiring hospitalization are estimated to be from 15 to 30 times the number of deaths. -------------------------------------------------------------------
D. OVERVIEW OF OTHER TYPES OF DAMAGE
For this assessment, estimates of damage to substantial numbers of different type facilities essential to the immediate response capability were updated. Earthquakes associated with the same four major fault systems identified earlier in this chapter were used as a basis for these estimates. The types of facilities analyzed included _hospitals_, _medical supply storages_, _blood banks_, and _custodial care homes_, together with their essential services and personnel resources. Although newer hospitals in California are being built according to substantially improved seismic safety standards and practices, older hospital facilities can be expected to be poorly resistant to earthquakes.
Among residential buildings, single family homes are expected to suffer structural damage and loss of contents. Damage to multifamily dwellings--particularly older buildings--would, in all likelihood, be more extensive. Analysis of expected damage indicates that temporary housing for as many as 200,000 families might be needed--a requirement calling for careful planning and exceptional management skills.
Schools are judged to be among the safest facilities exposed to the earthquakes. Since passage of the Field Act in 1933, after the Long Beach earthquake, school buildings in California have been continuously improved to withstand seismic hazards.
As a result of continuing and substantial upgrading of design and construction practices in the past 10 years, dams and reservoirs can be expected to show an improved performance in an earthquake. Nonetheless, on a contingency basis, one dam failure might be assumed for each planning effort.
Realizing the fact that 84 key communications facilities, earth stations, Department of Defense voice and data switches, commercial transoceanic cable heads, Federal Telecommunications System switches, and major direct distance dial switches are located within 55 miles of either Los Angeles or San Francisco, damage must be expected to occur. With this realization, priorities have been assigned to all critical circuits transiting the key facilities, based on established criteria of criticality of service continuity. _National warning systems circuitry, command and control circuits, and circuits supporting diplomatic negotiations_ (of which a high concentration exists in California) are examples of those circuits carrying high-restoration priority.
In the civil sector there would be 24 to 72 hours of minimal communications, with a possible blackout of telephonic communications in the area immediately following an earthquake. The commercial carriers would institute network control procedures to regain control of the situation as fast as possible.
The impact on transportation facilities in any of the four hypothesized earthquakes could be massive. Since the magnitude and severity is unprecedented in recent years, conclusions regarding losses must be accepted as tentative. As in the case of hospitals, however, the lessons learned in earthquakes during the past 10 years are being incorporated in the design and construction of new facilities.
In general, all major transportation modes would be affected--_highways_, _streets_, _overpasses and bridges_, _mass transit systems_, _railroads_, _airports_, _pipelines_, and _ocean terminals_, although major variances in losses are expected among the modes. From a purely structural standpoint, the more rigid or elevated systems (such as railroads and pipelines) which cross major faults on an east-west axis would incur the heaviest damage, with initial losses approaching 100 percent. Other major systems (such as highways, airports, and pile-supported piers at water terminals) have better survivability characteristics and therefore would fare much better, with damage generally in the moderate range of 15 to 30 percent. These transportation facility loss estimates are stated in terms of immediate post-quake effects. They do not reflect the impact of priority emergency recovery efforts and expedient alternatives that are available, some within hours, to aid in restoration of transportation capacity. In addition, transportation systems generally have an inherently significant degree of redundancy and flexibility. Consequently, an unquantified but significant movement capability in all transport modes is expected to survive. Finally, these loss estimates do not take into account the question of availability of essential supporting resources, particularly petroleum fuels, electricity, and communications. In the initial response phase, these could prove to be the most limiting factors in the capability of the transportation system.
Business and industry would be affected by damage to office buildings, plants, and other support facilities. Although the 1971 San Fernando earthquake occurred on the margin of a largely suburban area, industrial facilities incurred significant damage. For example, several buildings of the kind commonly used for light industry or warehouses suffered from collapsed roofs or walls. Generally, building codes do not apply to special industrial facilities, and the ability of these structures to resist earthquake shaking will depend largely on the foresight of the design engineer. For example, a major electrical power switching yard and a water filtration plant were seriously damaged in the 1971 San Fernando earthquake.
About 10 percent of the population and industrial resources of the Nation are located in California. Over 85 percent of these resources (or about 8.5 percent of the Nation's total) are located in the 21 California counties that are subject to the possibility of damage from a major earthquake. Much of the aerospace and electronics industry is centered in California. For example, about 56 percent of the guided missiles and space vehicles, 40 percent of the semiconductors, 25 percent of the electronic computer equipment, and approximately 21 percent of the optical instruments and lenses manufactured in the Nation are manufactured in these 21 counties. The probability that all these counties would be affected by one earthquake is extremely remote; yet the significant concentration of key industries remains a concern. For example, about 25 percent of the Nation's semiconductors are manufactured in Santa Clara County, an area along the Northern San Andres fault that suffered very heavy damage in the 1906 San Francisco earthquake. Estimates of damage to these industrial facilities and the resulting loss of production have not been made. Similarly, the resulting impact of possible damage to national production has not been adequately analyzed.
Federally regulated financial institutions were generically analyzed to determine their ability to continue to promote essential services in the event of a major earthquake like those that have been postulated for this assessment. The conclusion reached thus far is that large-magnitude earthquakes pose no significant or unanticipated problems of solvency and liquidity for such institutions. The Federal Reserve System and other regulatory entities have procedures in place that are designed--and have been tested--specifically to provide for the continued operation of financial institutions immediately following an earthquake or other emergency.